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Hypothesis Based Testing (HBT) Cookbook


A cookbook on Hypothesis Based Testing, a personal scientific test methodology. Presented by STAG Software.

A cookbook on Hypothesis Based Testing, a personal scientific test methodology. Presented by STAG Software.

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  • 1. © 2011-12, STAG Software Private Limited. All rights reserved.STEM is the trademark of STAG Software Private Limited.HBT is the intellectual property of STAG Software Private Limited.This e-book is presented by STAG Software Private Limited www.stagsoftware.com 2
  • 2. Hypothesis Based Testing (HBT) is a scientific personal test methodology that is unique in its approach to ensuring cleanliness of software. It is agoal focused approach, commencing with setting up of cleanliness criteria, hypothesising potential defect types that can impede this, and thenperforming activities to ensure that testing is purposeful and therefore effective and efficient. The central theme HBT is constructing a hypothesesof potential defects that may be probable, and then scientifically proving that they do not indeed exist. The activities of testing like test strategy,test design, tooling & automating become purposeful as these are focused on uncovering the hypothesised defect types ensuring that theseactivities are done scientifically and in a disciplined manner.HBT is based on sound engineering principles geared to deliver the promise of guaranteeing cleanliness. Its core value proposition is abouthypothesising potential defects that may be present in the software and then allow you to engineer a staged detection model to uncover thedefects faster and cheaper that other typical test methodologies.HBT fits into any development methodology and weaves into your organisational test process. HBT is powered by STEMTM (STAG TestEngineering Method) a collection of EIGHT disciplines of thinking. STEM provides the foundation for scientific thinking to perform the variousactivities. It is personal scientific inquiry process that is assisted by techniques, principles and guidelines to decompose the problem, identifycleanliness criteria, hypothesise potential defect types, formulate test strategy, design test cases, identify metrics and build appropriate automation. 3
  • 3. Inspirations from natureHBT has been inspired by certain ideas and these are discussed below. The inspirations have come from “Properties of matter”, “Fractionaldistillation”, “Sherlock Holmes”, “Picture of baby growth”.Properties of matter Physical & Chemical properties of matter allow us to: ... classify “affected by” ... understand behaviours, interactions ... enable checking purity How can we use a similar train of thought to identify “properties of cleanliness” and then “types of defects”? “Properties of the system” End user expectations Cleanliness criteria Issues in specifications, structure, environment Potential Defect Types (PDT) and behaviour 4
  • 4. Inspirations from natureFractional distillation This is a technique to separate mixtures that have components of different boiling points In software systems, there exists a variety of defect types that may be present in the system. How can we apply this thought process to optimally uncover the defects, by “fractionally distilling” them? Can we separate these types of defects on the basis of certain properties and optimally uncover the defects?From : http://withfriendship.com 5
  • 5. Inspirations from naturePicture of baby growth The picture shows the health of the foetus/baby . This picture shows size, shape, parts and types of issues not present Seeking inspiration, can we depict the health of software system in a similar manner? Can we measure the ‘intrinsic quality’ at a stage? As we progressively evaluate in a staged manner, certain types of defects detected & removed and therefore quality grows. Can we chart this as “cleanliness index”?Source :http://www.environment.ucla.edu/media/images/Fetal_dev5.jpg 6
  • 6. Inspirations Sherlock Holmes Sherlock Holmes was person who applied deductive logic to solve mysteries. How can we see inspirations from Holmes to hypothesise the types of defects that may be present and prove presence of these? 7
  • 7. HBT - A Personal Scientific Test MethodologyTest methodologies focus on activities that are driven by a process which are powered by tools, yet successful outcomes stilldepend a lot on experience.Typically methodologies are at organisational level.On the other hand HBT is a personal scientific methodology enabled by STEMTM , a defect detection technology to deliver“Clean Software” 8
  • 8. Scientific approach to detecting defectsCleanliness criteria What is the end user expectation of “Good Quality”?Potential Defect Types What types of issues can result in poor quality?Evaluation Stage When should I uncover them?Test Types How do I uncover them?Test Techniques What techniques to generate test cases?Scenarios/Cases What are the test cases? Are they enough?Scripts How do I execute them?Metrics & Management How good is it? How am I doing? 9
  • 9. How is HBT different from other test methodologies?The typical test methodologies in vogue have relied on strength of the process and the capability of the individual to ensurehigh quality in the given cost and time constraints. They lack the scientific rigour to enable full cost optimisation and moreoften rely on automation as the means to driving down cost and cycle time. For example, they do not provide a strong basisfor assessing the quality of test cases in terms of their defect finding potential and therefore improve effectiveness andefficiency.HBT on the other hand enables you to set a clear goal for cleanliness, derive potential types of defect and then devise a“good net” to ensure that these are caught as soon as they get injected. It is intensely goal-oriented and provides you with aclear set of milestones allowing you to manage the process quickly and effectively. Goal drives la T ic B yp H Activities T Activities defect detection ...................................... ...................................... Powered by Powered by technology experience (STEM) ...................................... ...................................... ...................................... ...................................... ...................................... ...................................... ...................................... ...................................... ...................................... ...................................... hopefully results in Goal 10
  • 10. Hypothesis Based Testing - HBT 2.0A Quick Introduction Personal, scientific test methodology. SIX stage methodology powered by EIGHT disciplines of thinking (STEMTM). Setup Hypothesise Cleanliness Criteria Potential Defect Types SUT Nine Stage Cleanliness Assessment Defect Removal Filter 11
  • 11. A quick introduction to HBT SIX stages of DOING powered EIGHT disciplines of THINKING by D8 D1 S6 S1 Analysis & Business value Assess & Understand management understanding ANALYSE EXPECTATIONS D7 D2 Execution & Defect D8 D1 reporting STEM Core hypothesis Tooling D7 D2 S5 STEM Understand 32 core SUPPORT S2 D6 D3 CONTEXT concepts D5 D4 Strategy & Visibility planning D3 D6 Devise Formulate HYPOTHESIS Tooling Test design PROOF S4 S3 D5 D4 HBT powered STEM Personal test methodology by Defect detection technology 12
  • 12. D1 Business value understanding D2 Defect hypothesis D3 Test strategy & planning Landscaping Orthogonality principle Viewpoints EFF model Tooling needs assessment Reductionist principle Defect centricity principle Defect centred AB Interaction matrix Negative thinking Quality growth principle Operational profiling Orthogonality principle Techniques landscape Attribute analysis Defect typing Process landscape GQMD4 Test design D5 Tooling Reductionist principle Input granularity principle Automation complexity Box model assessment Behaviour-Stimuli approach 32 core Minimal babysitting principle Techniques landscape concepts Separation of concerns Complexity assessment Tooling needs analysis Operational profiling Test coverage evaluation Visibility Execution & Reporting Analysis & ManagementD6 D7 D8 GQM Contextual awareness Gating principle Quality quantification model Defect rating principle Cycle scoping 13
  • 13. Connecting HBT Stages to theScientific approach to detecting defects S1 Cleanliness criteria Potential defect types S3 S2 Expectations Staged & purposeful detection S4 Complete test cases S6 Goal directed measures Sensible automation S5 14
  • 14. Clear baseline Set a clear goal for quality Cleanliness criteria Potential defect types Example: Clean Water implies S1, S2 1.Colourless Staged & purposeful 2.No suspended particles 3.No bacteria detection 4.Odourless Expectations What information(properties) can be used to identify this? Complete test cases ... Marketplace,Customers, End users ... Requirement(flows), Usage, Deployment ... Features, Attributes Goal directed ... Stage of development, Interactions Sensible automation measures ... Environment, Architecture ... Behaviour, Structure 15
  • 15. A goal focused approach to cleanliness Identify potential defect types that can impede cleanliness Cleanliness criteria Potential defect types S3 Example: Data validation Timeouts Staged & purposeful Resource leakage detection Calculation Expectations Storage Presentation Complete test cases Transactional ... Scientific approach to hypothesising defects is about looking at Goal directed FIVE Aspects - Data, Logic, Structure, Environment & Usage Sensible automation measures from THREE Views - Error injection, Fault proneness & Failure Use STEM core concepts > Negative thinking (Aspect) > EFF Model (View) “A Holmes-ian way of looking at properties of elements” 16
  • 16. Levels, Types & Techniques - STRATEGY NINE levels to Cleanliness Cleanliness criteria Potential defect types L9 End user value S4 Staged & purposeful L8 Clean Deployment detection Expectations L7 Attributes met Complete test cases L6 Environment cleanliness L5 Flow correctness Goal directed Sensible automation measures L4 Behaviour correctness L3 Structural integrity L3Quality Levels Test Techniques (T1-T4) PDT7 L2 Input interface cleanliness TT5 PDT6 TT4 TT3 T3 L2 PDT5 L1 Input cleanliness PDT4 TT3 TT2 L1 PDT3 T2 PDT2 TT2 TT1 T1 PDT1 TT1PDT: Potential Defect Types 17
  • 17. Countable test cases & Fault coverageCountable test cases & Fault coverage Use STEM Core concepts Cleanliness criteria Potential defect types > Box model > Behaviour Stimuli approach > Techniques landscape > Coverage evaluation Staged & purposeful detection to Expectations - Model behaviour S4 - Create behaviour scenarios Complete test cases - Create stimuli (test cases) Irrespective of who designs, #scenarios/cases shall be same - COUNTABLE Goal directed Sensible automation Test Scenarios/Cases measures R1 PDT1 TS TC1,2,3 R2 PDT2 TT R3 TS TC4,5,6,7 PDT3 Requirements & Fault traceability That test cases for a given requirement shall have the ability to detect specific types of defects FAULT COVERAGE 18
  • 18. Focused scenarios + Good Automation Architecture Level based test scenarios yield shorter scripts that are more flexible for change and easily maintainable. Cleanliness criteria Potential defect types L9 End user value Staged & purposeful detection L8 Clean Deployment Expectations L7 Attributes met Complete test cases L6 Environment cleanliness S5 L5 Flow correctness Goal directed Sensible automation measures L4 Behaviour correctness L3 Structural integrity L2 Input interface cleanliness L1 Input cleanliness 19
  • 19. “Cleanliness Index” - Improved visibility L4 Cleanliness criteria Potential defect types PDT10 TT8 PDT9 TT7 Staged & purposeful L3 PDT9 TT6 Cleanliness detection PDT8 TT5 Expectations PDT7 TT4 Complete test cases L2 PDT6 PDT5 TT3 L1 PDT4S6 Goal directed PDT3 Sensible automation measures PDT2 TT2 PDT1 TT1 Quality report Stage CC1 CC2 CC3 CC4 R1 Met R2 Not met R3 “Growth of a baby” Partially met R4 R5 20
  • 20. HBT StagesSix stages to produce clean software 21
  • 21. Six staged methodology to produce clean softwareThe act of validation in HBT consists of “SIX Stages of DOING”. It commences with first two stages focused on a scientific approach tounderstanding of the customer expectations and the the context of the software. One of the key outcomes of the first two stages is“Cleanliness Criteria” that gives a clear understanding of the expectation of quality. In the third stage, the Cleanliness Criteria and theinformation acquired in the first two stages are used to hypothesise potential types of defects that are probable in the software. The fourthstage consists of devising a proof to scientifically ensure that the hypothesised defects can be indeed be detected cost-efficiently. The fifthstage focuses on building the tooling support needed to execute the proof. The last stage is about executing the proof and assessing if thesoftware does indeed meet the Cleanliness Criteria. Who are the customers, end users, what do they need, and S1 S6 S1 what do they expect? Assess & Understand ANALYSE What are the features of the system, what technologies are EXPECTATIONS S2 used, architecture? D8 D1 What types of defects may be present? D2 S3 Tooling D7 Understand What types of fishes to catch? S5 STEM SUPPORT S2 D3 CONTEXT D6 D5 D4 What is strategy, plan, test scenarios/cases? S4 Sherlock Holmes Devise Formulate PROOF HYPOTHESIS What tools do I need to detect the defects? S5 Boat in the fishing analogy S4 S3 How am I doing? How is quality? S6 Fisherman 22
  • 22. Stage #1 : Understand EXPECTATIONS The perception that end-users have of how well the product delivers the needs denotes the quality of the Understand the software/system. "Needs" represent the various features that the software/system needs to have, to allow the marketplace for end-user to fulfill his tasks effectively and efficiently. "Expectations" on the other hand represent how well the the system needs are fulfilled. The final software/system may be deployed in different marketplaces addressing the needs of various types of Understand the customers. Hence it is imperative that we understand the various target markets (i.e marketplace) where the technology(ies) used software or system will be deployed. There could be different types of customers in the marketplace. Hence it is necessary to identify the various types of customers and then finally identify various types of end-users present in the customer. What we have done now is to start from outward direction i.e marketplace and adopt a customer/end-user centric view to understand the needs and expectations.Understand deployment environment Once we have identified the various types of customers and the corresponding end-users, we can move on to understand the various technologies that make up the software or the system and also a deployment environment. The intent is to get a good appreciation of the "construction components" and the target environment of deployment. It is imperative that we should have a good understanding of the internal aspectsIdentify end user types and not merely the external aspects of the system.& #users for each type Now were ready to go into a detailed analysis of the various types of end-users and the typical number of users for each of these end-users. Subsequent to this, we need to identify the various business requirements Identify business i.e. "needs" for each end-user.requirements for each user type At the end of the stage, the objective is to have a good understanding of the various end-users and their needs paving the way to understanding expectations clearly. 23
  • 23. Needs & Expectations NEEDS Customers in End users Should write Should have a eraser Kids Education EXPECTATIONS Should be attractive Seniors Should be non-toxic Lead should not break easily Product Artists Drawing e.g Pencil NEEDS Draftsmen Should write Should not need sharpening Management EXPECTATIONS Corporate Thickness should be consistent Variety of thickness should be Engineering available Variety of hardness should be Admin availableNeeds typically features that allow to get the job done.Expectations are how well the need is satisfied.Remember Functional & Non-functional requirements ? 24
  • 24. What does “understanding” involve?Good understanding of what is expected is key to effective testing. To accomplish this, it is imperative that we commence from understandingwho the various types of end users, their requirements and subsequently the expectations that they have from these. Having a deep domainknowledge helps immensely. But what if I this is a domain that I am not very conversant with? Is there a scientific way to undertand?Understanding is a non-linear activity, it is about identifying the various elements and establishing connections between these. In the process ofconnecting the dots, missing information is identified, leading to intelligent questions. Seeking answers to these questions aids in deepening theunderstanding. These are some of the elements that need to be understood. Some of the information elements are “external to the system” i.e. marketplace, customer types, end users, business requirements while some are “internal to the system” i.e. features, architecture, technology etc. Stage #1 (Understand EXPECTATIONS) focuses on “external information while Stage #2 (Understand CONTEXT) focuses on “internal information”. “Good testing is about asking intelligent questions leading to deeper understanding.” 25
  • 25. Information extracted & artefacts generated Information At each stage, certain information is extracted, understood and transformed into artefacts useful to perform effective & efficient testing. Marketplace Customers Artefacts The key outcomes as demonstrated by the artefacts are: User types System overview ‣The big picture of the system ‣The various end users ascertained for Requirements different classes of customers in different HBT marketplaces Stage #1 User type list Deployment ‣A list of business requirements for each type of end user. environment. Requirement map Technology Lifecycle stage In Stage #1, the focus is on external information that relate to marketplace, #Users/type customers, end users andHBT Stage 1 business “Good understanding is key to effective requirements. This stage is useful to get the testing. Identifying who will use what is the bigger picture of the system and its potential beginning to become customer-focused” usage and the how it is deployed.
  • 26. Deliverables from Stage #1 Should contain a a good overview of the marketplace, the various types of customers, end-users types, System overview deployment environment and technologies that will be used to build the system. Should contain a list of the various types of users for different types of customers in various market User type list segments. Should contain a list of the business requirements and high level technical features mapped to the various Requirement map individual types.STEM Discipline applied in Stage #1 The STEM discipline “Business value understanding” of STEM is applied in this stage of HBT. The two STEM core concepts of “Landscaping” and “Viewpoints” are useful in this stage to scientifically understand the expectations. 27
  • 27. Stage #2 : Understand CONTEXT In this stage the objective is to understand the technical context in terms of the various features, their relative Identify technical business value, the profile of usage and ultimately arrive at the cleanliness criteria. Note that at this stage, we features and baseline are moving inward to get a better understanding of technical features of the system. them Having identified the various business requirements mapped by each type of end-user, the next logical step is to drill-down to the various technical features for each business requirement. It is important to understand Understand the various technical features that constitute the entire system do not really work in isolation. Therefore it is dependencies necessary to understand the interplay of the features i.e. understand the dependencies of a feature with other features. Understanding this dependency is very useful at later stages of the life cycle, particularly to regress Understand profile of optimally. usage We now have a list of requirements and the corresponding technical features mapped by each end-user. We are ready to proceed logically to understand the profile of usage of each of the features by the various end-Identify critical success users. To do this it is important to understand the typical in the maximum number of users for each user type factors and then the volume of usage by each user for every technical feature. Since we already have a mapping between the end-user type and the technical feature feature, all we have to do is to understand as to approximately how many times this feature will be used by typical end-user of that end user type. The intentPrioritize value of end of this is to gain a deeper understanding of the usage profile to enable an effective strategy formulation at theusers(s) and features later stage of HBT. It is not only sufficient that the features work correctly, it is equally important that the various attributes of Ensure attributes are the nonfunctional aspects of the various features are indeed met. Typically nonfunctional aspects of the testable system are identified in the highest system level, and typically turn out to be fuzzy. Good testing demands that each requirement is indeed testable. In HBT, attributes are identified for each key feature and then aggregated to form the complete set of nonfunctional requirements. We will do this in two stages: firstly identifying the Setup cleanliness critical success factors for the technical features and thereof the business requirement and then detailing the criteria critical success factors to arrive at the nonfunctional requirements or attributes. Hence after figuring out the usage profile, identify the success factors for each business requirement. 28
  • 28. Stage #2 : Understand CONTEXTGood testing is not about testing all features equally, it is about learning to focus more on those requirements/features that affect the customerexperience significantly. This does not imply that some requirements/features are less important than the others, it simply means that somerequirements/features are more important . Before we start detailing the various attributes, it is worthwhile to the prioritize the variousrequirements /features and also various end-user types. To prioritize, start by prioritizing the various types of end users in terms of theirimportance to the successful deployment of the final system. Subsequently rank the importance of each of the requirement/feature for each ofthe end-user type. At the end of this exercise, we should have a very clear understanding of the business value of each requirement/feature. Notethat the understanding of usage profile comes in very handy here.Now we are ready to derive the various attributes from the previously identified success factors and ensure that they are testable. A testablerequirement simply means that it is an unambiguously possible to state whether it failed all passed after executing it. In the context of attributes,testability implies that each attribute does indeed have a clear measure/metric. Therefore it is necessary to identify the measures and theexpected value of the measures for each of the attribute.Having identified the various technical features and the corresponding attributes, the usage profile in the ranking of the requirements/features,we are now set to identify the various criteria that constitute the cleanliness of the intended software. Cleanliness criteria in HBT representstestable expectations. Cleanliness criteria provides a very strong basis for ensuring a goal-focused testing. This allows one to identify potentialtypes of defects and then formulate an effective strategy in the complete set of test cases It is important that the cleanliness criteria is not vagueor fuzzy. 29
  • 29. Information extracted & artefacts generated At each stage, certain information is extracted, Artefacts understood and transformed into artefacts useful to perform effective & efficient testing. Information Feature list The key outcomes as demonstrated by the Features artefacts are: Value prioritization ‣A clear list of technical features matrix ‣Ranking of features to focus on high risk Usage areas ‣Profile of usage HBT Usage profile ‣List of attributes Focus areas Stage #2 ‣Feature interactions Attributes list ‣Clarity of expectations outlined as Attributes “Cleanliness criteria” Interaction matrix Interactions Cleanliness criteria In Stage #2, the focus is on internal information that relate to technical features, their interactions, focus areas, attributes, architecture, technology. 30
  • 30. Deliverables from Stage #2 Feature list Should contain the list of technical features, that forms the technical features baseline. Value prioritization Should contain a set of users, requirements and features ranked by importance. matrix Usage profile Should contain a the profile of various operations by various end users over time. Should contain the key attributes stated objectively i.e. state expected value for all the measures Attributes list for each attribute. Should contain the which feature affects what. Note that this should list the interactions and not the details Interaction matrix of interactions. The objective is to get a rapid understanding of the linkages. Cleanliness criteria Should contain criteria that need to be met to ensure that the deployed system is indeed clean.STEM Discipline applied in Stage #2 The STEM discipline “Business value understanding” of STEM is applied in this stage of HBT. The STEM core concepts of “Interaction matrix”, “Operational profiling”, “Attribute analysis” and “GQM” are useful in this stage to scientifically understand the context. 31
  • 31. Cleanliness criteriaCleanliness criteria is a mirror of expectations, The intention is to come up with criteria that if met will ensure that system meets theexpectations of the the various end users. This is not be confused with “Acceptance criteria”, as “Acceptance criteria” is typically at a higherlevel. Acceptance criteria is typically “extrinsic” in nature i.e. it describes aspects like long duration running, migration of existing data, cleaninstallation and running in the final deployment environment, delivering stated performance under real-life load conditions.Cleanliness criteria represents the “intrinsic quality” i.e. what properties should the final system have to ensure that it is deemed clean?Use the properties of the FIVE aspects of Data, Business logic, Structure, Environment, Usage as applied to your application to arrive at thesecriteria specific to your application.Note that the cleanliness criteria should both the the functional and non-functional requirements. The recommended style of writing Cleanliness criteria is: “That the system shall meet ....” Examples: That the system is able to handle large data (need to qualify large) That the system releases resources after use. That the system displays meaningful progress for long duration activities. That the system is able to detect inappropriate environment/configuration. 32
  • 32. Stage #3 : Formulate HYPOTHESIS Having understood the expectations and the context resulting in the formulation of cleanliness criteria, we are ready to hypothesize the potential defects that could affect the cleanliness criteria. This is one of the important stages of HBT resulting in a clear articulation of the various types of defects and forms the basis for the remaining stages of HBT. The key idea is to use the external information like the feature’s behaviour, environment, attributes, usage and internal information like construction material i.e technology, architecture to hypothesize the potential defects that may be present in the software under construction. Also note that the history of the previous versions of the software or similar systems can also be used to construct and strengthen the hypothesis. Having hypothesized the potential defects, it is possible to scientifically construct a validation strategy and design adequate test cases, thereby ensuring that the final system to be deployed is indeed clean. The FIVE key aspects useful for constructing hypotheses of defects are: data, business logic, structure, environment and usage. This HBT stage allows us to follow a structured &scientific approach to the hypothesize the potential effects ensuring that we do not miss any. 33
  • 33. Stage #3 : Formulate HYPOTHESIS (continued) Firstly use the external information like data specification and business logic Identify potential faults for the five specification to identify the potential defects. The information related to data that could aspects - Data, Business logic, Structure, help are: data type, boundaries, volumes, rate, format, data interrelationships. The intent Environment, Usage should be to get into a "negative mentality" and think of what can go wrong with respect to all the information related to the data and then produce a list of potential Identify potential failures of the five defects. aspects - Data, Business logic, Structure, Environment, Usage Now use the information related to the business logic to identify the potential effects. Business logic or the intended behaviour primarily transforms the various inputs i.e. input data to outputs that the user values. The intention is to identify potential Identify potential errors that could be transformation losses. The information specific to business logic that is useful for injected in the five aspects - Data, arriving at potential defects are : the various conditions and their linkages, values of Business logic, Structure, Environment, conditions, exception handling conditions, access control and dependencies on the Usage other parts of the software. Once again, the intent is to get into a "negative mentality", and identify erroneous business flows of logic. Now identify potential defects (PD) & Up to now the focus has been on using external information like the specification of combine PDs, remove duplicate PDs data and business logic to identify the potential defects. Now focus on the internal information like structure of the system and construction materials(i.e. language, technology) used to build the system to hypothesize potential defects. Structure at the Group similar PD to form Potential highest level represents the deployment architecture while structure at the lowest level Defect Types (PDT) represents the structure of the code. Some of the structural information that could be useful to hypothesize are: flow of control, resource usage, distributed architecture, interfacing techniques, exception handling, timing information, threading, layering. As Map PDTs to the elements-under-test i.e.features/requirements explained above, continue with the similar train of thought of examining these information with intent to identify potential problems in the structure. 34
  • 34. Stage #3 : Formulate HYPOTHESIS (continued)Having identified potential defects using the behavioural and structural information, examine information related to environment and how theycan affect the deployed system. By environment, we mean the associated hardware and software on which the system is deployed and thehardware, software and application resources used by the system. The objective is to examine carefully how these can affect the finally deployedsystem. Some of the key information related to the environment that could be useful are: hardware/software versions, system access control,application configuration information, speed of hardware (CPU, memory, hard disk, communication links), environment configuration information(e.g. #handles, cache size etc), system resources (hardware, OS and other applications).Up till now we have taken a fault-centric approach of looking for potential faults (aka defects) by examining external or internal information. Inaddition to a fault-centric approach, we can also view the system from potential failure points and then identify the potential defects.Additionally, it is also possible to examine the system from an error injection point of view. That is, understand the kinds of potential errors thatcould be injected into the system to irritate the potential defects if any. The objective is to ensure that we have examined the system from allthree views (error centric, fault centric & failure centric) and thereby ensure that we have not missed any potential defects.A failure centric approach demands that we wear an end-user hat and identify the potential failures that could cause business loss. The cleanlinesscriteria formulated earlier could come in very handy as this would force us to think like a customer/end-user. What we trying to do is to ensurethat we have considered all the potential failures and therefore hypothesized the potential defects.Now move to a user centric view to examine the various ways that an end-user could abuse the system by identifying the various ways errorscould be injected into the system. Not that an end user does not always connote a physical person, it could be another system that interacts withthe system via some interface. so examine the various points of interaction and look at the possibilities of their injection and then hypothesize thepotential defects that could get irritated by these errors. The kinds of information that could be useful here are: workflows, data access, interestingways of using the system, accessibility, environmental constraints faced by the physical end-user and potential deviant ways of using the system.Then consolidate the potential defects and group similar ones into potential defect types (PDT). Finally map the PDTs to the various elements-under-test i.e. feature/requirements. Now we have a clear notion as to what types of defects that we should look forward to uncovering in whatparts of the system. 35
  • 35. Information extracted & artefacts generated At each stage, certain information is extracted, understood and transformed into artefacts useful to perform effective & efficient testing. Information Data Structure Artefacts The key outcomes as demonstrated by the Environment artefacts are: HBT PD catalog Stage #3 ‣List of potential defect types Business logic ‣Mapping between PDTs & the elements- Fault traceability under-test i.e. Feature/Requirement matrix Usage Attributes Past defects In Stage #2, the focus is on hypothesizing PDTs using the FIVE aspects of Data, Business logic, Structure, Environment & Usage from THREE views - Error-centric, Fault-centric & Failure-centric. 36
  • 36. Deliverables from Stage #3 PD catalog Should contain the list of potential defects and the potential defect types Fault traceability Should contain the mapping between the potential defect types/potential defects and features/requirements. matrixSTEM Discipline applied in Stage #3 The STEM discipline “Defect hypothesis” of STEM is applied in this stage of HBT. The STEM core concepts of “Negative thinking”, “EFF model”, “Defect centricity principle” and “Orthogonality principle” are useful in this stage to scientifically hypothesize defects. 37
  • 37. Stage #4 : Devise PROOF (Part #1: Test Strategy & Planning)HBT being a goal focused test methodology, the intent is about figuring out an optimal approach to detect the potential of defects in thesystem. Therefore strategy in HBT is about staging the order of defect detection, identifying tests that are needed to uncover the specificdefect types and finally choosing test techniques best suited for each type of test.Typically we have always looked at the levels of testing like unit, integration and system from the aspect of the “size” of entity-under test. Unittest is typically understood as being done on the smallest component that can be independently tested. Integration test is typically understoodas being done once the various units have been integrated. System test is typically seen as the last stage of validation and is done on the wholesystem.What is not very necessarily very clear is the specific types of defects that are expected to be uncovered by each of these test levels. In HBT,the focus shifts to specific types of defects to be detected, and therefore the act of detection is staged to ensure an efficient detectionapproach.In HBT, the notion is of quality levels, where each quality level represents a milestone towards meeting the final cleanliness criteria. In otherwords each quality level represents a step in the staircase of quality. The notion is to ensure that the defects that can be caught earlier isindeed caught. So the first step to formulation of strategy is to stage the potential defects and thereby formulating the various quality levels.However in HBT, there are NINE pre-defined quality levels where the lowest quality level focuses on input correctness progressively goingonto the highest quality level to validate of the intended business value is indeed delivered. 38
  • 38. Stage #4 : Devise PROOF (Part #1: Test Strategy & Planning) Understand scope Having identified the various types of potential defect types to be detected at various levels, it is now necessary to understand the specific types of tests needed to uncover these potential defects. In HBT each test shall be intensely goal focused. This means that a type of test shall only uncover specific type of defects. Choose quality levels The act of test type identification results in specific types of tests to be done at each of the quality levels. Now that we know what types of defects need to be detected when and where what type of tests, we need Identify test types to know how to design sufficient yet adequate test cases for each type of test. In HBT, a test technique is one that allows us to design test cases. Based on the types of defects i.e. types of tests, we have to identify the test technique(s) that is best suited for uncovering these types of the defects. Identify test techniques Now we have a clearer idea of various types of defects, the levels of detection, types of tests and test techniques., we are now ready to identify the optimal detection process best suited for design/execution of Identify detection process test cases. The the act of identifying detection process also allows us to understand whether we need technology support to be able to execute test cases and therefore pave the way for automation strategy. Identify tooling needs At this point in time we have a strategy and are ready to develop the detailed test plan. Some of the key elements of the test plan is the estimation of effort and time and formulating the various test cycles. In HBT cycles are formulated first and then effort and time estimated. Formulate cycles Finally potential risks that could come in the way of executing the test plan are identified and the risk management plan put in place. Estimate effort In summary, a strategy in HBT is a clear articulation of the quality levels, test types test techniques and detection process model. Identify risks 39
  • 39. Information extracted & artefacts generated At each stage, certain information is extracted, understood and transformed into artefacts useful Information to perform effective & efficient testing. Cleanliness criteria PDT Artefacts Attributes The key outcomes as demonstrated by the HBT Test strategy artefacts are: Techniques Stage #4 ‣Test strategy ‣Test plan Deployment env. Test plan Scope of work #Scenarios Risks In Stage #4 (Part 1) the focus is on 1 HBT Stage identifying the quality levels, test types, test techniques and the detection process. 40
  • 40. Deliverables from Stage #4 (Part #1) Test strategy Should contain the quality levels, test types, test techniques & detection process Test plan Should contain the test effort estimate, cycle details and the potential risk & mitigation plan.STEM Discipline applied in Stage #4 (Part #1) The STEM discipline “Strategy & Planning” of STEM is applied in this stage of HBT. The STEM core concepts of “Orthogonality principle”, “Quality growth principle”, “Defect centered activity breakdown” , “Cycle scoping” are useful in this stage to scientifically developing the strategy & plan. 41
  • 41. Stage #4 : Devise PROOF (Part #2: Test Design) The act of designing test cases is a crucial activity in the test life cycle. Effective testing demands that the test cases possess the power to uncover the hypothesized potential defects. It is necessary that the test cases are adequate and also optimal. In HBT the design is done level-wise and within each level test-type wise. Based on the level & type, the test entity may be different. The test design activity for an entity for a type of test at a quality level consists of two major steps, firstly to design test scenarios and then generate these test cases for each scenario. Test scenarios are designed entity-wise and therefore there is a built-in notion of requirements traceability. In addition to requirements traceability, it is expected that the test scenarios and corresponding test cases are traced to the potential types of defects that they are expected to uncover. This is termed “Fault traceability”. 42
  • 42. Stage #4 : Devise PROOF (Part #2: Test Design) Identify test level to design The act of test design commences with the identification of the quality level and then the specific type consider & identify entities of test for which the test cases are to be designed. This allows us to identify the various test entities for which test cases have to be designed. Identify conditions & data Having identified the test entities it is then required to identify the conditions that govern the business logic and the data elements that drive these conditions. Subsequent to this, build the behavioral model. Use the behavioral model to generate test scenarios. Then for every scenario, identify the data thatModel the intended behaviour varies and then generate values for each data element. Finally combine the data values to generate thesemi-formally test cases. Since we have designed scenarios/cases entity-wise, requirements traceability is built-in i.e. the designedGenerate the test scenarios scenarios/cases automatically trace to the entity (or requirement). Now map the scenarios/cases to the hypothesized PDTs to build the fault traceability matrix.For each scenario, generate Finally assess the test adequacy of the designed scenarios/cases by checking test breadth, depth &test cases porosity.Trace scenarios to PDT &entity-under -testAssess the test adequacy byfault coverage analysis 43
  • 43. Information extracted & artefacts generated At each stage, certain information is extracted, understood and transformed into artefacts useful Information to perform effective & efficient testing. Conditions Artefacts Data Test scenarios & Logic cases The key outcomes as demonstrated by the HBT artefacts are: Stage #4 Requirements ‣Test scenarios & cases Structure ‣Requirements traceability matrix traceability matrix ‣Fault traceability matrix PDT Fault traceability matrix Defect escapes Attributes In Stage #4 (Part 2), the focus is on designing test scenarios/cases that can be proved to be adequate and have the power to uncover the hypothesized PDTs. 44
  • 44. Deliverables from Stage #4 (Part #2) Test scenarios & Should contain the test scenarios/cases for each entity for all types of tests at various quality levels cases Requirements Should contain the mapping between the scenarios/cases and the entity-under-test traceability matrix Fault traceability Should contain the mapping between the scenarios/cases and the PDTs matrixSTEM Discipline applied in Stage #4 (Part #2) The STEM discipline “Test design” of STEM is applied in this stage of HBT. The STEM core concepts of Reductionist principle, Input granularity principle, Box model , Behavior-Stimuli approach, Techniques landscape, Complexity assessment,Operational profiling, Test coverage evaluation are useful in design test scenarios/cases scientifically. 45
  • 45. Stage #4 : Devise PROOF (Part #3: Metrics Design) In this stage, the objective is to design measurements to manage the process of validation in an Identify progress aspects effective and efficient manner. Since HBT is a good focused test methodology, it is necessary to device measurements that enable us to clearly show the progress towards this goal. Identify adequacy(coverage) The measurements in HBT are categorized into progress related measures, test effectiveness aspects measures and system risk measures. Therefore it is necessary to identity the various aspects related to progress, effectiveness and the system health.Identify progress aspects Once the aspects are identified, key goals related to these are identified and then the metrics formulated. Finally it is necessary to understand when to measure and how to measure.For each of the aspects identifythe intended goal to meetFor each of these goals, identifyquestions to askTo answer these questions,identify metricsIdentify when you want tomeasure and how to measure 46
  • 46. Information extracted & artefacts generated At each stage, certain information is extracted, understood and transformed into artefacts useful to perform effective & efficient testing. Information Quality aspects Progress aspects Artefacts HBT The key outcomes as demonstrated by the Process aspects Stage #4 artefacts are: Metrics chart ‣Chart of metrics that are goal-focused Organization goals When & how to measure In Stage #4 (Part 3), the focus is on designing metrics that will ensure that we stay on course towards the goal. 47
  • 47. Deliverables from Stage #4 (Part #3) Metrics chart Should contain the list of metrics, collection frequency and a how this meets the goal.STEM Discipline applied in Stage #4 (Part #3) The STEM discipline “Visibility” of STEM is applied in this stage of HBT. The STEM core concepts of GQM, Quality quantification model are useful in design metrics that are goal-focused. 48
  • 48. Stage #5 : TOOLING support Perform tooling benefit In this stage, the objective is to analyze the support that we need from tooling/technology to analysis perform the tests. Automation does always imply scripting that is typically automating the designed scenarios. It could also involve development of test bench, custom tooling to enable the system to be tested. Identify automation scope This stage of HBT allows you to identify the tooling needs, understand issues/complexity involved, perform cost-benefit analysis, evaluate existing tools for suitability/fitment and finallyAssess automation complexity devising a good architecture that provides for flexibility/maintainability before embarking onto automation.Identify the order in whichscenarios need to be automatedEvaluate toolsDesign automation architectureDevelop scriptsDebug and baseline scripts 49
  • 49. Information extracted & artefacts generated At each stage, certain information is extracted, Information understood and transformed into artefacts useful Artifacts to perform effective & efficient testing. Automation Needs & benefits objectives document Scope Complexity assessment report The key outcomes as demonstrated by the Scenarios to artefacts are: automate Tooling requirements ‣The reason for tooling & automation HBT ‣Challenges involved Stage #5 ‣Requirements of tooling Scenario fitness ‣Scope of tooling & automation Automation scope ‣Architecture of automation Technologies used ‣Automated scripts Automation architecture Tool info. Tooling & Scripts Complexity info. In Stage #5, the focus is on identifying tooling requirements and building automated scripts that is delivers value & ROI. 50
  • 50. Deliverables from Stage #5 Needs & benefits Should contain the technical & business need for automation. document Complexity Should contain the technical challenges of automation assessment reportTooling requirements Should contain the requirements expected out of automation Automation scope Should contain scope of automation Automation Should contain the architecture adopted to building tooling/scripts architecture Tooling & Scripts The actual tools/scripts for performing automated testingSTEM Discipline applied in Stage #5 The STEM discipline “Tooling” of STEM is applied in this stage of HBT. The STEM core concepts of Automation complexity assessment, Minimal babysitting principle, Separation of concerns, Tooling needs analysis are useful in adopting a disciplined approach to tooling & automation and deliver the ROI.. 51
  • 51. Stage #6 : Assess & ANALYZE Identify test cases/scripts This stage is where you execute the test cases, record defects, report to the team and take to be executed appropriate action to ensure that the system/application is delivered on time with the requisite quality. Execute test cases, record outcomes Record defects Record learnings from the activity and the context Record status of execution Analyze execution progressQuantify quality and identify risk to delivery Update strategy, plan, scenarios, cases/scripts 52
  • 52. Information extracted & artefacts generated At each stage, certain information is extracted, Artifacts understood and transformed into artefacts useful to perform effective & efficient testing. Execution status report Information Defect report The key outcomes as demonstrated by the artefacts are: Execution ‣Report of test execution & progress Progress report ‣Defect report information HBT ‣Report on cleanliness aka quality Defect Stage #6 ‣Learnings from execution resulting in information Cleanliness report improved strategy, scenarios & cases ‣Any other key learnings Context Updated strategy, plan, scenarios & cases Key learnings In Stage #6, the focus is on ensuring a disciplined execution, intelligent analysis and continuous learning to ensure that the goal is reached. 53
  • 53. Deliverables from Stage #6 Execution status Should contain the status of test execution report Defect report Should contain defect information Progress report Should contain progress of execution and thereof the cycle Cleanliness report Should contain the cleanliness index and how well the cleanliness criteria has been met Updated strategy, Updated strategy, plan, scenarios, cases based on learnings from execution plan, scenarios & cases Key learnings Key observations/learnings that could be useful in the futureSTEM Discipline applied in Stage #6 The STEM disciplines of “Execution & reporting” and “Analysis and management” of STEM are applied in this stage of HBT. The STEM core concepts of Contextual awareness, Defect rating principle, Gating principle, Cycle scoping enable a disciplined execution, fosters continual learning and stay focused on the goal. 54
  • 54. STEM Disciplines 55
  • 55. Discipline #1 : Business value understandingHow to This discipline enables one to understand the system, create a baseline of features, attributes andUnderstand a system finally expectations. This discipline consists of SEVEN tools, each of which uses certain STEM core concepts to ensure these are done in a scientific and disciplined manner.Landscaping | Viewpoints Good quality implies meeting expectations. This requires that we understand expectations inHow to additions to the needs as delivered by the requirements. Understanding the intended businessCreate a functional baseline value to delivered is key to this.Viewpoints | Reductionist principleHow toCreate an attribute baselineViewpoints | Reductionist principleHow to How toIdentify focus areas Understand interdependenciesValue prioritisation | Viewpoints Interaction matrixHow to How toUnderstand usage Baseline expectationsOperational profiling | Viewpoints Goal-Question-Metric | Viewpoints 56
  • 56. Baseline provides the basis for future workWhat is to be tested needs to be clear.Remember Functional & Non-functional requirements? Functional Baseline Attribute Baseline Consists of list of features to be tested. The non-functional aspects. Essentially a agreed upon list of features. Agreed upon attributes & their values. 57
  • 57. Tools in D1 -Business value understanding STEM CoreTools Description Concepts System is viewed as a collection of information elements that areHow to Landscaping interconnected. This tool enables you to come up with intelligent questions toUnderstand a system Viewpoints understand the various information elements and their interconnections. Commencing from an external view of end users, various use casesHow to Viewpoints (requirements) are identified and then technical features that constitute theCreate a functional baseline Reductionist principle use cases. This tool enables you to clearly setup a functional baseline that is used as a basis for strategy, plan, design, tooling, reporting & management. In addition to functional correctness, it is imperative that the attributes areHow to Attribute analysis met,. This tool enables you to identify the attributes and ensure that these areCreate an attribute baseline Viewpoints testable. All requirements/features are not equally valued by the end users. This toolHow to Viewpoints allows you to rank the end users, requirements, features thereby enablingIdentify focus areas Value prioritisation prioritisation of testing based on the risk and perceived value. Understanding the real life usage profile is about knowing what operations,How to Viewpoints #concurrent operations, rate of arrival are in progress at a point in time. ThisUnderstand usage Operational profiling tool allows to arrive at the closer to reality potential usage profile of the system to ensure effective non-functional tests. Understanding how a feature/requirement affects/is-dependent on otherHow to Interaction matrix feature/requirements is useful to understand impact & re-testing effort. ThisUnderstand interdependencies tool allows you to rapidly understand the interdependencies.How to Viewpoints This tool allows to derive cleanliness criteria that reflect the expectations.Baseline expectations Goal-Question-Metric 58
  • 58. Customers & End Users Customers in End users Kids Education Seniors Product Artists Drawing e.g Pencil Draftsmen Management Corporate Engineering AdminA product or an application may be sold in different market places made up of different kinds of customers.Each class of customer may have different types of end users who use the product.It is important to understand that each end user may have different needs & expectations.Testing is about ensuring that the product will indeed satisfy the variety of needs & expectations 59
  • 59. Needs & Expectations NEEDS Customers in End users Should write Should have a eraser Kids Education EXPECTATIONS Should be attractive Seniors Should be non-toxic Lead should not break easily Product Artists Drawing e.g Pencil NEEDS Draftsmen Should write Should not need sharpening Management EXPECTATIONS Corporate Thickness should be consistent Variety of thickness should be Engineering available Variety of hardness should be Admin availableNeeds typically features that allow to get the job done.Expectations are how well the need is satisfied.Remember Functional & Non-functional requirements ? 60
  • 60. Customer Profile Customer #1 Customer #2 Customer #3 Customer #4 Different customers have different types of end users, and differing number of users for type of end user. 61
  • 61. Customer Profile & Usage How many What does each one use? What types users What is order of importance? of users What is the usage frequency? F1 F2 F3 F4 System F5 F6 F7 F8 Different end users may use the system differently in terms of what they use, frequency of usage and how they value each each feature. 62
  • 62. Business ValueUltimately end users need the system to do their jobBETTER, FASTER, CHEAPER and deliver value to their customers.Understand that it is about “business value” of system - how does the systemhelp my business to do BETTER, FASTER, CHEAPER. 63
  • 63. Discipline #2 : Defect hypothesis 64
  • 64. Discipline #2 : Defect hypothesisHow to This discipline enables one to hypothesise potential defect types that may be present in the systemHypothesise defects under test and setup a clear goal approach to detection/prevention. Goal focused approach implies that we map the hypothesised potential defect types (PDT) to the elements-under-test i.e feature/Negative thinking | EFF model | requirements.Defect centricity principle This discipline consists of TWO tools, each of which uses certain STEM core concepts to ensure these are done in a scientific and disciplined manner.How toSetup goal-focus Hypothesis is done by scientifically examining certain properties of the system and can be complemented by ones experience.Orthogonality principle 65
  • 65. Tools in D2 - Defect hypothesisTools STEM Core Concepts Description Hypothesis is done by examining properties of the system in a scientific manner. Examining properties of elements that make up the Negative thinking system from five aspects (data, business logic, structure, environmentHow to EFF model and usage) from three views (error-injection, fault-proneness andHypothesise defects Defect centricity principle failure) allows you to scientifically come with potential defects. Subsequently grouping similar potential defects, we arrive at potential defect types (PDT). Mapping the PDT to the elements of the system enables you to beHow to Orthogonality principle clear as to what type of defect you want to in each element enablingSetup goal-focus you to be goal-focused. 66
  • 66. “Properties of the system” End user expectations Cleanliness criteria “affected by” Issues in specifications,Potential Defect Types (PDT) structure, environment and behaviour 67
  • 67. “Properties of the system”Expectations Cleanliness criteria Needs Features “impedes”Environment Behavior Structure Potential Defect Types (PDT) Material Expectations delivered by Needs (Requirements) via Features that display Behavior constructed from Materials in accordance to a Structure in a given Environment 68
  • 68. Setting up a Clear GoalBefore we invest effort in devising a test strategy, plan & test cases,let us be clear about the goal...What types of defects are we looking for? D8 D1 S6 S1 Analysis & Business value management understanding Assess & Understand ANALYSE EXPECTATIONS D7 D2 Execution & Defect reporting 32 core hypothesis D8 D1 concepts D2 Strategy & Tooling D7 Visibility S5 Understand planning SUPPORT STEM CONTEXT S2 D6 D3 D3 D6 Tooling Test design D5 D4 D5 D4 Devise Formulate PROOF HYPOTHESIS What types of defects may be present? S4 S3 i.e. what types of fishes to catch 69
  • 69. Potential Defect Types Functional CLEANLINESS CLEAN Entity implies + Attribute CLEANLINESS What types of defects will affect my 1. Functional behavior 2. Attributes affects Potential Defect Types(PDT) Cleanliness criteria 70
  • 70. Potential Defect (PD) & Potential Defect Type (PDT) We may come up with a variety of potential defects for an entity-under-test. A set of similar potential defects (PD) may be grouped into class of defects i.e Potential Defect Type (PDT). The intent is to create a set of smaller set of classes of defects to uncover. Example: PDT1 PDT1 : User Interface Issues PD1: Spelling mistakes in UI PD1 PD2 PD2: UI elements not aligned PD3 PD3: UI standards violated 71
  • 71. Information used for hypothesis used to hypothesise Intended Functionality Attributes Expectations Potential Defect Types Defect history Personal experience 72
  • 72. Aspects used to hypothesise Data The two broad areas of validation for any entity-under-test are : ‣Functionality ‣Attributes uses Our objective is to ensure that the functional aspects of the system are correct and that they meet the expected attributes. used by So, how can we hypothesise potential defect types for a given entity- Usage Business Logic under-test? In this discipline of HBT, we decompose the entity into FIVE built using elemental aspects that are: ‣Data ‣Business logic ‣Structure Structure ‣Environment ‣Usage uses, lives in i.e. A feature is used by end user(s) and implements the behavior via business logic that is built using structural materials that uses resources from the environment. Environment 73
  • 73. Views on these Aspects Each “Aspect” can be viewed from THREE angles. Error injection What errors can we inject? ERROR irritates FAULT Fault proneness What inherent faults can we “irritate”? FAULT propagates resulting in FAILURE Failure What failures may be caused? 74
  • 74. Aspects & Views Combined Error injection Fault proneness Failure What kinds of erroneous data What kind of issues could data What kinds of bad data can be Data may be injected? cause? generated? What conditions/values can be How can conditions be messed What can be incorrect results Business Logic missed? up? when conditions are combined? How can we setup incorrect How can structure mess up the What kinds of structure can Structure “structure”? behavior? yield incorrect results? What is incorrect environment How can resources in the How can environment be Environment setup? environment cause problems? messed up? In what ways can we use the What kinds of usage may be be What can be poor usage Usage entity interestingly? inherently faulty? experience? 75
  • 75. Generalised PDTs for “Data” Aspect 76
  • 76. Generalised PDTs for “Business Logic” Aspect 77
  • 77. Generalised PDTs for “Structure” Aspect 78
  • 78. Generalised PDTs for “Environment” Aspect 79
  • 79. Generalised PDTs for “Usage” Aspect 80
  • 80. TWO Important Core Concepts used inDefect Hypothesis Negative Thinking EFF (Error-Fault-Failure) model ASPECT oriented approach View oriented approach. Data Error injection uses used by Business Usage Logic Fault proneness built using Structure Failure uses, lives in Environment In real life usage, we combine both of these. 81
  • 81. How to write PDTs“Language shapes the way we think.”Hence it is necessary to have a simple and structured approach to documenting the PDTs identified.When writing PDTs, commence the sentence with“That the system/entity may/may-not....”Write this in defect oriented form.Write each PDT as a sentence.Do not be verbose.e.g.That the system may accept data out of bounds.That the system may leak resources. 82
  • 82. Discipline #3 : Strategy & Planning 83
  • 83. Discipline #3 : Strategy & PlanningHow to This discipline enables to adopt a structured and disciplined approach to formulating a goal-focusedIdentify scope strategy, estimating effort and then formulating a plan. In HBT strategy is defined a clear combination of what to test, when to test, how to design scenarios for test and finally test. This isCycle scoping defining the scope of test, types of test, quality levels, test techniques for design and what tooling support is need to execute the strategy.How toFormulate strategy This discipline consists of SIX tools, each of which uses certain STEM core concepts to ensure these are done in a scientific and disciplined manner.Orthogonality principleQuality growth principleProcess landscapeTechniques landscapeHow to How toFormulate cycles Estimate effortCycle scoping Defect centred activity breakdownQuality growth principle Approximation principleHow to How toAssess tooling support Setup criteriaTooling need analysis Gating principle 84
  • 84. Tools in D3 - Strategy & PlanningTools STEM Core Concepts Description The focus of this tool is allow you to clearly identify the scope of testing that How to Cycle scoping is expected of you by identifying the types of tests i.e. PDTs that you areIdentify scope expected to uncover. Orthogonality principle Strategy is about identifying levels of quality, types of tests, test techniques forHow to Quality growth principle ensuring adequacy and the mode of execution of cases. This tool enables youFormulate strategy Process landscape to approach a disciplined approach to developing a goal-focused strategy that Techniques landscape will be effective & efficient Leveraging technology to develop custom tooling and automating scenarios isHow to key to improving efficiency and effectiveness.This tool enables you to clearly Tooling need analysisAssess tooling support identify the tooling & scripting requirements to you leverage your investment in tooling & automation. Using PDTs as the basis, this tool enables a logical way to estimate effort. Having identified PDTs and mapping this to the elements-under-test and Defect centred activityHow to identifying the types of test to uncover these and deriving #cycles of test by breakdownEstimate effort scoping out cycles, this tool proceeds to estimate the effort for each element- Approximation principle under-test for each type of test for every cycle and sums these to arrive at the potential total effort. Formulating cycles requires a clear focus of the scope of every cycle. This toolHow to Cycle scoping enables you to be clear as to what PDTs you plan to uncover at differentFormulate cycles Quality growth principle points in time of the development in line ensuring that the quality growth is in accordance with the quality levels. Effective & efficient testing implies that good defects are indeed are found theHow to Gating principle right stages of software development. This tool enables setting criteria forSetup criteria each stage of development and release. 85
  • 85. Es C ti m l ea at rp io l n, an o In f fra Sch st ed acti o Planning ru u ct ling n ur e wo rk En su r i Au Te ng h to s i m t te gh c at Design io chn ove n ar ique rage Strategy should help in ch s ite ct ur e C os te W f ha C fect ti y ive s m cle e an plan xec ua n u Execution l/a ing tion ut om at ed ? M St et ay ric in H s- go ow W n t to hat rack in te & w rp re hen Assessment t86
  • 86. Contents of a test strategy Features to focus on List down major features of the product. Rate importance of each feature(Importance = Usage frequency x Failure criticality). Potential issues to uncover Identify the PDTs that you look forward to detecting. Quality Levels Identify the levels of quality that are applicable and map the PDTs to these levels. Tests & Techniques State the various tests that need to be done to uncover the above PDTs. Identify the test techniques that may be used for designing effective test cases. Execution approach Outline what tests will be done manually/automated. Outline tools that may be used for automated testing. Test metrics to collect & analyse Identify measurements that help analyse the strategy is working effectively. 87
  • 87. Goal-focused strategy L4 ... WHAT PDTs to be uncovered WHEN (Quality Levels) and PDT10 TT8 HOW(Test Types)? PDT9 TT7 Key tests L3 PDT9 TT6 L9 End user valueCleanliness End to End Flow test PDT8 TT5 PDT7 L8 Clean Deployment SI, Migration, Compatibility TT4 L2 PDT6 L7 Attributes met LSPS, Security, Usability, PDT5 Reliability, Volume TT3 L1 PDT4 L6 Environment cleanliness “Good citizen” test PDT3 TT2 PDT2 L5 Flow correctness Flow correctness test PDT1 TT1 L4 Behaviour correctness Functionality, Data integrity Stage L3 Structural integrity Structure test In HBT, there exists NINE quality L2 Input interface cleanliness UI test, Usability levels, with certain PDTs to be uncovered at each level. L1 Input cleanliness Data validation test 88
  • 88. Discipline #4 : Test designHow to This discipline enables one come with scenarios/cases that can be proven to be adequate. DesignModel behaviour of scenarios/cases uses a model based approach with some of a tool to enable to help you build the behavioural model and subsequently generating test scenarios/cases from the model ensuringBox model these are “countable” (i.e can be proved to be sufficient) and traced to faults (i.e. has the powerTechniques landscape the uncover the hypothesised defects).Operational Profiling This discipline consists of THREE tools, each of which uses certain STEM core concepts to ensure these are done in a scientific and disciplined manner.How to This tools in this discipline pay a lot attention of the form& structure of test cases and theseDesign scenarios & cases conform to the HBT test case architecture. The structure of test cases is seen as crucial to ensure adequacy and ensure optimality..Behaviour-Stimuli approachTechniques landscapeInput granularity principleHow toEnsure adequacyComplexity assessmentCoverage evaluation 89
  • 89. Tools in D4 - Test designTools STEM Core Concepts Description This tool enables you to understand the intended behaviour of the element- Box model under-test and create a behaviour model to ensure that the scenarios & casesHow to Techniques landscape subsequently designed are indeed complete. This commences by identifyingModel behaviour Operational Profiling conditions that govern behaviour and the data elements that drive the conditions. This tool enables you to design scenarios & cases that can be proved to be adequate. Scenario in HBT is a path or flow of a given behaviour while a testHow to Behaviour-Stimuli approach case is a combination of data (stimuli) that makes the system take that path.Design scenarios & Techniques landscape The focus is ensuring that number of scenarios can be proven to becases Input granularity principle “countable”( i.e. no-more or no-less) and therefore the test cases too are indeed countable. This tool enables you to ensure the designed scenarios/cases are indeed adequate. Tracing scenarios/cases to PDTs enables “Fault coverage” i.e.How to Complexity assessment ensuring the PDTs hypothesised can indeed be in covered. In conjunctionEnsure adequacy Coverage evaluation with “Countability”, the adequacy can indeed be proved in a logical manner. This tool can be also be review/assess completeness/adequacy of existing scenarios/cases. 90
  • 90. Objective of test design Test design is a key activity for effective testing. This activity produces test scenarios/cases. The objective is to come with complete yet optimal number of scenarios/cases that have the power to uncover good defects. Do we have a net that is broad, deep, strong, with small enough holes to catch the fishes that matter? 91
  • 91. Effecting testing is the outcome of good test cases.Therefore the design of test cases plays a crucial role to deliver clean software. Based on the fishing analogy. test cases isthe “net” to catch the “fishes” (defects) and it is necessary that the net needs to be broad, deep, strong with a fine mesh.In HBT, the test design activity is done quality level-wise and within each level stage-wise. At each level it is done in twostages - design test scenarios first and then test cases. Test scenarios are designed into entity-wise and therefore there isa built-in notion of requirements traceability. In addition to requirements traceability, it is expected that the testscenarios and the corresponding test cases are indeed traced to the potential types of defects that they are expected touncover. This is termed as fault traceability.The act of test design commences with the identification of the test level and then the specific type of test for which thetest cases are to be designed. This allows us to identify the various test entities for which test cases have to be designed.Having identified the test entities it is then required to partition the problem into two parts: firstly to understand thebehaviour (business logic) and then to understand the various data elements for the business logic. This allows us toidentify the various conditions in the business logic and allow us to model the behaviour more formally. The behaviourmodel is used to generate test scenarios. Then for every given scenario, we have to understand the data elements thatvary and then come up with the optimal number of values for each data element. The various values of each data elementare then combined to generate the test cases.Note that only external specification and therefore black box techniques have been used until now to design the scenariosand cases. It is equally necessary to use the structural information of the entity in the test to refine the scenarios and testcases.Finally we have to trace the scenarios and the corresponding test cases to the potential defects that have beenhypothesized for the entity under test for the given test type. This allows us to ensure that the test cases do indeed havethe power to uncover the hypothesized defects and thereby ensure that the test cases are indeed adequate.The final step involves assessment of the test breadth, depth porosity and thereby be sure the test cases are indeedadequate. 92
  • 92. Approach to test design Remember the NINE quality levels.. L9 End user value The test scenarios/cases are designed level-wise. Note that the entity to be tested at each level may be different. For example at the higher levels, L8 Clean Deployment the entities to be tested are requirements/business-flows, whereas at lowers levels, it may be screens/APIs etc. L7 Attributes met At each level the approach to test design is: .. design test scenarios first and then L6 Environment cleanliness .. come up with test cases L5 Flow correctness L4 Behavior correctness L3 Structural integrity L2 Input interface cleanliness L1 Input cleanliness 93
  • 93. What is a Test Scenario & Test Case?When we test, our objective is to check that the intended behaviour is what is implemented.What do we need to do?For an entity under test, we need to come up with various potential behaviors and check each one of these. That is we need up a set ofscenarios to evaluate the behaviours.Test Scenario reflects a behavior and is the path from the beginning to end.How do we check a behavior?We do this stimulating the behavior with a combination of inputs and check the outputs.Test Case is a combination of inputs to stimulate the behavior.Positive/Negative test scenarios/casesPositive scenario is the expected behavior of the entity under test.Negative scenario is behavior that is not expected of the entity under test.Test cases that are part of positive scenario are positive test cases.Test cases that are part of negative scenario are negative test cases. 94
  • 94. Hierarchical test design For each entity under test, generate test scenarios first, and then test cases. This is Hierarchical Test Design. Combination of the CONDITIONS result in Test Scenarios Business Logic Inputs Is a collection of Outputs conditions Combination of INPUTS result in Test cases 95
  • 95. Information neededfor design Key tests/ Information needed End to End Flow test L9 End user value End user scenarios of usage, End user expectations L8 Clean Deployment SI, Migration, Compatibility Environment (HW, SW, versions), Data volumes/formats, LSPS, Security, Usability,Reliability, Volume L7 Attributes met Usage profile, data sizes, access controls, security aspects and other attribute information as applicable L6 Environment cleanliness “Good citizen” test Environment dependencies & Resource usage info Flow correctness test L5 Flow correctness Behavioral (conditions) & Data specification Functionality, Data integrity L4 Behavior correctness Behavioral (conditions) & Data specification Structure test L3 Structural integrity Information about architecture & code structure UI test, Usability L2 Input interface cleanliness Interface information and User information L1 Input cleanliness Data validation test Data specification info needed 96
  • 96. What to do when requisite information is missing/not-available?When analyzing a specification, look for the conditions that govern thebehavior (business logic) and the data.It is quite possible that all the conditions may not be clearly listed or the values for the conditions are not clearly stated.What is to be done in such cases?It is a cardinal sin to ignore missing conditions!It is imperative that you identify the list of conditions and values that they take.In the case, these are not available, question!The true value of effective testing lies in uncovering the missing information.Note that you have in effect uncovered issues in specification, which is great. 97
  • 97. How do we know that test scenarios/cases are adequate?1. Test Scenarios/Cases shall be COUNTABLE.That is, the number of test scenarios/cases designed shall be proven to no more or no less.This can only be done (a) if the behavior is modeled and scenarios generated and (b) values for test inputs generated and combinedformally.2. There shall exist scenarios/cases for each requirement/featureREQUIREMENTS TRACEABILITY.3. Each type of defect (PDT) hypothesized for every requirement/feature shall traced to scenarios/cases.FAULT TRACEABILITY4. At the lower level, scenarios/cases shall cover all the code (statements or conditions or multiple-conditions or paths)CODE COVERAGE Countable Scenarios/Cases Feature = Business Logic + Data Business logic is implemented as a set of conditions that have to be met For a given test entity, do we clearly understand ‘all the conditions’ that govern the behavior. Have all ‘effective’ combinations been combined to generate the test scenarios? Do we clearly understand the specification of each test input (data)? Have we generated all the values for each input? Have we combined these values optimally? 98
  • 98. Requirements traceability Requirement traceability is about ensuring that each requirement does indeed have test case(s). So after R1 TC1 we design test cases, we map test cases to requirements to ensure that all the requirements are indeed being validated. This is typically used as a measure of test adequacy. R2 TC2 Let us consider a situation wherein there is exactly one test case for each requirement. Now are the test cases adequate? No! Requirement traceability is a necessary condition for test adequacy but not R3 TC3 sufficient. ... ... Also understand that the expectation of a requirement is not merely about functional correctness, it is also expected that certain attributes i.e. non-functional aspects have to be also met. So non-functional test cases need to be traced too. Rm TCiEvery test case is mapped to a requirement.orEvery requirement does indeed have a test case 99
  • 99. Fault traceability PDT1 R1 Having hypothesized the PDTs (Potential Defect Types) in Stage #3, the natural thing to do would be to map these to the Requirement (or entity-under-test). This is accomplished as part of Stage #4 to PDT2 R2 develop the test strategy. Continuing further in Stage #4 the specification of the Requirement is used to design test scenarios PDT3 R3 and cases. Note that by in this approach, test cases are automatically traced to Requirements. ... ... Given that the Requirement could have the PDTs that have been mapped earlier, let us map the designed test cases to the PDTs. The intent of this is to ensure that the designed test cases do have the power to uncover the hypothesized defects. PDTi Rm Mapping the PDTs to each Requirement and its associated Test cases is termed Fault Traceability in HBT. TC1 PDT1 Fault Traceability in conjunction with Requirements Traceability makes the condition for test adequacy Necessary and Sufficient TC2 PDT2 TC3 PDT3 ... ... TCn PDTi 100
  • 100. Fault traceability + Requirements traceability Requirements traceability is “Necessary but not sufficient” Fault Fault traceability traceability Assume that each requirement had just one test case. This implies that we have satisfied the required traceability objective. PD1 R1 TC1 PD1 What we do know is that could there additional test cases for some of the requirements? PD2 R2 TC2 PD2 So requirements traceability is a necessary condition, not a sufficient PD3 R3 TC3 PD3 condition. ... ... ... ... So, what does it take to be sufficient? PDn Rm TCi PDn If we had a clear notion of types of defects that could affect the customer experience and then mapped these to test cases, we have Requirements Fault Traceability). This allows us to be sure that our test cases can traceability indeed detect those defects that will impact customer experience. 101
  • 101. Test design documentation Useful to clarify intent/ setup goalTest objective Questions: Useful to setup test environmentPrerequisites What is the value of each of these information?Test data combination i.e. How useful are they?Expected results What do these various pieces ofTest steps Useful to detect defects information help in? Useful in manual execution and assist in automating scripting 102
  • 102. Syntax of test case documentationTest objectiveDescribe the test objective in natural language.PrerequisitesDescribe the prerequisites in natural language.Test scenario descriptionWrite this as a ‘one-sentence beginning with“Ensure that system does/does-not...”Test casesFor each scenario list the test cases as a table show below.Test steps/procedureDescribe the procedure for execution as a series of steps.1 ....2 ....Note:Be as terse as possible and yet be clear. The intent should be think more rather than document more. Also terseness forces clarity toemerge. 103
  • 103. HBT Test Case Architecture Organized by Quality levels sub-ordered by items (features/modules..), segregated by type, ranked by importance/priority, sub-divided into conformance(+) and robustness(-), classified by early (smoke)/late-stage evaluation, tagged by evaluation frequency, linked by optimal execution order, classified by execution mode (manual/automated) A well architected set of test cases is like a effective bait that can ‘attract defects’ in the system. In HBT, we pay attention to the form and structure of the test cases in addition to the content. The form and structure as suggested by the HBT test case architecture also enables existing test cases to be analyzed for effectiveness/adequacy. This can be done by “flowing the existing test cases” into the “mould of HBT test case architecture”. 104
  • 104. Discipline #5 : ToolingHow to Tooling and automation is not simply developing code, it requires a clear analysis and design toAnalyse tooling needs ensure that the tooling/automation is flexible enough to keep up with the changes of the system and that it delivers value. This discipline enables you to analysis the tooling needs in a rationalTooling needs analysis manner to ensuring that investment in tooling is not wasted and that the subsequent scripts doAutomation complexity analysis allow up improve efficiency and effectiveness. This discipline consists of TWO tools, each of which uses certain STEM core concepts to ensure these are done in a scientific and disciplined manner.How toGood scriptingSeparation of concernsMinimal babysitting principle 105
  • 105. Tools in D5 - ToolingTools STEM Core Concepts DescriptionHow to Tooling needs analysis This tool enables you to understand what parts of testing needs support ofAnalyse tooling needs Automation complexity analysis technology in terms of tooling/automation. A script once developed has to be in sync with the application/system and hence requires continuous maintenance. Also a script when run may encounter situations that cause to stop or seek user guidance forHow to Separation of concerns continuance. This tool enables you to develop good scripts by ensuring a clearGood scripting Minimal babysitting principle separation of data and code and design of “execution run flow” (i.e what script needs to be executed in case this fails) to ensure that the automated run is maximised (i.e. as much of scripts are indeed run). 106
  • 106. Discipline #6 : VisibilityHow to This discipline enables one to “quantify quality” to enables goal-focused approach to management.Measure quality The focus of this discipline is to setup a model for measuring quality and also devise measures that are purposeful and goal-focused.Quality quantification model This discipline consists of TWO tools, each of which uses certain STEM core concepts to ensure these are done in a scientific and disciplined manner.How toDevise measuresGoal-Question-MetricMetrics landscape 107
  • 107. Tools in D6 - VisibilityTools STEM Core Concepts Description This tool enables you to set a model to measure the “intrinsic” quality byHow to enabling to use the “cleanliness criteria” to give a objective picture of the Quality quantification modelMeasure quality system quality. This also allows you to come with “cleanliness index” to quantify quality. This technique ensures that that you design measures that are goal-focused.How to Goal-Question-Metric rather than setting my measures and then analyzing them, this tool helps youDevise measures Metrics landscape articulate a goal and then derive appropriate measures. 108
  • 108. Discipline #7 : Execution and reportingHow to This discipline enables one to ensure that the reporting of information during testing conveys theGood defect reporting information that enables purposeful actions to be executed.Defect rating principle This discipline consists of TWO tools, each of which uses certain STEM core concepts to ensure these are done in a scientific and disciplined manner.How toLearn & ImproveContextual awareness 109
  • 109. Tools in D7 - Execution and reportingTools STEM Core Concepts Description This tool helps you report the outcomes of testing i.e. defects in a clearHow to Defect rating principle manner to enable (1) clear understanding problem (2) enable clear resolutionGood defect reporting (3) provide learning opportunities for improvement The act of a-priori plan/design is useful to the way, but learning from act ofHow to testing by being understanding the context is very essential to effective Contextual awarenessLearn & Improve testing. This tool is about sensitizing you this so that the test artefacts are continually enhanced with learnings from testing. 110
  • 110. Discipline #8 : ManagementHow to This discipline takes a “earned value approach” to management (i.e. goal focused). The focus is onGoal focused management using the cleanliness criteria and index as the basis to ascertaining where we are with respect to quality in comparison with where we-should-have-been and then ascertaining risks related toQuality quantification model quality & release to enable rational & clear management.Gating principle This discipline consists of ONE tool, that uses certain STEM core concepts to ensure these are done in a scientific and disciplined manner. 111
  • 111. Tools in D8 - ManagementTools STEM Core Concepts Description The tool uses the cleanliness criteria and index to understand as where you are with respect of the goal. Remember that we commenced with setting upHow to Quality quantification model cleanliness criteria and quality levels. This tool adopts a “earned valueGoal focused Gating principle approach to quality” by enabling you to assess as where you in the qualitymanagement level and helps you compare as to where you should be, helping you clearly understand the gaps and enable you to manage rationally/objectively. 112
  • 112. STEM Core Concepts 113
  • 113. A guideline that lists the set of test designTechniques Landscape techniques based on method of examination, design stage and the type of defect.Black Box TechniquesScenario design Data value Test case generation This is a guideline that lists the various test techniques to allowFunctional test generation Exhaustive you to choose the appropriate ones. Decision table Boundary value Single fault Flowchart analysis At least once The techniques are classified into two categories. The first State machine Equivalence Orthogonal array categorisation is based on the type of information used to partitioning (Pair-wise design i.e. external information i.e. Black box and InternalNFT (LSPS) Special value combination) information i.e. white box. The second categorisation is based Operational profiling Error based on test design outcome - (1) Those are useful for designing test scenarios (2) Those useful to create various test data (3) Those that are useful to combine the test data optimally yet beingWhite Box Techniques effective.Control flow based Data flow basedCyclomatic complexity Data flow (def-use)Statement coverage Resource basedDecision coverage Resource leakMultiple condition coveragePath coverage 114
  • 114. A technique to rapidly understand the systemLandscaping by examining the various elements and the connections between them. This technique inspired by Mindmapping enables one to meaningful questions in a systematic manner to understand the needs & expectations. It is based on the simple principle: “Good questions matter more than the answers. Even if questions do not yield answers, it is fine, as it is even more important to know what you do not know.” The premise is that understanding about SIXTEEN key information elements and their connections enables one to understand the expectations & system. The act of seeking information results in questions that aid in understanding. 115
  • 115. Typical questions generated by Landscaping (1/2)Marketplace What marketplace is my system addressing? Why am I building this application? What problem is attempting to solve? What are the success factors?Customer type Are there different categories of customers in each marketplace? How do I classify them? How are their needs different/unique?End user (Actor) Who are the various types of end users (actors) in each type of customer? What is the typical/max. number of end-users for each type? Note: An end user is not necessarily a physical end user, a better word is ‘actor’Requirement What does each end user want? What are the business use cases for each type of end user?(Use case) How important is this to an end user - what is the ranking of a requirement/feature?Attributes What attributes are key for a feature/requirement to be successful (for an end user of each type of customer)? How can I quantify the attribute i.e. make it testable?Feature What are the (technical) features that make up a requirement (use-case)? What is the ranking of these? What attributes are key for a successful feature implementation? How may a feature/requirement affect other feature(s)/requirement(s)? 116
  • 116. Typical questions generated by Landscaping (2/2)Deployment environment What does the deployment environment/architecture look like? What are the various HW/SW that make up the environment? Is my application co-located with other applications? What other softwares does my application connect/inter-operate with? What information do I have to migrate from existing system(s)? Volume, Types etc.Technology What technologies may/are used in my application? Languages, components, services...Architecture How does the application structure look like? What is the application architecture?Usage profile Who uses what? How many times does a end user use per unit time? i.e. #/time At what rate do they use a feature/requirement? Are there different modes of usage (end of day, end of month) and what is the profile of usage in each of these modes? What is the volume of data that the application should support?Behavior conditions What are the conditions that govern the behavior of each requirement/feature? How is each condition met - what data (& value)drives each condition? 117
  • 117. See the system from various end users’ point of view to identify theViewpoints needs & expectations to set a clear baseline. Good testing requires that the tester evaluate the system from the end use angle i.e. put oneself in the end-user’s shoes. This is easier said than done. Viewpoints is a technique that enables this. This states that for each type of user: m 1.Has different expectations from the system Syste 2.Uses different features due to differing needs 3.Values different attributes 4.Views importance of a feature differently 5.Uses features at different frequency/rate 6.Has different expectations on quality One the various types of users are identified, this technique is useful in digging deeper to get a clear handle on needs & expectations. 118
  • 118. Manage complexity by decomposing theReductionist principle information to smaller elements. Customer End User Reductionism means reduction, simplification. The objective of this principle is to breakdown an aspect into smaller parts until it is System Functionality understood clearly. The intent is to gain crystal-clear clarity to enable a job to be performed well. Requirement #1 Feature #1 This principle can be applied at various phases of evaluation to Requirement #2 understand various aspects: Feature #2 Phase Application of this principle Requirement Attributes Break down the system needs into into use cases, Product then features. Functionality Measure #1 understanding Break down the requirements into functional and non-functional aspects. Attributes Measure #2 Break down the entity under test into business Test design logic and data components to design functional test scenarios/cases. Engineering Complexity Break down complexity into functional, structural, assessment data and attribute complexity. Feature Effort Break down large activities into smaller fine-grained estimation activities so that effort can be estimated precisely. Business logic Data 119
  • 119. Reductionist principle (continued) The principle is to break down anything into a smallest component. The intention is to gain a better understanding. So, if you are trying to understand a product,decompose the product into requirements (aka use-cases). Subsequently decompose each use- case into various constituent features. Decompose the given requirement/feature into functional and non-functional aspects. Decompose the functional aspect of a feature into business logic and data. In the case of estimation, decompose the act of validation into large grained test life-cycle activities and then break each of these into smaller grained activities. To understand the complexity, decompose the complexity into functional behavior complexity, structural complexity (how complicated are the innards), attribute complexity (what aspects of non-functional behavior are challenging) and data complexity ( size/volume and data inter- relationship). 120
  • 120. Understand the interrelations of the elements -Interaction matrix requirements, features. A system is not a mere collection of distinct features; it is the interplay of the various features that produces value. But this also has an important side-effect, the various features may affect each other in F1 F2 F3 F4 a negative fashion. A highly interacting set of features make the system complex. F1 X X This technique allows us to understand the potential interactions among the features/requirements. F2 X Modifying a feature may therefore may result in an unwarranted side effect. This technique helps to understand the interaction of the various features of the software and therefore hypothesize the F3 X potential unwanted side-effects and therefore formulate an effective strategy of evaluation.It is useful to the inter-relationships quickly initially, rather than elaborate the semantics of the interaction. The F4 X semantics of interaction may be deferred to a point when detailed analysis of a change needs to be done. Understanding the linkages is also useful to appreciate potential side-effects that may affect soem of the key attributes.This is useful in understanding the system complexity and to enable effective strategy formulation and later at optimization of regression tests. 121
  • 121. A technique to identify attributes expected of the systemAttribute analysis and ensure that they are testable.It is not only sufficient that each feature is functionally clean, it is equally important that the associated attributes be also met. The challengingaspect of the attributes that they could be typically fuzzy. Good testing implies that attributes be testable. This implies that each attribute have aclear measure or metric. For example if performance is one such attribute, it is necessary to understand the performance metric for a feature atthe worst case be t<=T, T being the expected performance metric. Rather than commence with identifying attributes for the whole system, identify attributes for each Attribute Metric requirement and then combine these to arrive at system-wide attributes. For each requirement, list the “critical-to-great-experience” attributes. If it is any easier to do this at the level of features, then do so. i.e. A1 a1 identify key attributes for each feature and then arrive at the attributes at the requirement level. Use a standard attribute list like ISO 9126 to ensure that no attributes are missed out. What we have now, is a listF1 A2 b1 of attributes for each requirement. A3 c Attribute What A2 b2 Once the attributes for each requirement or feature A1 F1(a1),F3(a2)F2 have been identified, now group the common attributes A4 d to formulate the system-wide attributes. A2 F1(b1),F2(b2), F3(a3) A1 a2 This enables better clarity of as to what each attribute A3 F1(c)F3 really means ensuring that the attributes or non- A2 b3 functional requirements are indeed testable. A4 F2(d) 122
  • 122. Attribute analysis (continued)It is quite possible that the attributes are descriptive and therefore hazy/fuzzy. It is now important to ensure that every attribute is testable.As a first step identify key characteristic(s) for each attribute. For each characteristic, identify possible measures so that we may come upwith a number/metric to ensure clarity. Now identify a measure for that characteristic and then identify the value expected for this metric. 1. Identify these based on users Attribute 2. Identify these based on usage patterns Characteristic(s) 3.Based on (2) derive technical measures Measure(s) 4. Now connect (3) to (2) ensuring that these reflect expectations that are testable Expected value(s) The benefits of application of this technique are: 1.That we do focus on the non-functional aspects of the system 2.That the non-functional requirements are indeed testable. 3.That we are able to come with up with good questions to extract/clarify non-functional requirements when they are not/ill-stated. 123
  • 123. A technique to prioritise the elements to be validated toValue prioritisation enable effective and effective testing.A typical system consists of multiple use cases(requirements) that are used by different types of users in differing frequencies. The businessimportance of each use case is different and the same is true of the different user types. Since testing is about reducing the business risk toacceptable levels, and accomplishing the same in optimal effort/cost, we need to understand the business importance and criticality of users, use casesand the associated features. This technique enables a logical analysis of prioritisation of value so that test effort is targeted on the right aspects.ApplicationIdentify the various types of users. For each type of type of users, identify the typical number of users for each user type. If the number of users foran user type is large, we may conclude that this user type is indeed important. However, just because the number of users for a given user type islow, we cannot necessary conclude that this user type is not as important. It is important to understand how important this user is to successfuldeployment of the system i.e. Understanding the impact of this user type’s expectations is not met.Now combine the number of users for a user typeand the business impact of this user to successful deployment and arrive at the priority of a user type. Do this for all the user types.In addition to user type prioritisation based, it is necessary that we understand the importance of what a user type does. i.e. what requirements (usecases/business flows) are most/more important. Here again we can apply the same logic that we we applied for each user type. That is, understand thefrequency of usage and the business impact of a incorrectly implemented requirement. Hence it is important to understand what types of users usethe requirement and how many times they use it in a given span of time. Applying the same logic that low frequency usage may not necessarilyindicate that it is a less important requirement, as that requirement may cause severe business loss if it did not work correctly, despite being usedinfrequently.To arrive at the prioritisation of a requirement, one can breakdown the requirement into its constituent technical features and perform a similaranalysis if it is easier to analyse this from the lower level technical requirements.The end point of application of this STEM core concept results in a rational way to arrive at prioritisation of features, requirements and user types.BenefitsThis allows us to develop a test strategy that can indeed can focus on the key aspects more, utilising the effort, time and cost effectively andefficiently. Understanding prioritisation allows us to set the priority of test scenarios/cases to ‣enable optimal regression ‣enable choosing the key test cases to execute in case of constrained time ‣enable correct severity rating of defects e.g. failure of important test cases could result in high severity defects. 124
  • 124. Value prioritisation (continued)User #Users Bus. CriticalityType Understand the business value of the features and their priorities. Effective testing is about reducing business risk to acceptable levels.UT1 n1 V V High This technique helps you rank the various end users, use cases/ features.UT2 n2 HighUT3 n3 V HighReq./Feature Usage Impact freq. Need Must-have, Could-have, Nice-to-haveR1(F1-F3) n1 V V HighR2(F2-F4) n2 High Frequency Heavy, Moderate, LightR3(F4-F6) n3 V High Loss outcome Huge, Moderate, Acceptable 125
  • 125. A technique to identify the usage patterns andOperational profiling hence the load profile.Understanding the rate and number of transactions probably on a real system is critical to ensure that the system is designed well andlater sized and deployed well. Good understanding of the business domain is seen as a key enabler to arrive at the usage profile.Operational profiling is technique that enables one to scientifically arrive at a real life profile of usage. Good understanding of thisconcept alleviates the problem of lack of deep domain knowledge to understand the usage profile. This core concept consists of thesekey aspects: 1. Mode – Represents a time period of usage e.g. End of month, where the usage patterns are distinctive and different. 2. Key operations (features/requirements) used 3. Types of end users associated with the key features/requirements 4. Number of end users for each type of users 5. Rate of arrival of transactionsIn short, for a given mode, identify the end users types and their key operations and then identify the number of users for each type ofuser and then identify the rate of arrival of transaction. Employing this core concept allows us to think better and ask specific questionsto understand the marketplace and the usage profile in a typical and worst-case scenario.The operational profile is extremely useful for creating test scenarios for load, stress, performance, scalability and reliability tests.So, the profiling would consist of identifying various actors, the various use-cases these actors use the frequency (rate), at which theyuse and understand the no. of operations that they would do in different time periods. 126
  • 126. Operational profiling (continued) Time UT1 O1 User type #Users Operation t1 t2 t3 t4 O2 n1 O1 50 20 30 20 UT1 n2 O2 25 0 15 10 O3 UT2 n3 O3 100 50 15 0 O4 Software/ UT2 n4 O4 0 35 35 50 O5 System UT3 O6 200 O7 150 O8 1001. Identify the key operations of the system 502. Connect the user types & operations i.e. what operations are used bywhich user types 0 t3 t4 t1 t23. For each user type list out the typical & maximum number of users4. Identify modes of usage e.g. different times of day/week/month/year O1 O2 O3 O45. For each mode, approximate the number of operations in a given timeperiod for each user type6. Finally approximate the rate of arrival of the operations.NOTE:1. An user need not be a physical user, it could be another system 127
  • 127. GQM A technique to ensure that the goalGoal-Question-Metric (cleanliness criteria) is indeed testable. A technique that helps you to set clear goals. Metrics may be viewed as milestone markers towards the goal. Collecting metrics is easy, the hard part is “how is it useful in helping me reach my goal?” 1. Identify goal (s) first 2. Come up with questions to understand distance from the goal 3. To answer these questions objectively, identify objective measures Goal Vague cleanliness criteria are useless. This technique enables you derive cleanliness criteria that is clear by forcing you identify : Q1 Q2 1. What is cleanliness? (Goal) 2. How do you ascertain the cleanliness? (Question) 3. Ensure that this is less subjective i.e. via objective measure (Metric) M1 M2 M3 M4 128
  • 128. A technique to identify potential defect types basedNegative thinking on “Aspects” of a system The objective is to identify potential defects in the entity under test in a scientific manner by adopting a fault centric approach. The intent is to think ‘negatively’ on various aspects and thereby identify potential defects in the entity under test. Any entity under test, processes data according to certain business logic, is built using structural components, that uses resources from the environment, and is ultimately used by certain classes of end users. To hypothesise potential defects in a entity-under-test, the above generalisation can be applied in a scientific manner. Aspect Generalized PDTs Structure Consuming dynamic resources and not releasing themAspect Generalized PDTs Error/exceptions not handled well or ignoredData Violation of type specification Synchronization issues, deadlock issues, race conditions Incorrect format of data (data layout, fixed vs. Blocking leading to “hanging” when dependent code does not variable length) return Large volume of data Environment Potential defects pertaining to environment may be : High rate of data arrival Improper configuration of settings in environment Duplication of data that is meant to be unique Non-availability of resourcesBusiness Missing conditions & values that govern the Incorrect versions of dependent sub-systems/componentslogic business logic Slow connections Conflicting conditions Incorrect handling of erroneous paths Usage Wrong sequencing of usage Impact on attributes e.g. performance, scalability, Improper disconnects/aborts reliability, security etc. High rate of usage Transaction related issues i.e. multiple operations Large usage volume need to complete, else none should be performed Unauthorized usage i.e. violation of access control Difficult to use i.e. not very intuitive 129
  • 129. A technique to identify potential defect types basedNegative thinking on “Aspects” of a system The objective is to identify potential defects in the entity under test in a scientificAspects manner by adopting a fault centric approach.Data This technique decomposes an entity into FIVE elemental aspects that are: ‣Data ‣Business logicBusiness Logic ‣Structure ‣Environment ‣Usage DataStructure The intent is to think ‘negatively’ on these FIVE aspects and thereby identify usesEnvironment potential defects in the entity under test. used by Business UsageUsage Logic built using Any entity under test, processes data according to certain business logic, is built using structural Structure components, that uses resources from the environment, and is ultimately used by certain classes uses, lives in of end users. Environment 130
  • 130. Generalised PDTs for “Data” Aspect 131
  • 131. Generalised PDTs for “Business Logic” Aspect 132
  • 132. Generalised PDTs for “Structure” Aspect 133
  • 133. Generalised PDTs for “Environment” Aspect 134
  • 134. Generalised PDTs for “Usage” Aspect 135
  • 135. A principle to group similarDefect centricity principle defects into defect types System Levels PDTs A principle to group similar potential defects into potential defect types(PDT). The intent is to create a manageable list of PDTs. 136
  • 136. EFF Model A technique to identify potential defect types by seeing the(Error-Fault-Failure) system from on different “Views”Errors injected into the system irritate faults causing them to propagate and result in failures.Failure is what customer observes. High impact failures are the result of severe faults.EFF enables failure-centric and error-injection-centric thinking to identify potential defects, complementing the fault-centric thinking.Each “Aspect” can be viewed from THREE angles. Error injection What errors can we inject? ERROR irritates FAULT Fault proneness What inherent faults can we “irritate”? FAULT propagates resulting in FAILURE Failure What failures may be caused? 137
  • 137. A principle that clearly delineates qualityOrthogonality Principle levels, test types and test techniques. This principle states that to uncover a defect optimally, you need to identify the earliest stage of detection (i.e. Quality level) and identify the specific type of test and use the most appropriate test techniques (i.e. bait) to ensure that the scenarios & cases are adequate. Defect This allows us to understand the ‣earliest point of detection ‣type of test needed & ‣effective test technique Type i.e. Given a potential defect: 1. What is the earliest point of detection? 2. What type of test needs to be done? Stage/Level 3. What test techniques would be most suitable? ue iq Identifying the levels, the corresponding test types and hn techniques is what constitutes a strategy. cTe 138
  • 138. A principle to setup progressively improvingQuality growth principle levels of quality/cleanliness for an entity under test. QL4 PDT10 Staging quality growth via levels enables clarity of PDT9 defect detection - “what to detect when”. QL3 PDT9 Reaching the “pinnacle of excellence” is like climbing the staircase of quality. PDT8 This also allows us to objectively measure quality. Cleanliness PDT7 QL2 PDT6 PDT5 QL1 PDT4 PDT3 PDT2 PDT1 Stage 139
  • 139. A guideline that lists the various “process”Process landscape models for test design and execution. Process models 1. Disciplined /Structured Design first 2. Ad-hoc/Random/Creative On the fly design 3. Contextual Context based design 4. Historical Past issues based design 5. Experiential Domain based design Defect type Process model DT1 1,4 DT2 2,3 DT3 4 Process model employed must be based on the type of defect to be uncovered. Certain types of defects are best discovered using a disciplined approach while some may rely on the individual’s creativity at the time of testing. Some of the these may rely on pure domain experience while some may better uncovered by a careful analysis of past history of issues and some of them need an good understanding of the context of deployment and usage. 140
  • 140. A technique to analyse the needs of tooling &Tooling needs analysis automation. Tooling needs can be in Test Scenarios Execution tooling needs type Tooling for automating testing costs 1. Structure analysis money. It is necessary therefore ensure to TT1 Manually A.TS1 Not only be be sure of the purpose or the 2. Installation TT2 TT1 manually objective to be achieved. ... 3. Setup/configuration Nice to TT3 This technique enables analysing the B.TS1 automate 4. Data creation tooling needs as to what is to be TT2 ... automated and the reason/benefits. 5. Test execution Guiding aspects to C.TS1 automation 6. Outcome assessment TT3 1. Frequent basic tests ... 7. Behaviour probing 2. Regression oriented 3. Time consuming 4. Effort consuming 5. Requires high skillsA technique to analyse tooling needs in a disciplined manner. 1.First analyse what aspect of test life-cycle needs tooling help. 2.Later analyse what scenarios cannot be executed manually at all. 3.Identify what of those scenarios that can be executed manually would be nice to automate based on suggested parameters i.e. Guiding aspects to automation.. 141
  • 141. A technique to setup goal focused test cyclesCycle scoping with clear scope for each cycle. Test cycle is the point of time wherein the build is validated. It takes multiple test cycles Cycle#1 C1 C2 C4 to validate a product. Each test cycle should have a clear scope. Scope of testing in a cycle is “what needs to be tested and what What features? F1, F2 F3,F4 F1,F2, aspect of cleanliness needs to be evaluated”. { F1, F2,…,Fn} F3,F4 The scope of a cycle in HBT is a Cartesian Scope Scope product of the Features (or Entities) and the x Types of tests to be executed. T1 T1,T2 T1,T2 Test types {T1, T2,…,Tn} T3 Scope = {Features} x {Test types} i.e What features will be tested, what tests will QL3 be done is the scope of a cycle. QL2 QL1 In short the focus of each cycle is uncover certain PDTs enabling a monotonic quality growth in line with the intended quality levels. 142
  • 142. Defect centred A technique to estimate test effort by identifying the various activities required to uncover the potentialactivity breakdown defects in the entity under test. CC PDT QL TT TS Activities Flows QL4 TT5 Design Features QL3 TT4 TT5 Document Screens QL2 TT3 Automate Components QL1 TT1 TT2 ExecuteEstimate effort based on the PDT that have to be uncovered in the various ‘elements’ of the software at different stages.Identify PDTs to be uncovered, stage them, identify tests,breakdown the each test into various activities, estimateeffort at leaf level and then sum them. 143
  • 143. Defect centred activity breakdown (continued) #Elements, #Hrs/wk, #Cycles #Defects #TS #Cycles Understand Execute Log defects Manage Design & Documentation. Review Depends on mode of “doing” Common test cases – Checklist Static /dynamic Automate For a given level, estimate effort based on #BasicElements, #TS, #Cycles, #Defects 144
  • 144. Approximation principle A principle to aid in scientific approximation. The measure whose value is to be approximated is based on a set of parameters each having a varying sensitivity to the outcome, with a formula that binds these. The value of the parameters needs to be hypothesised, if sensitive, needs to be tested and then the formula applied. Iterate based on learning and potential estimated variation. 1.Identify the key parameters 2.Work out the formula 3.Understand which of these parameters are ‘sensitive’ i.e. a small variation can affect outcome grossly 4.Check if the parameters can be broken down further until their values can be estimated correctly 5.Now estimate the value of the parameters 5.1.Guess/Hypothesise based on best judgment 5.2.Test the hypothesis and correct same to a value closer to reality 6.Apply the formula and compute the value 7.Iterate based on learning gleaned out of this approximation cycle/estimated potential variation 145
  • 145. A technique to rapidly understand the intended functionalBox model behaviour of an entity under test by identifying the conditions and then the data and business logic(condition sequencing). Given an entity to be tested, understand the intended behaviour rapidly to generate the behaviour model. Description of business logic 1. Identify the conditions that govern the behaviour first. I1 O1 2. Then identify the data elements that drive the conditions. 3. Finally identify the sequencing of conditions as a flow to understand the business logic (or behaviour) I2 O2 The focus is to extract the conditions and identify the data elements to enable construction of a behaviour model and also to discover unstated/missing behaviour. 146
  • 146. Behaviour-Stimuli (BEST) A technique to design test scenarios and cases ensuing sufficient yet optimal and purposefulApproach test casesTesting is about injecting a variety of stimuli and assessing the behaviour by observing the actual with the expected result. Firstly identify behaviours to be validated and then generate stimuli. A behaviour is denoted by a test scenario while test cases representstimuli. This is a hierarchical approach to test design, this enables clarity, coverage and optimality. O1 Entity under test I1 TS #1 … TS #1 O2 TC #1 I2 TC#2 O3 TC#3 147
  • 147. A principle to identify the data elementInput granularity principle (s) for an entity under test and their specification.The notion of what an input is and therefore its specification is based on the level of testing. The input specification at a lower level is‘fine’ whereas at higher levels, it is ‘coarse’. Fine implies basic data types, whereas ‘coarse’ implies complex/aggregate data types. Understanding this is key to generating test cases appropriate to the level of testing. Coarse Fine 148
  • 148. A technique to understand an entity’sComplexity assessment complexity to identity suitable test techniques. Systems that are complex, demand to be tested more carefully. Complexity Some systems are business logic wise complex i.e. too many conditions and combinations, while some systems are structurally complex. Behavioural complexity Also in certain system the attributes may be demanding and therefore Business logic complexity the complexity may in attributes. Data complexity Complexity can be broken into 1. Functional complexity Attribute complexity 2. Structural complexity 3. Attribute complexity Structural complexity If (1) is complex, black box techniques are useful Logic complexity If (2) is complex white box techniques is useful If (3) is complex, judicious mix of (1) and (2) is necessary Resource complexity 149
  • 149. Coverage evaluation A technique to assess test case adequacy.Adequacy of test cases is key to clean software.This principle helps in understanding the test breadth, depth and porosity of test case.Breadth relates to the various types of tests to uncover the different types of defects.Depth relates to the various levels of tests to ensure that defects at all levels can be uncovered.Porosity is whether test case is a clear combination of data or not.Additionally it is necessary to understand the conformance and defect orientation of test cases. Test breadth Breadth Types of tests Depth Quality levels Porosity Test case “fine-ness” Test depth Test porosity 150
  • 150. Automation complexity A technique to analyse complexity of tooling/ automation analysis The complexity of a script and therefore the effort required to design and code the scripts depends on various parameters. A script consists of sections of code to setup the condition for test, drive the test, compare the outcome, log information and finally cleanup. The complexity of the script therefore may be decomposed into individual section complexities and analysed. Setup Complexity depends on #steps, data, inter-relationship Driver Complexity depends on length of flow (#steps), error-recovery complexity Complexity depends on #comparisons and type of comparison (course versus fine) and whether it is deterministic or Oracle non-deterministic Log Complexity depends on #log points and log information detAILS Cleanup Complexity depends on #steps, data inter-relationship 151
  • 151. A principle to ensure unattendedMinimal babysitting principle automated test runs. Test script #1 When automated tests are run, some of the scripts may fail and abort the entire test Test script #2 cycle. To utilise automation most effectively and increase test efficiencies, it is necessary Test script #3 to maximise the test run. i.e. as many scripts that can be run must be executed. Test script #4 This principle states that the test scripts must be designed in a such a manner that … ‘baby sitting’ i.e. restarting the test run manually must be minimal. Test script #N 152
  • 152. Separation of concerns A principle to ensure delineation of code & data in automation to facilitate robust andprinciple maintainable automation.. Code A script consists of code and data that it uses to drive the system-under- test. The basic attribute of a good script is its ability to be flexible with Common code minimal changes for adaptation. Hence it is necessary that a script does not contain hard-coded data. The data in a script pertains to configuration/setup and the actual test data. This Specific code principle states that there must be a clean separation of the code and data aspects of the script. Data Setup/Config. information Test data 153
  • 153. A technique to “quantify quality” inQuality quantification model alignment with the cleanliness criteria and quality levels.Quantify software quality to allow for better decision making. Software is invisible and quality is the invisible aspect of thisinvisible. This technique enables you to setup an objective measurement system for measuring the quality of software. Rate each cleanliness criteria Represent these as a Kiviat chart Area under a chart for a cycle represent the “Quality Index”. 154
  • 154. A guideline to designing goal oriented metricsMetrics landscape to rationally assess quality, delivery risk and test effectivenessTo know where we are, how we are doing, it isnecessary to have a have a beacon to light up theway to ensure good visibility. “Good goal orientedmetrics is that beacon”. Quality Progress Example : Process Effectiveness: Test breadth, depth, Defect escapes Metrics +:- ratio, Coverage Efficiency: Blockers Productivity: #TC executed/designed Risk Process 155
  • 155. A principle to rate defect severity andDefect rating principle priority.Defects are rated by Severity and Priority.Severity of a defect is decided on by the impact of the defect on the customer.Priority of a defect is decided by the risk posed to timely release. Severity Serious impact implies HIGH severity System Customer Dev team Priority “Business risk” “Release risk” Blocker implies HIGH priority decides ‘Severity’ decides ‘Priority’ 156
  • 156. A principle to learn from context to enableContextual awareness better understanding and increase test effectiveness.Good testing requires keen observation skills and asharp ‘ear to the ground’. Observation of context andlearning from it is key to better understanding andimprovement of test cases.“Familiarity breeds contempt” - Getting familiar withthe internal workings and, and external behaviour goesa long way in significantly enhancing the testeffectiveness. Test cycle Test cases Test cases (after) (before) 157