The document is a walkthrough of using test-driven development (TDD) to solve an encryption problem. It begins by setting up test and source code files. Tests are written based on examples from the problem. Minimal code is written to pass each test. Refactoring improves the code while maintaining passing tests. The implementation is generalized through many small iterative changes. Edge cases are addressed, like when the encryption grid is too small. The completed solution passes all tests.
Seconda serata di introduzione al Test-Driven Development, tenuta in XPeppers a Trento il 24 Ottobre 2012.
Nelle slide c'è anche la descrizione del coding dojo sullo string calculator che abbiamo svolto assieme.
Unit testing and test-driven development are practices that makes it easy and efficient to create well-structured and well-working code. However, many software projects didn't create unit tests from the beginning.
In this presentation I will show a test automation strategy that works well for legacy code, and how to implement such a strategy on a project. The strategy focuses on characterization tests and refactoring, and the slides contain a detailed example of how to carry through a major refactoring in many tiny steps
This document provides an overview of Perl testing with Test::Simple and Test::More. It discusses why testing is important, basic tests with ok(), and more advanced matching functions like is(), like(), and can_ok() provided by Test::More. It also covers controlling test flow using skip(), todo(), diag(), pass(), and fail(). The goal is to introduce Perl testing and help readers feel comfortable writing and using tests.
Refactoring legacy code driven by tests - ENGLuca Minudel
re you working on code poorly designed or on legacy code that’s hard to test? And you cannot refactor it because there are no tests?
During this Coding Dojo you’ll be assigned a coding challenge in Java, C#, Ruby, JavaScript or Python. You will face the challenge of improving the design and refactoring existing code in order to make it testable and to write unit tests.
We will discuss SOLID principles, the relation between design and TDD, and how this applies to your solution.
Reading list:
Growing Object-Oriented Software, Guided by Tests; Steve Freeman, Nat Pryce
Test Driven Development: By Example; Kent Beck
Working Effectively with Legacy; Michael Feathers
Agile Software Development, Principles, Patterns, and Practices; Robert C. Martin (C++, Java)
Agile Principles, Patterns, and Practices in C#; Robert C. Martin (C#)
The document discusses strategies for working with legacy code, which is code inherited from previous developers or older versions that often lacks tests and good documentation. It defines legacy code and outlines challenges like poor structure, dependencies, and lack of tests. It then provides approaches for modifying legacy code like identifying what to change and test, breaking dependencies, writing tests, and refactoring code in small, tested increments. Specific tactics are presented like using seams, sprouting methods, and interfaces to break dependencies and allow testing legacy code. The importance of understanding the system and increasing test coverage before making changes is emphasized.
The document discusses how tests can become messy if certain principles are not followed. It begins with a story of a junior developer writing their first test code, which quickly becomes complicated by dependencies on global states and logging. This leads to brittle, non-isolated tests. The document emphasizes that testable code is not always good code, and production code should not be modified to enable tests. It promotes writing code that is loosely coupled and follows principles like dependency injection to be properly testable. Tests themselves can become messy if they violate DRY and KISS principles through duplication and overcomplication.
Book review: Working Effectively with Legacy Code, by Michael C. Feathers
Agenda
- The mechanics of change
- Changing software
- Dependency breaking techniques
This session is for developers who need to work on code projects that where written without good unit-testing.
Seconda serata di introduzione al Test-Driven Development, tenuta in XPeppers a Trento il 24 Ottobre 2012.
Nelle slide c'è anche la descrizione del coding dojo sullo string calculator che abbiamo svolto assieme.
Unit testing and test-driven development are practices that makes it easy and efficient to create well-structured and well-working code. However, many software projects didn't create unit tests from the beginning.
In this presentation I will show a test automation strategy that works well for legacy code, and how to implement such a strategy on a project. The strategy focuses on characterization tests and refactoring, and the slides contain a detailed example of how to carry through a major refactoring in many tiny steps
This document provides an overview of Perl testing with Test::Simple and Test::More. It discusses why testing is important, basic tests with ok(), and more advanced matching functions like is(), like(), and can_ok() provided by Test::More. It also covers controlling test flow using skip(), todo(), diag(), pass(), and fail(). The goal is to introduce Perl testing and help readers feel comfortable writing and using tests.
Refactoring legacy code driven by tests - ENGLuca Minudel
re you working on code poorly designed or on legacy code that’s hard to test? And you cannot refactor it because there are no tests?
During this Coding Dojo you’ll be assigned a coding challenge in Java, C#, Ruby, JavaScript or Python. You will face the challenge of improving the design and refactoring existing code in order to make it testable and to write unit tests.
We will discuss SOLID principles, the relation between design and TDD, and how this applies to your solution.
Reading list:
Growing Object-Oriented Software, Guided by Tests; Steve Freeman, Nat Pryce
Test Driven Development: By Example; Kent Beck
Working Effectively with Legacy; Michael Feathers
Agile Software Development, Principles, Patterns, and Practices; Robert C. Martin (C++, Java)
Agile Principles, Patterns, and Practices in C#; Robert C. Martin (C#)
The document discusses strategies for working with legacy code, which is code inherited from previous developers or older versions that often lacks tests and good documentation. It defines legacy code and outlines challenges like poor structure, dependencies, and lack of tests. It then provides approaches for modifying legacy code like identifying what to change and test, breaking dependencies, writing tests, and refactoring code in small, tested increments. Specific tactics are presented like using seams, sprouting methods, and interfaces to break dependencies and allow testing legacy code. The importance of understanding the system and increasing test coverage before making changes is emphasized.
The document discusses how tests can become messy if certain principles are not followed. It begins with a story of a junior developer writing their first test code, which quickly becomes complicated by dependencies on global states and logging. This leads to brittle, non-isolated tests. The document emphasizes that testable code is not always good code, and production code should not be modified to enable tests. It promotes writing code that is loosely coupled and follows principles like dependency injection to be properly testable. Tests themselves can become messy if they violate DRY and KISS principles through duplication and overcomplication.
Book review: Working Effectively with Legacy Code, by Michael C. Feathers
Agenda
- The mechanics of change
- Changing software
- Dependency breaking techniques
This session is for developers who need to work on code projects that where written without good unit-testing.
Test Driven Development - Phương pháp phát triển phần mềm theo hướng viết test trước.
Áp dụng TDD sẽ đem lại cho bạn thiết kế phần mềm trong sáng hơn và quản lý được chất lượng từng dòng code của mình viết ra.
Bài trình bày của bạn Lê Anh tại Meetup của Ha Noi .NET Group.
Chi tiết vui lòng xem tại: http://tungnt.net
The document describes an introductory training course on PHPUnit testing. It discusses installing PHPUnit and getting started with writing tests. Specifically, it shows how to write a first test case to test a Game_Grid class by creating a GridTest.php file. It fails initially since the class doesn't exist yet. The test is then made to pass by creating the Grid class file. The document also discusses bootstrapping tests by creating a Bootstrap.php file to autoload classes so requires aren't needed in each test.
TDD introduces the concepts of test-driven development and using NUnit for testing. It outlines the basic steps of TDD: write a failing test first, then just enough code to make it pass, and repeat. Key aspects of NUnit are attributes like [TestFixture] and [Test] to mark classes and methods, and assert methods to validate logic. An example walks through creating a simple test for an account class with a balance that can be set and verified.
We've all been faced with legacy code and often decided to rewrite, feeling it will be easier. There are many reasons this can be wrong. Adam Culp will talks about the entire journey of refactoring a legacy code base. He will begin with assessment and why, move on to planning how and when, cover execution and testing, give step-by-step examples, and even show how to manage the process effectively. Attendees will gain insight and tips on how to handle their own pile of code and refactor happy.
TDD (test-driven development) involves writing unit tests before production code according to three laws: 1) write only enough code to fail a test, 2) write only enough test to fail initially, and 3) write only enough code to pass the test. An example involves testing an add() function by ensuring it handles errors for too few/many arguments and non-numeric values. Benefits of TDD include reduced debugging time, higher code quality, avoiding over-engineering, better interfaces, documentation, and more modular code. Best practices are to keep units small and focused, treat tests as production code, and design for low coupling and isolation.
Working Effectively with Legacy Code: Lessons in PracticeAmar Shah
Code rots. Even the best designs can fall into chaos, weighed down by changing requirements, hard-coded dependencies, and overzealous cut-and-paste. Eventually, the mess has to be cleaned up, but there's just one problem: There are no tests. No one knows exactly what the code is supposed to do. You will think you're fixing it, but instead you'll break it--and you won't even know.
A few months ago, I inherited just such a mess. In this talk, I'll explore Michael Feathers' classic Working Effectively with Legacy Code, a comprehensive and accessible guide to refactoring the even the ugliest, most neglected code bases. Using real examples, I'll explain how Feathers' techniques are working for me.
How to complement TDD with static analysisPVS-Studio
TDD is one of the most popular software development techniques. I like this technology in general, and we employ it to some extent. The main thing is not to run to extremes when using it. One shouldn't fully rely on it alone forgetting other methods of software quality enhancement. In this article, I will show you how the static code analysis methodology can be used by programmers using TDD to additionally secure themselves against errors.
The document discusses Test Driven Development (TDD) in PHP. It provides an overview of TDD, the benefits it provides like high cohesion and loose coupling, and some drawbacks. It then demonstrates a live coding example of TDD in PHP by building a simple integer calculator using PHPUnit for a math tutor application. Resources for learning more about TDD, PHPUnit, and Xdebug are also included.
Test driven development - Zombie proof your codePascal Larocque
This document discusses test driven development and how to write testable code. It recommends writing tests before writing code to prevent "zombie code" that is hard to maintain and change. Specific tips provided include using dependency injection, following SOLID principles to separate concerns, and writing fast, isolated tests using tools like PHPUnit and PHPSpec. Continuous integration is also recommended to prevent technical debt from accumulating.
This document introduces refactoring as a way to improve the design of existing code while preserving its observable behavior. It discusses how refactoring can make code more robust, simple and flexible by addressing issues like fragility, complexity and rigidity. The refactoring process involves choosing a code smell to address, selecting a refactoring technique, applying the change, and verifying with tests. Applying refactoring in small steps can yield great results in making code easier to understand and cheaper to modify. Recommended books and online resources on refactoring techniques are also provided.
San Francisco Software Craftsmanship Meetup
Test Driven Developers Bay Area Meetup
TDD Flow: The Mantra in Action” is a talk + hands-on about the mantra of TDD and its core patterns. Here are some questions for this talk: What is TDD? How to write a good test that fails? How to write code enough to make the test pass? How to remove duplication? How to refactor code? How to create clean code? Is TDD about testing or design? How small should a test be? Should I only write unit tests? Should I estimate TDD? How to use TDD with other agile methods like Scrum, Kanban or BDD? And finally, how to flow in TDD?
The document discusses assessing unit test quality and describes a project called PEA that aims to collect and report metrics around test directness and assertion density. It outlines various approaches tried for PEA, including static code analysis, bytecode instrumentation, aspect-oriented programming, and using a debugger. The preferred approach ended up being to use the Java Platform Debugger Architecture to monitor tests running in another JVM without modifying code.
This presentation introduces the key testing concepts of the PHPUnit testing framework. It discusses unit testing, test cases, fixtures, stubs, mocks, and best practices for organizing and running tests. The presentation emphasizes that unit testing isolates and tests the smallest parts of an application to find errors, facilitate refactoring, and enable automated testing. PHPUnit allows writing tests for PHP code and provides features like data providers, exception handling, and code coverage reports.
The document introduces Test Driven Development (TDD). TDD is a software development process that relies on short development cycles where you write an automated test first, then code to pass that test, and refactor as needed. The key benefits of TDD are that it encourages simple design, validates correctness, and drives the design of a program in a modular way. TDD best practices include writing self-explanatory test assertions, keeping tests small and isolated, integrating code frequently, and following the TDD mantra and rhythm of red-green-refactor.
This document provides an overview of test-driven development (TDD). It defines TDD as a technique for building software where tests are written before code to guide development. The key aspects of TDD covered are:
- Writing tests first before code, which helps improve design and ensures tests are written.
- The TDD mantra of Red-Green-Refactor, where tests initially fail (Red), code is written to pass tests (Green), then code is refactored to improve design.
- An example case study of a large Java project developed using TDD that has over 20,000 lines of unit tests providing over 90% test coverage.
The document provides a summary of a test-driven development walkthrough for a library fine calculation exercise. It outlines setting up the testing framework and files. It then describes the process of writing tests based on requirements, making the tests fail, then passing the tests by implementing minimal code. As more tests are added, the code is refactored to be more generalized through techniques like triangulation. The goal is to use tests to drive the development of production code in a iterative cycle.
This document summarizes a TDD walkthrough for converting times to words. It begins by setting up the necessary files and frameworks. The first test case converts 5:00 to "five o' clock" and fails initially. Code is then written to pass this test. Additional tests are added for other times like 5:30 and 5:15, with code changes to pass each new test while maintaining previous tests. Refactoring removes duplication, leading to cleaner code structure using variables and objects. The walkthrough demonstrates a step-by-step TDD process.
Lightening Talk I gave at Inaka in April 2014.
I was in charge of investigating test-driven development for our iOS mobile team. Since I realized it was such a big concept, after having gathered enough information and having played with it enough, I decided to introduce my fellows on the topic by presenting it in a formal talk with slides. The aim was teaching them a different way of developing, which, for us, at that moment, was completely new and controversial.
Test Driven Development - Phương pháp phát triển phần mềm theo hướng viết test trước.
Áp dụng TDD sẽ đem lại cho bạn thiết kế phần mềm trong sáng hơn và quản lý được chất lượng từng dòng code của mình viết ra.
Bài trình bày của bạn Lê Anh tại Meetup của Ha Noi .NET Group.
Chi tiết vui lòng xem tại: http://tungnt.net
The document describes an introductory training course on PHPUnit testing. It discusses installing PHPUnit and getting started with writing tests. Specifically, it shows how to write a first test case to test a Game_Grid class by creating a GridTest.php file. It fails initially since the class doesn't exist yet. The test is then made to pass by creating the Grid class file. The document also discusses bootstrapping tests by creating a Bootstrap.php file to autoload classes so requires aren't needed in each test.
TDD introduces the concepts of test-driven development and using NUnit for testing. It outlines the basic steps of TDD: write a failing test first, then just enough code to make it pass, and repeat. Key aspects of NUnit are attributes like [TestFixture] and [Test] to mark classes and methods, and assert methods to validate logic. An example walks through creating a simple test for an account class with a balance that can be set and verified.
We've all been faced with legacy code and often decided to rewrite, feeling it will be easier. There are many reasons this can be wrong. Adam Culp will talks about the entire journey of refactoring a legacy code base. He will begin with assessment and why, move on to planning how and when, cover execution and testing, give step-by-step examples, and even show how to manage the process effectively. Attendees will gain insight and tips on how to handle their own pile of code and refactor happy.
TDD (test-driven development) involves writing unit tests before production code according to three laws: 1) write only enough code to fail a test, 2) write only enough test to fail initially, and 3) write only enough code to pass the test. An example involves testing an add() function by ensuring it handles errors for too few/many arguments and non-numeric values. Benefits of TDD include reduced debugging time, higher code quality, avoiding over-engineering, better interfaces, documentation, and more modular code. Best practices are to keep units small and focused, treat tests as production code, and design for low coupling and isolation.
Working Effectively with Legacy Code: Lessons in PracticeAmar Shah
Code rots. Even the best designs can fall into chaos, weighed down by changing requirements, hard-coded dependencies, and overzealous cut-and-paste. Eventually, the mess has to be cleaned up, but there's just one problem: There are no tests. No one knows exactly what the code is supposed to do. You will think you're fixing it, but instead you'll break it--and you won't even know.
A few months ago, I inherited just such a mess. In this talk, I'll explore Michael Feathers' classic Working Effectively with Legacy Code, a comprehensive and accessible guide to refactoring the even the ugliest, most neglected code bases. Using real examples, I'll explain how Feathers' techniques are working for me.
How to complement TDD with static analysisPVS-Studio
TDD is one of the most popular software development techniques. I like this technology in general, and we employ it to some extent. The main thing is not to run to extremes when using it. One shouldn't fully rely on it alone forgetting other methods of software quality enhancement. In this article, I will show you how the static code analysis methodology can be used by programmers using TDD to additionally secure themselves against errors.
The document discusses Test Driven Development (TDD) in PHP. It provides an overview of TDD, the benefits it provides like high cohesion and loose coupling, and some drawbacks. It then demonstrates a live coding example of TDD in PHP by building a simple integer calculator using PHPUnit for a math tutor application. Resources for learning more about TDD, PHPUnit, and Xdebug are also included.
Test driven development - Zombie proof your codePascal Larocque
This document discusses test driven development and how to write testable code. It recommends writing tests before writing code to prevent "zombie code" that is hard to maintain and change. Specific tips provided include using dependency injection, following SOLID principles to separate concerns, and writing fast, isolated tests using tools like PHPUnit and PHPSpec. Continuous integration is also recommended to prevent technical debt from accumulating.
This document introduces refactoring as a way to improve the design of existing code while preserving its observable behavior. It discusses how refactoring can make code more robust, simple and flexible by addressing issues like fragility, complexity and rigidity. The refactoring process involves choosing a code smell to address, selecting a refactoring technique, applying the change, and verifying with tests. Applying refactoring in small steps can yield great results in making code easier to understand and cheaper to modify. Recommended books and online resources on refactoring techniques are also provided.
San Francisco Software Craftsmanship Meetup
Test Driven Developers Bay Area Meetup
TDD Flow: The Mantra in Action” is a talk + hands-on about the mantra of TDD and its core patterns. Here are some questions for this talk: What is TDD? How to write a good test that fails? How to write code enough to make the test pass? How to remove duplication? How to refactor code? How to create clean code? Is TDD about testing or design? How small should a test be? Should I only write unit tests? Should I estimate TDD? How to use TDD with other agile methods like Scrum, Kanban or BDD? And finally, how to flow in TDD?
The document discusses assessing unit test quality and describes a project called PEA that aims to collect and report metrics around test directness and assertion density. It outlines various approaches tried for PEA, including static code analysis, bytecode instrumentation, aspect-oriented programming, and using a debugger. The preferred approach ended up being to use the Java Platform Debugger Architecture to monitor tests running in another JVM without modifying code.
This presentation introduces the key testing concepts of the PHPUnit testing framework. It discusses unit testing, test cases, fixtures, stubs, mocks, and best practices for organizing and running tests. The presentation emphasizes that unit testing isolates and tests the smallest parts of an application to find errors, facilitate refactoring, and enable automated testing. PHPUnit allows writing tests for PHP code and provides features like data providers, exception handling, and code coverage reports.
The document introduces Test Driven Development (TDD). TDD is a software development process that relies on short development cycles where you write an automated test first, then code to pass that test, and refactor as needed. The key benefits of TDD are that it encourages simple design, validates correctness, and drives the design of a program in a modular way. TDD best practices include writing self-explanatory test assertions, keeping tests small and isolated, integrating code frequently, and following the TDD mantra and rhythm of red-green-refactor.
This document provides an overview of test-driven development (TDD). It defines TDD as a technique for building software where tests are written before code to guide development. The key aspects of TDD covered are:
- Writing tests first before code, which helps improve design and ensures tests are written.
- The TDD mantra of Red-Green-Refactor, where tests initially fail (Red), code is written to pass tests (Green), then code is refactored to improve design.
- An example case study of a large Java project developed using TDD that has over 20,000 lines of unit tests providing over 90% test coverage.
The document provides a summary of a test-driven development walkthrough for a library fine calculation exercise. It outlines setting up the testing framework and files. It then describes the process of writing tests based on requirements, making the tests fail, then passing the tests by implementing minimal code. As more tests are added, the code is refactored to be more generalized through techniques like triangulation. The goal is to use tests to drive the development of production code in a iterative cycle.
This document summarizes a TDD walkthrough for converting times to words. It begins by setting up the necessary files and frameworks. The first test case converts 5:00 to "five o' clock" and fails initially. Code is then written to pass this test. Additional tests are added for other times like 5:30 and 5:15, with code changes to pass each new test while maintaining previous tests. Refactoring removes duplication, leading to cleaner code structure using variables and objects. The walkthrough demonstrates a step-by-step TDD process.
Lightening Talk I gave at Inaka in April 2014.
I was in charge of investigating test-driven development for our iOS mobile team. Since I realized it was such a big concept, after having gathered enough information and having played with it enough, I decided to introduce my fellows on the topic by presenting it in a formal talk with slides. The aim was teaching them a different way of developing, which, for us, at that moment, was completely new and controversial.
Why should we use TDD to develop in Elixir? When we are applying it correctly? What are the differences that we can find in a code developed with TDD and in code not developed with it? Is it TDD about testing? Really? In this talk, I'll show what is TDD and how can be used it in functional programming like Elixir to design the small and the big parts of your system, showing what are the difference and the similarities between an OOP and FP environment. Showing what is the values of applying a technique like TDD in Elixir and what we should obtain applying it.
Getting started with Test Driven Development - Ferdous Mahmud ShaonCefalo
Getting Started with TDD discusses test-driven development (TDD). TDD involves writing unit tests before writing code to make the tests pass. This ensures code is testable and bugs are prevented. The document outlines the basic TDD process of writing a failing test, then the minimum code to pass it, and refactoring the code without breaking tests. Uncle Bob's three laws of TDD state you must write a failing test first before code, only code to pass the test, and refactor without breaking tests. Benefits of TDD include cleaner code, testability, reduced bugs, and safer refactoring. The document provides an example of building a simple calculator using TDD.
Getting Started with TDD outlines the principles and process of Test-Driven Development (TDD). TDD involves writing unit tests before writing code to make the tests pass. This ensures code is testable and prevents bugs. The document demonstrates TDD by building a simple calculator, writing tests for addition and division that initially fail, then adding minimal code to pass each test. It emphasizes that TDD helps produce cleaner, more maintainable code through its focus on writing tests first and refactoring code without breaking tests. Benefits of TDD include reduced bugs, safer refactoring, and testable code, while drawbacks include potential overhead for simple projects. The document recommends resources for learning more about TDD and its
The document discusses test-driven development (TDD) and the three laws of TDD. It begins with the author explaining their initial experiences with TDD and some challenges they faced. It then presents the three laws of TDD which state that you must write a failing test before production code, only write enough test code to fail, and only write enough production code to pass the test. The document provides examples of using TDD with small steps and emphasizes writing one test at a time and improving the code base. It concludes by inviting the reader to try TDD and provides some additional resources on transformations and the transformation priority premise.
Ever tried doing Test First Test Driven Development? Ever failed? TDD is not easy to get right. Here's some practical advice on doing BDD and TDD correctly. This presentation attempts to explain to you why, what, and how you should test, tell you about the FIRST principles of tests, the connections of unit testing and the SOLID principles, writing testable code, test doubles, the AAA of unit testing, and some practical ideas about structuring tests.
TDD and Simple Design Workshop - Session 1 - March 2019Paulo Clavijo
The document discusses test-driven development (TDD) and simple design. It introduces TDD and some of its core practices, including test-driven development, simple design, refactoring, and pair programming. It provides an agenda for a workshop that will cover these topics over three sessions, including extreme programming (XP), the four elements of simple design, test doubles, outside-in TDD, and SOLID principles. The workshop aims to communicate best practices for using technical practices to succeed with agile development.
Beyond Testing: Specs and Behavior Driven DevelopmentRabble .
This document discusses testing approaches for software development, including:
1. It begins by describing traditional QA testing from the perspective of a programmer, noting it finds major problems but is extra work.
2. It then introduces the concept of regression testing in code to automatically verify functionality. Unit testing is described as the most common type of regression testing.
3. The document advocates for behavior driven development (BDD) which focuses on testing functionality and desired behavior rather than implementation details, using "should" statements rather than asserts. This helps avoid issues when code changes but functionality does not.
Unit testing involves testing individual units or components of code, such as classes or methods, in isolation from the rest of the code base. A unit test asserts certain conditions or tests for specific behaviors and returns a pass/fail result. The purpose of unit testing is to validate that each piece of code works as intended, allowing code to be refactored with confidence and problems to be identified early. Best practices for unit testing include writing tests for new code, designing code for testability, and following an arrange-act-assert structure. Tests should be fast, isolated, and clearly named. Unit testing promotes code quality, documentation, and easier refactoring.
TDD is a software development practice where tests are written before production code to define requirements. It follows three rules: 1) Write a test that fails without production code. 2) Write just enough production code to pass the test. 3) Refactor code without changing external behavior. This ensures code is properly tested and reduces bugs through frequent integration and refactoring enabled by the test suite. TDD results in testable, loosely coupled code and faster delivery times.
TDD is now mainstream but a lot people don't know or don't remember what is its purpose. TDD is about software design not testing or catching bug. TDD helps developers to shape and create software with "good" design, what is a "good" design is something that we will discuss in the topic.
This document discusses test-driven development (TDD) and behavior-driven development (BDD). It covers the core principles and rules of TDD, including writing failing tests first and then code to pass the tests. The benefits of TDD are described, such as improved design, documentation, and catching errors earlier. Challenges with TDD are acknowledged, but it is argued that with experience writing clean code and following design best practices, TDD can help developers write higher quality code. Tools for writing tests like Hamcrest and AssertJ are also mentioned.
The document discusses the importance of testing code through test-driven development (TDD) and behavior-driven development (BDD). It explains that TDD involves writing tests, watching them fail, making them pass, refactoring, and repeating. BDD is more complex and involves business analysts, developers, and stakeholders specifying desired behaviors as user stories. The document encourages writing unit tests because it allows for quick code changes with confidence, helps understand code design, and documents expected behavior, though it takes time initially.
Unit testing JavaScript code allows developers to make changes quickly and confidently by verifying code works as expected through automated tests. Testacular is a Node.js-based testing framework that runs tests using various browsers and frameworks like Jasmine. It provides features like live reloading, code coverage reports, and integration with continuous integration servers. Writing tests in Jasmine involves describing test suites and individual specs using expectations and matchers to validate code behavior.
Here are some potential caveats with BDD style testing:
1. The framework can feel too "magical" if it uses too much metaprogramming under the hood. The implementation details should not be obscured.
2. Descriptions can become too vague if they only state intentions at a very high level without concrete examples. Tests as documentation only works if the descriptions are clear and specific.
3. There is a risk of duplication if contexts or examples are not properly organized and nested. Descriptions should aim to be DRY.
4. Performance overhead of the framework if it does a lot of runtime reflection or string manipulation. The framework should have a small performance footprint.
5. Tests become brittle
TDD is now mainstream but a lot people don't know or don't remember what is its purpose. TDD is about software design not testing or catching bug. TDD helps developers to shape and create software with "good" design, what is a "good" design is something that we will discuss in the topic.
Many developers know that they should be writing tests for their apps. However, it’s often hard to know how to get started or to convince your manager that you should be spending half of your time writing and maintaining test code. In this talk, you will learn how you can integrate testing into your day-to-day workflow and you’ll learn why a good test suite will not cost you a lot of time. Instead, it should end up saving you time. And as you know, the manager loves it when you manage to save time. You will understand how TDD works, how to integrate the important bits of TDD and how to build a high-quality test suite that is a pleasure to maintain. To round things out, you will also learn about Xcode 11’s new test plans feature and how you can use it to make your test suite even better!
Lập trình hướng kiểm thử - Test Driven developmentAnh Lê
This document discusses test driven development (TDD). It begins with an overview of TDD, explaining that TDD is a strong methodology that helps prevent bugs regardless of programming language. It then explains how to implement TDD using the "red/green/refactor" process in incremental baby steps. An example of reversing the last two characters of a string is provided. Benefits of TDD include clean code, preventing bugs, serving as documentation, and helping programmers design better. Common mistakes in TDD are also discussed. The document concludes with questions and answers about TDD.
Using Query Store in Azure PostgreSQL to Understand Query PerformanceGrant Fritchey
Microsoft has added an excellent new extension in PostgreSQL on their Azure Platform. This session, presented at Posette 2024, covers what Query Store is and the types of information you can get out of it.
Hand Rolled Applicative User ValidationCode KataPhilip Schwarz
Could you use a simple piece of Scala validation code (granted, a very simplistic one too!) that you can rewrite, now and again, to refresh your basic understanding of Applicative operators <*>, <*, *>?
The goal is not to write perfect code showcasing validation, but rather, to provide a small, rough-and ready exercise to reinforce your muscle-memory.
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2. TDD Walkthrough - Encryption
Hello and welcome to my TDD Walkthrough!
Today’s exercise is Encryption, taken from
hackerrank.com at the following URL:
https://www.hackerrank.com/challenges/encrypti
on/problem
3. TDD Walkthrough - Encryption
In these TDD Walkthroughs, I assume that my
readers have basic knowledge of test driven
development. I highly suggest having an
understanding of TDD before going through this
walkthrough. The following blog post explains
the cycles of TDD.
http://blog.cleancoder.com/uncle-bob/2014/12/1
7/TheCyclesOfTDD.html
I also assume that my readers have knowledge
of refactoring tools and terminology. If you need
more information, this blog post on the six core
refactorings will provide enough information.
http://arlobelshee.com/the-core-6-refactorings/
4. TDD Walkthrough - Encryption
For this exercise, I have the following already set up:
Chrome browser
Visual Studio Code or your personal IDE
Jasmine testing framework
(see my other blog on setting up: https://www.greatersum.com/tdd-setup-jasmine/)
With the above already set up, let’s get started!
5. TDD Walkthrough - Encryption
This walkthrough starts with an already set up
Jasmine standalone project from my other blog
post.
From there, I will create the file that contains my
tests.
6. TDD Walkthrough - Encryption
There are various conventions for file names out
there. I learned to name all my test files Spec
files. I will name my spec file encryption.spec.js.
7. TDD Walkthrough - Encryption
The spec file needs to be included in the
Jasmine spec runner, so open up the
SpecRunner.html file next.
Look for the comment that says “include spec
files here”, and include the spec file you just
created.
8. TDD Walkthrough - Encryption
We are now ready to write tests. Which tests do
we write? Let’s start a test list.
The problem description on hackerrank.com
includes 3 good examples for our test list.
In situations where you’re not familiar with the
problem, you might be afraid to think of up a
comprehensive list of tests that cover all
situations. It’s ok to make an imperfect test list.
Just have a few tests, enough to get started.
haveaniceday => hae and via ecy
feedthedog => fto ehg ee dd
chillout => clu hlt io
9. TDD Walkthrough - Encryption
Let’s write our first test. First, we create the test
suite:
And then we write the test function:
In our test function, we write what we are
expecting:
10. TDD Walkthrough - Encryption
At this point, you should be able to run your test runner HTML file by opening it in
the browser, and see a failing test.
Failing the test here is good! You haven’t written any production code yet, and
that’s ok. What you did write is a test that will tell you when your code fulfilled a
purpose. It’s not much, but we take one step at a time.
11. TDD Walkthrough - Encryption
Ok, so what does the test runner say?
encrypt is not defined. That makes sense, we
haven’t written anything called encrypt yet.
Let’s go make that function!
12. TDD Walkthrough - Encryption
To keep the code organized well, the tests are
contained in the spec file, in the spec folder.
So then our source code should go in the source
folder!
13. TDD Walkthrough - Encryption
Our new source file will need to be included in
the Spec Runner though, so let’s not forget to do
that.
14. TDD Walkthrough - Encryption
Now back to our source file. The first issue is
that encrypt is not defined, so let’s go define it.
15. TDD Walkthrough - Encryption
You might be tempted to go implement all of the function right now. But bear with
me and take one small step at a time. Let’s focus on the error at hand, and we’ll
tackle each issue as they come up. That way we don’t write extra code for no
reason.
This is, after all, development that is driven by testing. So run the tests again. You
can rerun the tests by refreshing the spec runner page.
16. TDD Walkthrough - Encryption
Ok, different error message. Expected
undefined to be ‘hae and via ecy’.
Well, the solution sounds simple. Make our
function return exactly that string!
17. TDD Walkthrough - Encryption
This solution will make you cringe. It makes me cringe.
But you never write more code than you need. That prevents you from wasting
time on extra code, and it prevents you from writing code that can break other
things in other ways.
Focus on minimal design, and drive your code towards the functionality you want
with tests.
18. TDD Walkthrough - Encryption
Ok, that being said, our current test should pass.
And it does!
Although unnecessary, I take a quick look at our
function to see if there is any refactoring to be
done. Our function is very simple, so no.
We move on to the next test on our list.
19. TDD Walkthrough - Encryption
With the first test case done, let’s do the second
case: “feedthedog” returns “fto ehg ee dd”
Run the tests, and we fail as expected.
20. TDD Walkthrough - Encryption
What’s the fastest way to make that test pass?
Check the input string, and if it is “feedthedog”,
return the encrypted string. This is not the
implementation we want to end up with, but it is
good enough for now.
Do our tests pass? Yes. Now for the fun part:
Refactoring.
21. TDD Walkthrough - Encryption
In the refactoring step, you look for opportunities to improve the code while
passing your current tests, to make sure you didn’t break anything with your
changes.
We can see that we hardcoded our returns and the checking of the input string.
We only handle specific inputs. We need to generalize our implementation. This
will be the start of a large refactoring phase. Many arbitrary design decisions will
be made in the following steps.
22. TDD Walkthrough - Encryption
I usually use one of two approaches to discovering the implementation of a
solution. I might draw out the logic on a whiteboard, or I make small changes in
the code to eventually approach the implementation solution. Drawing out the
solution on a whiteboard makes it easier to visualize the solution. But you still
have to translate that visualization into code, which is not always simple.
I will demonstrate how to make small changes to the code safely and progress
towards the generalized implementation we want. There will be many small steps,
and the slow pace may frustrate you. But going at this slow pace with small steps
will give you confidence that your implementation will work, and you will spend
less time fixing mistakes.
23. TDD Walkthrough - Encryption
The first thing we can do is eliminate the
hardcoded return. I will introduce a variable to
replace it. And as always, rerun tests to make
sure they all pass.
What else do we see here? The result is a
series of strings. I will break up the result into a
bunch of blocks, separated by a space. We are
starting to see a pattern here, but the next step
will make it very obvious.
24. TDD Walkthrough - Encryption
The letters of each block come from the input
string. At very specific indexes too. I can replace
the hardcoded first block with references to
certain characters in the input string. I
experiment by making this change only on the
first block. Did it work? Yes, the tests still pass!
Implement this indexing pattern for the rest of
the blocks, and make sure the tests pass. Now
we feel more comfortable that this function can
handle different strings. But we’re not done yet!
There are many more patterns to implement.
25. TDD Walkthrough - Encryption
There’s a pattern among the indexes too. The
differences in the indexes are 4 and 8. Let’s
make the code express that increment.
So what does this mean? If you look at the
problem description, they tell you that the rows
and columns of the grid they use for the
encryption are based on the length of the string.
There are 3 rows and 4 columns in the grid for
this case. 4 columns seems to match 4 blocks,
and also matches the difference of 4 between
the indexes. The number of columns seems to
be what defines the indexes and the number of
blocks.
26. TDD Walkthrough - Encryption
I want to express the increments as multiples of
the number of columns. So I express the
indexes as multiples of 4.
I am starting to see a consistency among these
blocks. I separate them into their own lines. This
makes it very easy to compare them and
recognize the pattern.
27. TDD Walkthrough - Encryption
I add one little change to the first character of
each block, and now the pattern is very clear.
The index consists of 3 numbers. The first is the
column index, 0 thru 3. The second is the row
index, 0 thru 2. The third is the number of
columns, 4.
All of these numbers are calculated from the
length of the input string, so we will need to
calculate those first before proceeding.
28. TDD Walkthrough - Encryption
According to the problem description, the rows
is the floor function of the square root of the
length. The columns is the ceiling of the square
root of the length.
Now that we have our numbers, we can
implement a for loop for the row index. I make
the change only to the first block as a test, to
make sure it works. As always, whenever we
make changes, run the tests!
29. TDD Walkthrough - Encryption
Two things left to generalize.
Next, I change the 4 into the number of
columns. Tests should still pass. This pattern
should work for all the blocks now, keeping in
mind that the first number, the column index, is
different for each block.
The last thing to generalize here is the column
index. I do make some design decisions here
arbitrarily. Because these blocks are separated
by spaces, my plan is to put these blocks into an
array, and join them together with a space
separator. I will begin to change my code in that
direction.
30. TDD Walkthrough - Encryption
So, my result is an array now instead of a string.
I want to push the blocks of strings into the
array. So I update each block to create a
temporary string (I called it block. Seems
appropriate). This block is pushed onto the
result array. Do this for each block. Then return
the array joined together with a single space.
Make sure the tests still pass.
How did I decide to make a big leap like that?
Just a hunch. There are many ways to do
things, especially in software development.
Experience will teach you when and why to use
some of instead of others. You are welcome to
implement this any other way.
31. TDD Walkthrough - Encryption
Finally, we can generalize the implementation of
the column index, which consolidates most of
this code and removes the duplication.
Implement a for loop for the column index. Put
the code for a block inside the for loop and
change the number that increments to
columnIndex. And now this double for loop
should build the encrypted string for many
scenarios. My idea of testing that would be to
remove the if statement for the case of
“feedthedog”.
32. TDD Walkthrough - Encryption
I remove the if statement, but our test fails!
That’s not good. What happened?
Some investigation will reveal that we tried to
access indexes of the input string that didn’t
exist. Looks like I’ll have to include an if
statement to check if the index is bigger than the
length of the string. Good TDD practice would
be to go back to passing state (this means
putting the if statement back), and then make
the change and run the tests again.
33. TDD Walkthrough - Encryption
I remove the if statement again. This time we
pass the tests.
And that was all one refactoring step! It was a lot
of work. Yes, we could have gone faster. But as
mentioned before, going this slow and taking
steps this small reduces wasted time in fixing
mistakes.I would like to do one more refactoring,
which is to introduce a variable for the string
index, to make it easier to read. As always, run
the tests to make sure they pass.
34. TDD Walkthrough - Encryption
We are nearing the end! We have one last test
to add, which is “chillout => clu hlt io”.
You might think that this test will pass, since our
implementation looks good as is. But it doesn’t!
Why is that?
Turns out, there is a little rule in the encryption
problem description that goes “rows * columns >
L”, where L is the length of the string.
In the “chillout” case, rows is 2, columns is 3, the
grid has an area of 6 characters, and the string
is 8 characters long. That doesn’t work!
c h i
l l o
Where does the u
and the t go?
35. TDD Walkthrough - Encryption
The fastest solution I came up with was to add 1
to the number of rows if the area of the grid was
smaller than the length of the input string. That
satisfies the condition that rows * columns is
always greater than the length of the input
string. That makes the test pass.
And that’s it! This is the completed Encryption
solution. There is room for improvement in this
code in terms of refactoring and structure. I will
let you guys figure out what those improvements
might be.
36. TDD Walkthrough - Encryption
Some final thoughts about this problem.
I did mention before that I made some arbitrary design decisions. The double for
loop was one of them. There are other ways to implement the solution. I
considered trying a for each type of loop, but I wasn’t sure how much effort it
would be to implement. Be sure to use source control on your code, and commit
often. That way, if you make a mistake, you can roll back to an earlier commit and
take a different path without too much hassle.
I hope that this walkthrough helps you understand how to implement test driven
development for your assignments. Good luck!
37. TDD Walkthrough - Encryption
For those who want to look at the source code, I have this walkthrough posted on
github here:
https://github.com/khapeterk/Encryption