Black box testing involves testing a system without knowledge of its internal workings by examining its behaviors and outputs based on given inputs. The document discusses various black box testing techniques including equivalence partitioning, boundary value analysis, cause-effect graphing, and syntax-driven testing. It also describes how black box testing is useful for finding incorrect or missing functions, interface errors, and other types of defects.

1. Black Box Testing

2.  Only input & output functionality are visible.
 Inputs are given and outputs are compared against specification.
Features:
 Correct outputs from inputs properly.
 Test cases are designed from user requirements.
 Test planning can begin early in the software process.
 Looking at the program from an external point of view.

4. Black Box Testing
Input Test Data I
System
output Test Results O
Inputs causing
anomalous
behavior
Outputs which
reveal the
presence of
defects

5. Black Box Testing is a “Expert” in
Finding
 Incorrect or missing functions.
 Interface errors
 Behavior or performance errors.
 Initialization and termination errors.
 Errors in data structures
 External database errors.

6. Graph Based Testing Methods
 Each and every application is build up of some objects. All such objects are
identified and graph is prepared. From this object graph each object
relationship is identified and test cases written accordingly to discover the
errors.

7. Sample Graph Notation
Directed Link
Object 1 Object 2
Object 3
•Nodes are represented as circles.
•Links between nodes are categorized as:
•Directed Link (one direction)
•Bidirectional or Undirected or Symmetric Link: both
directions.
•Parceled links: different relationships established between
nodes.

8. Error Guessing Testing Methods
 This is purely based on previous experience and judgment of tester. Error
Guessing is the art of guessing where errors can be hidden. For this technique
there are no specific tools, writing the test cases that cover all the
application paths.

9. Methods of Black box Testing

10. 1. Equivalence Partitioning
 Equivalence Partitioning is a software test design technique that involves
dividing input values into valid and invalid partitions and selecting
representative values from each partition as test data.

11. 2. Boundary Value Analysis (BVA)
 Boundary Value Analysis is a software test design technique that involves
determination of boundaries for input values and selecting values that are
at the boundaries and just inside/outside of the boundaries as test data.

12. 3. Cause Effect Graphing
 Cause Effect Graphing is a software test design technique that involves
identifying the cases (input conditions) and effects (output conditions),
producing a Cause-Effect Graph, and generating test cases accordingly.

13. 4. Orthogonal Array Testing
 Used to finding errors associated with region faults.
 number of inputs to the system is relatively small, but too large to allow
for exhaustive testing of every possible input to the systems.
 It provides good test coverage with test cases.

14. 5. Syntax Driven Testing
 Very good methodology for compliers and parsers.
 Use BNF notation.
 Described by grammar.
 Grammar for simple arithmetic:
(exp)::=(exp)+(term)|(exp)-(term)|(term)
(term)::=(term)*(factor)|(term)-(factor)|(factor)
(factor)::=(identifier)|(<expression>)
(id)::=|a|b|c|d|e………|z

15. 6. Decision Table-Based Testing
 A decision table is a good way to deal with combinations of things (e.g.
inputs). This technique is sometimes also referred to as a ’cause-effect’
table. The reason for this is that there is an associated logic diagramming
technique called ’cause-effect graphing’ which was sometimes used to help
derive the decision table

16. Empty decision table:
Conditions Rule 1 Rule 2 Rule 3 Rule 4
Repayment amount has
been entered:
Term of loan has been
Entered:

17. 7. Cause and Effect Graphs in
Functional Testing
 Represents relationship between input and output
 Input  cause
 Output  effect.
Ex: ATM Banking Transaction System

18. Causes:
C1: Command is credit
C2: Command is Debit
C3: Account Number is valid.
C4: Transaction amount is Valid.
Effects:
E1: Print “Invalid command”
E2: Print “invalid account number”
E3: Print “debit amount not valid”
E4: debit account
E5: credit account.

19. Types processing modes
 And  effect occurs of all the inputs are true.
 Or  Effect occurs if at least one input is true
 Negation : effect occurs if input are false.

20. C2
C3
C4
E3
and
Used to reduce the test case
count
C1 C2 C3
C4
Don’t
care
condition
True false