Testing Techniques (Black-box, White-box, Grey-box)

Definition: Black-box testing, also known as functional testing, is a testing technique that evaluates the functionality of an application without knowing the internal workings of the system.
Testers focus on testing the input and output of the software, without knowing the structure, code, or architecture of the software.

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Characteristics of black-box testing:

Focus on User Perspective: This technique mainly focuses on the inputs and outputs of the software from the user’s perspective.
Tests Functionality: It tests the functionality of the software without considering how the software is designed and implemented.
Independent of Programming Language: The testers don’t need to know the programming language or internal code of the software to perform black-box testing.

Equivalence Partitioning: Divides input data into partitions, and one representative value is chosen from each partition for testing.
Boundary Value Analysis: Focuses on testing the boundary values of input ranges, usually paying attention to the maximum, minimum, and out-of-range values.
State Transition Testing: Tests the system or software for different states and their transitions to ensure the correct behavior based on those transitions.

Definition: White-box testing, also known as structural or glass box testing, is a testing technique that evaluates the internal workings of a software system.
Testers have access to the source code and internal structure of the software to design test cases.

Based on Internal Code: This technique focuses on the internal structure, code, and design of the software.
Tests the Internal Logic: It checks the internal logic of the software to identify any errors, and verifies the execution paths in the code.
Dependent on Programming Language: The testers need to have knowledge of the programming language and internal code of the software to perform white-box testing.

Statement Coverage: This metric calculates the percentage of statements in the code that are executed during testing, aiming to ensure all code lines are covered by test cases.
Branch Coverage: This metric calculates the percentage of branches (decisions) in the code that are executed during testing, aiming to ensure all decision points in the code are covered by test cases.

Definition: Grey-box testing is a combination of both black-box and white-box testing techniques. Testers have partial knowledge of the internal workings of the software.
They may have access to some parts of the code or design, but not all.

Combines Black-box and White-box: It combines the advantages of both black-box and white-box testing techniques.
Requires Partial Access: Testers need partial access to the internal structure or code of the software.
Tests Based on the Available Knowledge: Testers use the knowledge they have about the internal workings of the software to design test cases.

Examples