Classification of software tests

The classification presented here can be found in many publications on software testing. The ones I consulted were B. Beizer, "Black-Box Testing" (1995) and R. V. Binder, "Testing Object-Oriented Systems" (2000). To have productive discussions about testing with your colleagues it is important to have a clear common understanding of the following concepts.

Dirty test (fault-directed):
We try to break the software by doing a falsification, i.e. to demonstrate that the software does not meet requirements.

Clean test (conformance-directed):
Doing a validation, i.e. to show that requirements are met.

Unit testing:
Testing classes or other "small" units. Called and calling components are either assumed to work correctly or replaced by stubs or mocks. This tests should execute very fast and are done by the programmer.

Integration testing:
Testing the interaction and consistency of  units A and B which are aggregated in a new component C.
We assume that the components A and B passed already successfully unit and integration testing.
The scope is a subsystem of software and hardware units which are physically dependent or are required to cooperate.


System testing:
Testing system behaviour that can not be done by unit or integration testing. Examples: performance, reliability. It focuses on capabilities that are present only in the entire system.

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Black-box testing after Beizer

Other names for black-box testing are behavioural or functional testing. Black-box testing is based on requirements. The testers usually have knowledge about the internal structure of the system and the implementation. However the tests should not depend on the implementation details. Beizer suggests to use the following testing strategies:

• Control flow testing
• Loop testing
• Data flow testing
• Transaction flow testing
• Domain testing
• Syntax testing
• Finite-state testing