Software testability means how easily a computer program can be tested. There are certain metrics that can be used to measure testability. Sometimes testability is used to means how adequately a particular set of tests will cover the product. The checklist that follows provides a set of characteristics that lead to testable software. by using the following attributes engineer can develop a software configuration i.e., programs data and documents that is easy to test.

Operability: The better it works, the more efficiently it can be tested.
•    The system has few bugs (bugs add analysis and reporting overhead to the test process).
•    No bugs block the execution of tests.
•    The product evolves in functional stages (allow simultaneous development and testing).

Operability: “What you see is what you test”
•    Distinct output is generated for each input.
•    Past system states and variables are visible or quartile
•    All factors affecting the output are visible.
•    Incorrect output is easily identified.
•    Internal errors are automatically detected through self-testing mechanisms.
•    Internal errors are automatically reported.
•    Source code is accessible.

Controllability: “The better we can control the software, the more the testing can be automated and optimized.”
•    All possible outputs can be generated through some combination of input.
•    All code is executable through some combination of input.
•    Software and hardware states and variables can be controlled directly by the test engineer.
•    Input and output formats are consistent and structured.
•    Tests can be conveniently specified, and reproduced.

Decomposability: “By controlling the scope of testing, we can more quickly isolate problems and perform smarter retesting.”
•    The software system is built from independent modules.
•    Software modules can be tested independently.

Simplicity : “The less there is to test, the more quickly we can test it.”
•    Functional simplicity (e.g., the features set is the minimum necessary to meet requirements.
•    Strctural simplicity (e.g., architecture is modularized to limit the propagation of faults).
•    Code simplicity (e.g., a coding standard is adopted for ease of inspection and maintenance).

Stability: “The fewer the changes, the fewer the disruptions to testing.”
•    Changes to the software are infrequent.
•    Changes to the software are controlled.
•    Changes to the software do not invalidate existing tests.

 Understandability: “The more information we have, the smarter we will test.”
•    The design is well understood.
•    Dependencies between internal, external and shared components are well understood.
•    Changes to the design are communicated.
•    Technical documentation is instantly accessible.
•    Technical documentation is well organized.
•    Technical documentation is specific and detailed.
•    Technical documentation is accurate.

For more help in Software Testability click the button below to submit your homework assignment