Glossary · Verification and validation
Test coverage
In verification and validation, test coverage is the extent to which requirements, functions, states, interfaces, and fault conditions are exercised by tests. It shows what has been tested and, just as important, what has not.
- Verification
- Systems engineering
In one sentence
Test coverage measures how much of the requirements, states, interfaces and fault conditions the tests actually exercise.
Example
A coverage matrix for a robot cell shows that every safety function was tested in automatic mode, but that the collaborative mode and the loss of the fieldbus connection were never tested.
How it applies
- Verification: Build coverage from trace links between requirements and tests. A requirement without a linked test is an open gap.
- Integrated systems: Coverage of single functions is not enough. Include operating modes, state transitions, interfaces between machines and fault conditions such as communication loss.
- Evidence: Report coverage honestly, including untested items and the reason (tested by analysis, not applicable, deferred). Auditors look for this.
- Software: For safety software, code coverage measures (statements, branches) are one part of test coverage. Requirement coverage is the other and matters more for the safety claim.
Test coverage vs. diagnostic coverage
Test coverage describes how thoroughly a system has been tested before or during validation. Diagnostic coverage describes how many dangerous failures the system detects by itself in operation.