Buyer guide
Passing tests do not prove the software matches intent.
Tests verify sampled behavior. Coverage tells you which code ran. Neither proves the critical behavior was specified, intended, or safe across the paths that matter.
Often encode current behavior, including wrong behavior.
Can be high while important conditions are not independently exercised.
Failure modes
What tests and coverage usually miss.
No test fails because nobody wrote down the behavior that should have been checked.
Generated tests can mirror generated code instead of challenging the intended behavior.
Line coverage can miss condition independence, state transitions, and interacting inputs.
Docs, product claims, and implementation disagree, but unit tests only reflect the implementation.
A fix for one path changes equivalent behavior elsewhere without a regression artifact.
Customer reviews need reusable evidence, not only test-count dashboards.
CCA response
Proof checks the chain, not just the tests.
- Recover the intended behavior for one critical path.
- Compare requirements, code, tests, documentation, and evidence.
- Use MC/DC or formal artifacts where they clarify condition or property coverage.
- Produce reproducers and patch-verification evidence for confirmed findings.