Accidents happen. Tests get deleted by accident. The test runner may have bugs.
It is good to have
TestPositiveConfirmation.
It is good to have simple, easily verified, consistency checks for a large test suite.
The
TestInventory pattern is one example of such a consistency check.
An even simpler
TestSuiteConsistencyCheck is to report the number of tests run, passed, failed, etc., in the hope that the human or tool running the test would notice if the number of tests run has changed.
Or, preferably, your test runner /
ContinuousBuild environment can detect when the number of tests have diminished, and alarm the appropriate personnel.
CategoryTesting