Test Reliability

This skill is guidance, not a script. Make correctness depend on controlled conditions, not scheduling luck. A flaky test can expose a product defect or a broken fixture; distinguish them before adding compensation.

When not to use

• Designing or reviewing a failure path in production code. Use error-handling.
• Writing the first test for a behavior with a clear interface. Use tdd.

Inputs and authorization

• Required: the test, fixture, or failing run in scope, and the real execution topology it runs under.
• Authorization: review and diagnosis alone do not authorize repairs or a redesign of the whole suite.

Method

Own the resource

Inspect the actual overlap: tests in one process, separate workers, independent commands, and jobs sharing a host. Process isolation does not isolate ports, fixed paths, databases, or surviving children.