Testing Discipline

Full rubric: ${CLAUDE_PLUGIN_ROOT}/docs/principles/tests.md. Gate findings cite these as tests/<rule>.

Assert what the caller can see

Return values, persisted state, messages emitted. Not private fields, not internal call counts. A test coupled to implementation fails on every refactor and stays green through real regressions — it costs maintenance and proves nothing.

Mock-invocation assertions are legitimate only when the interaction is the contract: the email must be sent, the card must be charged exactly once.

The name is the specification