Testing Strategy

Tests are the only correctness instrument you control at build time: shape the suite to the code, not to a decades-old ratio, and make each test assert behaviour a build either passes or fails. Applies to every test under test/ and integration_test/.

Read the reference for the task at hand:

• references/test-layers.md — per-layer harness, imports, teardown, edge tables (pure core, in-memory Drift, headless Notifier, integration).
• references/property-and-fakes.md — fakes-over-mocks, enum-driven fake state, seeded fuzz, independent oracles, absence-of-a-failure-class tests.
• references/coverage-and-budget.md — file-level floors, the coverage-lies-upward fix, the suite-time budget, and the manual-pass handoff.

Run scripts/check_test_hygiene.sh and scripts/run_tests.sh before a PR.

Golden, RTL, and a11y widget mechanics live in widget-golden-and-a11y-testing; this skill governs everything below the pixel.

Non-negotiable rules