Testing patterns for Home Assistant custom components—coordinator and entity unit tests, register map coverage, write-path tests, and unique_id/device stability checks.
SKILL.md
HA Test Harness
Use when adding tests for a custom integration.
Quick start
Unit test the coordinator (success, cached fallback, error paths, option changes).
Validate register maps and expected entities (keys, tiers, categories).
Test entity properties (state_class/device_class/units) and translation_key wiring.
Write-path tests: encoding, device_id usage, no immediate refresh contention.
