# Ha Test Harness > Testing patterns for Home Assistant custom components—coordinator and entity unit tests, register map coverage, write-path tests, and unique_id/device stability checks. Use when this capability is needed. - Skill: `tomevault-io/ha-test-harness` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/ha-test-harness` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/ha-test-harness/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Integrations & APIs - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/ha-test-harness --- # 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. ## References - [references/coordinator-tests.md](references/coordinator-tests.md) - [references/entity-tests.md](references/entity-tests.md) - [references/write-path-tests.md](references/write-path-tests.md) - [references/registry-stability.md](references/registry-stability.md) --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/plebann) — claim your Tome and manage your conversions.