Update testing instructions in AGENTS.md (home-assistant#170657)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Franck Nijhof <git@frenck.dev>
Co-authored-by: frenck <195327+frenck@users.noreply.github.com>

Author: 3 people

.github/copilot-instructions.md

@@ -28,6 +28,8 @@ This repository contains the core of Home Assistant, a Python 3 based home autom
 
 ## Testing
 
+- Use `uv run pytest` to run tests
+- After modifying `strings.json` for an integration, regenerate the English translation file before running tests: `.venv/bin/python3 -m script.translations develop --integration <integration_name>`. Tests load translations from the generated `translations/en.json`, not directly from `strings.json`.
 - When writing or modifying tests, ensure all test function parameters have type annotations.
 - Prefer concrete types (for example, `HomeAssistant`, `MockConfigEntry`, etc.) over `Any`.
 - Prefer `@pytest.mark.usefixtures` over arguments, if the argument is not going to be used.

AGENTS.md

@@ -18,6 +18,8 @@ This repository contains the core of Home Assistant, a Python 3 based home autom
 
 ## Testing
 
+- Use `uv run pytest` to run tests
+- After modifying `strings.json` for an integration, regenerate the English translation file before running tests: `.venv/bin/python3 -m script.translations develop --integration <integration_name>`. Tests load translations from the generated `translations/en.json`, not directly from `strings.json`.
 - When writing or modifying tests, ensure all test function parameters have type annotations.
 - Prefer concrete types (for example, `HomeAssistant`, `MockConfigEntry`, etc.) over `Any`.
 - Prefer `@pytest.mark.usefixtures` over arguments, if the argument is not going to be used.