How can I run tests with a specific language?

[xrad]

I have configured my entities properly with _attr_has_entity_name = True, a translation_key and populated my translation jsons. This works, as my entity.name yield the correct translation from the en.json. Now I want to verify the de.json, but simply setting hass.config.language = "de" does not work.

What is the recommended way to do this?

[xrad]

I now do this:

    for lang in [ "en", "de" ]:
        translations = await async_get_translations(hass, lang, "entity", [DOMAIN])

I can then filter and the translations against other sets such as all sensor keys.

But I would still be interested if it is possible to launch a mock hass with a different default language.