Clean up translations for mocked integrations inbetween tests (#138732)

* Clean up translations for mocked integrations inbetween tests

* Adjust code, add test

* Fix docstring

* Improve cleanup, add test

* Fix test

tests/conftest.py

@@ -11,6 +11,7 @@ import gc
 import itertools
 import logging
 import os
+import pathlib
 import reprlib
 from shutil import rmtree
 import sqlite3
@@ -49,7 +50,7 @@ from . import patch_recorder
 # Setup patching of dt_util time functions before any other Home Assistant imports
 from . import patch_time  # noqa: F401, isort:skip
 
-from homeassistant import core as ha, loader, runner
+from homeassistant import components, core as ha, loader, runner
 from homeassistant.auth.const import GROUP_ID_ADMIN, GROUP_ID_READ_ONLY
 from homeassistant.auth.models import Credentials
 from homeassistant.auth.providers import homeassistant
@@ -85,6 +86,7 @@ from homeassistant.helpers import (
     issue_registry as ir,
     label_registry as lr,
     recorder as recorder_helper,
+    translation as translation_helper,
 )
 from homeassistant.helpers.dispatcher import async_dispatcher_send
 from homeassistant.helpers.translation import _TranslationsCacheData
@@ -1234,9 +1236,8 @@ def mock_get_source_ip() -> Generator[_patch]:
 def translations_once() -> Generator[_patch]:
     """Only load translations once per session.
 
-    Warning: having this as a session fixture can cause issues with tests that
-    create mock integrations, overriding the real integration translations
-    with empty ones. Translations should be reset after such tests (see #131628)
+    Note: To avoid issues with tests that mock integrations, translations for
+    mocked integrations are cleaned up by the evict_faked_translations fixture.
     """
     cache = _TranslationsCacheData({}, {})
     patcher = patch(
@@ -1250,6 +1251,30 @@ def translations_once() -> Generator[_patch]:
         patcher.stop()
 
 
+@pytest.fixture(autouse=True, scope="module")
+def evict_faked_translations(translations_once) -> Generator[_patch]:
+    """Clear translations for mocked integrations from the cache after each module."""
+    real_component_strings = translation_helper._async_get_component_strings
+    with patch(
+        "homeassistant.helpers.translation._async_get_component_strings",
+        wraps=real_component_strings,
+    ) as mock_component_strings:
+        yield
+    cache: _TranslationsCacheData = translations_once.kwargs["return_value"]
+    component_paths = components.__path__
+
+    for call in mock_component_strings.mock_calls:
+        integrations: dict[str, loader.Integration] = call.args[3]
+        for domain, integration in integrations.items():
+            if any(
+                pathlib.Path(f"{component_path}/{domain}") == integration.file_path
+                for component_path in component_paths
+            ):
+                continue
+            for loaded_for_lang in cache.loaded.values():
+                loaded_for_lang.discard(domain)
+
+
 @pytest.fixture
 def disable_translations_once(
     translations_once: _patch,