id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
34181	The active locale context can leak across tests when using LocaleMiddleware	Raphaël Barrois	nobody	"Django's LocaleMiddleware only activates a translation, but doesn't deactivate it since #5241 / https://github.com/django/django/commit/aa089b106b6cfc9a47cd54a0f9eb44bd44811ed9.

This has an unwanted side-effect in tests:

{{{
class I18NTests(django.test.TestCase):
    def test_lang(self):
       response = self.client.get(""/"", HTTP_LANGUAGE=""fr-FR"")

    def test_unrelated(self):
        # This value returns a string marked for translation
        context = some_helper()
        self.assertEqual(""Hello folks"", str(context[""greeting""]))
}}}

If `test_lang` runs last, the test suite will succeed.
However, if `test_lang` runs before the other, the test suite will fail: the locale context will still be set to `fr` from the execution of `LocaleMiddleware`.

Most project with i18n enabled assume that all tests run under the project's default locale (i.e `LANGUAGE_CODE`), yet running some tests in other languages will fail.

I can think of a few ways to address this:
- **Documentation** Explain that tests should never check the text value of a returned function without setting an explicit translation context (but that's not exactly intuitive for users);
- **Test-side fix** Adjust `django.test.Client` to restore the initial process locale after the request — or add that to the default `TestCase` tear-down;
- **Server-side fix** find a way to deactivate the translation context when it is safe to do so."	Bug	closed	Internationalization	4.1	Normal	duplicate			Unreviewed	0	0	0	0	0	0