Unit testing Flask Babel translations

The code you have shown seems to work for me. Please see here complete example based on your description: https://github.com/loomchild/flask_babel_test. When I run ./flask_babel_test_test.py both tests pass.

Could you provide complete source code that allows to reproduce the problem?

Currently I can imagine the following solutions (both of them are present in commented-out sections in the example code linked above):

1. There is some caching involved - try to execute flask.ext.babel.refresh() after updating default locale during the test and see if it helps.

2. If you retrieve browser language automatically from Accept-Language HTTP header using localeselector, for example like this:

   @babel.localeselectordef get_locale():    translations = [str(translation) for translation in babel.list_translations()]    return request.accept_languages.best_match(translations)

   Then instead of modifying app config during the test, specify a header:

   rv = app.test_client().get('/', headers=[("Accept-Language", "pt_BR")])

3. Flask-Babel is not able to find the translations directory during testing - try moving your test Python script or translations directory and see if it helps. I don't know how to customize the location of this directory in Flask-Babel, perhaps creating a symlink or running test from project root directory can help.