[FIXED] Unit testing Flask Babel translations

Issue

I'd like to do some unit tests to check my flask app translations. I have tried this piece of code:

def test_pt_br(self):
    with app.test_request_context():
        app.config['BABEL_DEFAULT_LOCALE'] = 'pt_BR'
        rv = app.test_client().get('/')
        assert 'Execute, melhore' in str(rv.data)

However, it does not work/pass although the app runs fine. What am I doing wrong?

Solution

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.localeselector
   def 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.

(Improvements: From the source code of flask-babel it looks for the translation folder with the following code:

    @property
    def translation_directories(self):
        directories = self.app.config.get(
            'BABEL_TRANSLATION_DIRECTORIES',
            'translations'
        ).split(';')

        for path in directories:
            if os.path.isabs(path):
                yield path
            else:
                yield os.path.join(self.app.root_path, path)

So for the test you can set the app["BABEL_TRANSLATION_DIRECTORIES"] to the an absolute path to have the test always find the translation or use print(app.root_path) to see where it looks for the root path and link the translation there.

Answered By - loomchild