Update the common fixture to trigger a new one which will started an exposer thread

akita-flask-article-snippet-02-fixtures.diff

@pytest.fixture
- def test_client():
+ def test_client(exposer_thread):
    configure_app(flask_app, config_name=Environments.TESTS)
    # I use this a lot for custom Test client classes to inject custom things
    my_project.app.test_client_class = CustomApiTestClient
    client = my_project.app.test_client
    yield client