Flask and Werkzeug: Testing a post request with custom headers

open also take *args and **kwargs which used as EnvironBuilder arguments. So you can add just headers argument to your first post request:

with self.app.test_client() as client:
    client.post('/v0/scenes/test/foo',
                data=dict(image=(StringIO('fake image'), 'image.png')),
                headers={'content-md5': 'some hash'});