assertRedirects assume HTTP is always the used protocol

[rafspiny]

The function in object assume HTTP is the only scheme.
If the PREFERRED_URL_SCHEME has been set to HTTPS it will not pick up the changes, resulting in false positives during testing.

It is true that you can pass an absolute URL, bypassing the problem. Nevertheless, I am wondering if it would be better to have this function to comply with the PREFERRED_URL_SCHEME specified in Flask.

Code here

Suggested change:

expected_location = urljoin("%s://%s" % (self.app.config.get('PREFERRED_URL_SCHEME'), server_name), location)