This is necessary for mobile apps to do the right thing when only
RemoteUserBackend is enabled, namely, directly redirect to the
third-party SSO auth site as soon as the user enters the server URL
(no need to display a login form, since it'll be useless).
I probably should have just done this in the original implementation;
there's only a small downside in the form of an extra database query
when trying to authenticate a user who doesn't exist.
Structurally, the main change here is replacing the `clean_username`
function, which would get called when one accessed
self.cleaned_data['username'] with code in the main `clean` function.
This is important because only in `clean` do we have access to the
`realm` object.
Since I recently added full test coverage on this form, we know each
of the major cases have a test; the error messages are unchanged.
This deletes the old mock-covered test for this, which was mostly
useless. We have a much less messy test, which we extend to provide
the same test coverage the old one did.
While the result was the same before, this makes it more obvious.
We created this redundant pair of conditionals in a preceding commit,
in order to match the indentation of an `except` block so as to slice
the diffs extra finely as we're refactoring auth code.
This lets us delete some duplicate code, since common_get_active_user
handles an account in the wrong subdomain for us.
Also lets us delete the now-unused common_get_active_user_by_email.
This way, we don't attempt to evaluate whether the user's account is
active (etc.) until after we've checked the backend is enabled. This
won't change the result of actual auth, but feels more readable.
This is a behavior change, though we don't check the value in the
caller regardless. It just seems more logical for us to correctly
report to the caller whether the Google auth itself was valid
unconditionally.
This code path was only required because we had remote_user set as a
positional argument here, and thus we'd be running this auth backend's
code when actually using another auth backend (due to how Django auth
backends are selected based on argument signature).
This require some care to ensure we still provide the same nice error
messages for the case of a user who has an account, just not with this
organization.
Also, we fix the fact that the docstring was (and I think always has
been) at best confusing and perhaps even inaccurate.
Now we have moved the `do_auth` function to `SocialAuthMixin`. Instead
of overriding `do_auth`, derived class is now expected to override
`get_authenticated_user`.
`do_auth` now contains code which is expected by all backends.
Most of these have more to do with authentication in general than with
registering a new account. `create_preregistration_user` could go
either way; we move it to `auth` so we can make the imports go only in
one direction.
Now that every call site of check_subdomain produces its second
argument in exactly the same way, push that shared bit of logic
into a new wrapper for check_subdomain.
Also give that new function a name that says more specifically what
it's checking -- which I think is easier to articulate for this
interface than for that of check_subdomain.