Clean up authentication helper functions

* Remove unused function and its test
* Refactor existing functions

changelog.d/+oauth2.removed.md

@@ -0,0 +1,3 @@
+As part of refactoring some authentication utility functions the function
+`get_psa_authentication_names()` has been removed as it wasn't used anywhere in
+Argus proper.

src/argus/auth/utils.py

@@ -1,31 +1,45 @@
 from django.conf import settings
-from django.contrib.auth.backends import ModelBackend
+from django.contrib.auth.backends import ModelBackend, RemoteUserBackend
 from django.utils.module_loading import import_string
 
 from rest_framework.reverse import reverse
-from social_core.backends.base import BaseAuth
+
 from social_core.backends.oauth import BaseOAuth2
 
 
+_all__ = [
+    "get_authentication_backend_classes",
+    "has_model_backend",
+    "has_remote_user_backend",
+    "get_psa_authentication_backends",
+    "get_authentication_backend_name_and_type",
+]
+
+
 def get_authentication_backend_classes():
     backend_dotted_paths = getattr(settings, "AUTHENTICATION_BACKENDS")
     backends = [import_string(path) for path in backend_dotted_paths]
     return backends
 
 
-def get_psa_authentication_names(backends=None):
+def has_model_backend(backends):
+    return ModelBackend in backends
+
+
+def has_remote_user_backend(backends):
+    return RemoteUserBackend in backends
+
+
+def get_psa_authentication_backends(backends=None):
     backends = backends if backends else get_authentication_backend_classes()
-    psa_backends = set()
-    for backend in backends:
-        if issubclass(backend, BaseAuth):
-            psa_backends.add(backend.name)
-    return sorted(psa_backends)
+    return [backend for backend in backends if issubclass(backend, BaseOAuth2)]
 
 
 def get_authentication_backend_name_and_type(request):
+    # Needed for SPA /login-methods/ API endpoint
     backends = get_authentication_backend_classes()
     data = []
-    if ModelBackend in backends:
+    if has_model_backend(backends):
         data.append(
             {
                 "type": "username_password",
@@ -40,8 +54,7 @@ def get_authentication_backend_name_and_type(request):
             "url": reverse("social:begin", kwargs={"backend": backend.name}, request=request),
             "name": backend.name,
         }
-        for backend in backends
-        if issubclass(backend, BaseOAuth2)
+        for backend in get_psa_authentication_backends(backends)
     )
 
     return data

tests/auth/test_utils.py

@@ -3,7 +3,7 @@
 from django.contrib.auth.backends import ModelBackend
 from django.test import TestCase
 
-from argus.auth.utils import get_authentication_backend_name_and_type, get_psa_authentication_names
+from argus.auth.utils import get_authentication_backend_name_and_type
 from argus.dataporten.social import DataportenFeideOAuth2
 
 
@@ -33,8 +33,3 @@ def test_get_authentication_backend_name_and_type_returns_feide_login(
                 "name": "dataporten_feide",
             }
         ]
-
-    @patch("argus.auth.utils.get_authentication_backend_classes")
-    def test_get_psa_authentication_names_returns_feide_name(self, mock_get_authentication_backend_classes):
-        mock_get_authentication_backend_classes.return_value = [DataportenFeideOAuth2]
-        assert get_psa_authentication_names() == ["dataporten_feide"]