refactor(oauth): change to approach of registering client in login view

the register method seems to be idempotent, so it's fine to call it like
this. the approach of registering during view import made importing the
module complicated (e.g. when importing from the module for our tests)

benefits/oauth/client.py

@@ -6,9 +6,6 @@
 
 from authlib.integrations.django_client import OAuth
 
-from benefits.core.models import AuthProvider
-
-
 logger = logging.getLogger(__name__)
 
 oauth = OAuth()
@@ -42,23 +39,20 @@ def _authorize_params(scheme):
     return params
 
 
-def register_providers(oauth_registry):
+def register_provider(oauth_registry, provider):
     """
-    Register OAuth clients into the given registry, using configuration from AuthProvider models.
+    Register OAuth clients into the given registry, using configuration from AuthProvider model.
 
     Adapted from https://stackoverflow.com/a/64174413.
     """
-    logger.info("Registering OAuth clients")
-
-    providers = AuthProvider.objects.all()
+    logger.debug(f"Registering OAuth client: {provider.client_name}")
 
-    for provider in providers:
-        logger.debug(f"Registering OAuth client: {provider.client_name}")
+    client = oauth_registry.register(
+        provider.client_name,
+        client_id=provider.client_id,
+        server_metadata_url=_server_metadata_url(provider.authority),
+        client_kwargs=_client_kwargs(provider.scope),
+        authorize_params=_authorize_params(provider.scheme),
+    )
 
-        oauth_registry.register(
-            provider.client_name,
-            client_id=provider.client_id,
-            server_metadata_url=_server_metadata_url(provider.authority),
-            client_kwargs=_client_kwargs(provider.scope),
-            authorize_params=_authorize_params(provider.scheme),
-        )
+    return client

benefits/oauth/views.py

@@ -6,7 +6,7 @@
 
 from benefits.core import session
 from . import analytics, redirects
-from .client import oauth, register_providers
+from .client import oauth, register_provider
 from .middleware import VerifierUsesAuthVerificationSessionRequired
 
 
@@ -20,14 +20,12 @@
 ROUTE_POST_LOGOUT = "oauth:post_logout"
 
 
-register_providers(oauth)
-
-
 @decorator_from_middleware(VerifierUsesAuthVerificationSessionRequired)
 def login(request):
     """View implementing OIDC authorize_redirect."""
     verifier = session.verifier(request)
-    oauth_client = oauth.create_client(verifier.auth_provider.client_name)
+
+    oauth_client = register_provider(oauth, verifier.auth_provider)
 
     if not oauth_client:
         raise Exception(f"oauth_client not registered: {verifier.auth_provider.client_name}")

tests/pytest/oauth/test_client.py

@@ -1,7 +1,7 @@
 import pytest
 
 from benefits.core.models import AuthProvider
-from benefits.oauth.client import _client_kwargs, _server_metadata_url, _authorize_params, register_providers
+from benefits.oauth.client import _client_kwargs, _server_metadata_url, _authorize_params, register_provider
 
 
 def test_client_kwargs():
@@ -39,33 +39,21 @@ def test_authorize_params_no_scheme():
 
 
 @pytest.mark.django_db
-def test_register_providers(mocker, mocked_oauth_registry):
-    mock_providers = []
-
-    for i in range(3):
-        p = mocker.Mock(spec=AuthProvider)
-        p.client_name = f"client_name_{i}"
-        p.client_id = f"client_id_{i}"
-        mock_providers.append(p)
-
-    mocked_client_provider = mocker.patch("benefits.oauth.client.AuthProvider")
-    mocked_client_provider.objects.all.return_value = mock_providers
+def test_register_provider(mocker, mocked_oauth_registry):
+    mocked_client_provider = mocker.Mock(spec=AuthProvider)
+    mocked_client_provider.client_name = "client_name_1"
+    mocked_client_provider.client_id = "client_id_1"
 
     mocker.patch("benefits.oauth.client._client_kwargs", return_value={"client": "kwargs"})
     mocker.patch("benefits.oauth.client._server_metadata_url", return_value="https://metadata.url")
     mocker.patch("benefits.oauth.client._authorize_params", return_value={"scheme": "test_scheme"})
 
-    register_providers(mocked_oauth_registry)
-
-    mocked_client_provider.objects.all.assert_called_once()
-
-    for provider in mock_providers:
-        i = mock_providers.index(provider)
+    register_provider(mocked_oauth_registry, mocked_client_provider)
 
-        mocked_oauth_registry.register.assert_any_call(
-            f"client_name_{i}",
-            client_id=f"client_id_{i}",
-            server_metadata_url="https://metadata.url",
-            client_kwargs={"client": "kwargs"},
-            authorize_params={"scheme": "test_scheme"},
-        )
+    mocked_oauth_registry.register.assert_any_call(
+        "client_name_1",
+        client_id="client_id_1",
+        server_metadata_url="https://metadata.url",
+        client_kwargs={"client": "kwargs"},
+        authorize_params={"scheme": "test_scheme"},
+    )