core: add tests for non-applicable flows with flow manager

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

authentik/core/tests/test_source_flow_manager.py

@@ -6,8 +6,12 @@ from guardian.utils import get_anonymous_user
 
 from authentik.core.models import SourceUserMatchingModes, User
 from authentik.core.sources.flow_manager import Action
+from authentik.flows.models import Flow, FlowDesignation
 from authentik.lib.generators import generate_id
 from authentik.lib.tests.utils import get_request
+from authentik.policies.denied import AccessDeniedResponse
+from authentik.policies.expression.models import ExpressionPolicy
+from authentik.policies.models import PolicyBinding
 from authentik.sources.oauth.models import OAuthSource, UserOAuthSourceConnection
 from authentik.sources.oauth.views.callback import OAuthSourceFlowManager
 
@@ -17,7 +21,7 @@ class TestSourceFlowManager(TestCase):
 
     def setUp(self) -> None:
         super().setUp()
-        self.source = OAuthSource.objects.create(name="test")
+        self.source: OAuthSource = OAuthSource.objects.create(name="test")
         self.factory = RequestFactory()
         self.identifier = generate_id()
 
@@ -143,3 +147,34 @@ class TestSourceFlowManager(TestCase):
         action, _ = flow_manager.get_action()
         self.assertEqual(action, Action.ENROLL)
         flow_manager.get_flow()
+
+    def test_error_non_applicable_flow(self):
+        """Test error handling when a source selected flow is non-applicable due to a policy"""
+        self.source.user_matching_mode = SourceUserMatchingModes.USERNAME_LINK
+
+        flow = Flow.objects.create(
+            name="test", slug="test", title="test", designation=FlowDesignation.ENROLLMENT
+        )
+        policy = ExpressionPolicy.objects.create(
+            name="false", expression="""ak_message("foo");return False"""
+        )
+        PolicyBinding.objects.create(
+            policy=policy,
+            target=flow,
+            order=0,
+        )
+        self.source.enrollment_flow = flow
+        self.source.save()
+
+        flow_manager = OAuthSourceFlowManager(
+            self.source,
+            get_request("/", user=AnonymousUser()),
+            self.identifier,
+            {"username": "foo"},
+        )
+        action, _ = flow_manager.get_action()
+        self.assertEqual(action, Action.ENROLL)
+        response = flow_manager.get_flow()
+        self.assertIsInstance(response, AccessDeniedResponse)
+        # pylint: disable=no-member
+        self.assertEqual(response.error_message, "foo")