test: add endpoint registration verification tests

Add comprehensive tests to verify critical API endpoints are registered,
including the /api/process-url endpoint. These tests will prevent future
regressions where endpoints might not be properly registered in the app.

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

tests/test_endpoint_registration.py

@@ -0,0 +1,64 @@
+"""
+Tests to verify that all critical API endpoints are properly registered.
+
+This test module serves as a regression prevention mechanism to ensure
+that endpoints remain accessible after code refactoring or reorganization.
+"""
+
+import pytest
+
+
+@pytest.mark.unit
+class TestEndpointRegistration:
+    """Verify that critical API endpoints are registered in the FastAPI app"""
+
+    def test_process_url_endpoint_exists(self, client):
+        """Verify that /api/process-url endpoint is registered and accessible"""
+        # Make a request to the endpoint - it should not return 404
+        response = client.post(
+            "/api/process-url",
+            json={"url": "https://example.com/test.pdf"}
+        )
+        
+        # The endpoint exists if we don't get a 404
+        # We may get other errors (401, 400, 500, etc.) due to validation or missing mocks,
+        # but 404 specifically means the endpoint is not registered
+        assert response.status_code != 404, (
+            f"Endpoint /api/process-url returned 404 (not found). "
+            f"This indicates the router is not properly registered in the application. "
+            f"Verify that url_upload_router is included in app/api/__init__.py"
+        )
+
+    def test_process_url_endpoint_accepts_post(self, client):
+        """Verify that /api/process-url accepts POST requests"""
+        # Try POST request
+        response = client.post(
+            "/api/process-url",
+            json={"url": "https://example.com/test.pdf"}
+        )
+        
+        # Should not return 405 (Method Not Allowed)
+        assert response.status_code != 405, (
+            f"Endpoint /api/process-url returned 405 (Method Not Allowed) for POST. "
+            f"Verify the endpoint is decorated with @router.post()"
+        )
+
+    def test_api_router_included_in_app(self, client):
+        """Verify that the main API router is included in the FastAPI app"""
+        # Test a few known API endpoints to ensure the /api prefix works
+        endpoints_to_check = [
+            ("/api/process-url", "post"),
+            ("/api/diagnostic/settings", "get"),
+        ]
+        
+        for endpoint, method in endpoints_to_check:
+            if method == "get":
+                response = client.get(endpoint)
+            else:
+                response = client.post(endpoint, json={"url": "https://example.com/test.pdf"})
+            
+            # None of these should return 404
+            assert response.status_code != 404, (
+                f"Endpoint {endpoint} returned 404. "
+                f"Verify that api_router is included in app/main.py with prefix='/api'"
+            )