fix: adds user friendly flas message

test/mv_web/controllers/auth_controller_test.exs

@@ -248,4 +248,48 @@ defmodule MvWeb.AuthControllerTest do
 
     assert to =~ "/auth/user/password/sign_in_with_token"
   end
+
+  # OIDC/Rauthy error handling tests
+  describe "handle_rauthy_failure/2" do
+    test "Assent.ServerUnreachableError redirects to sign-in with error flash", %{
+      conn: authenticated_conn
+    } do
+      conn = build_unauthenticated_conn(authenticated_conn)
+      # Create a mock Assent.ServerUnreachableError struct
+      error = %Assent.ServerUnreachableError{request_url: "https://auth.example.com/callback?token=secret123"}
+
+      conn = MvWeb.AuthController.failure(conn, {:rauthy, :callback}, error)
+
+      assert redirected_to(conn) == ~p"/sign-in"
+      assert get_flash(conn, :error) == "The authentication server is currently unavailable. Please try again later."
+    end
+
+    test "Assent.InvalidResponseError redirects to sign-in with error flash", %{
+      conn: authenticated_conn
+    } do
+      conn = build_unauthenticated_conn(authenticated_conn)
+      # Create a mock Assent.InvalidResponseError struct
+      error = %Assent.InvalidResponseError{
+        response: %{status_code: 400, body: "invalid_request"},
+        request_url: "https://auth.example.com/callback"
+      }
+
+      conn = MvWeb.AuthController.failure(conn, {:rauthy, :callback}, error)
+
+      assert redirected_to(conn) == ~p"/sign-in"
+      assert get_flash(conn, :error) == "Authentication configuration error. Please contact the administrator."
+    end
+
+    test "unknown reason triggers catch-all and redirects to sign-in with error flash", %{
+      conn: authenticated_conn
+    } do
+      conn = build_unauthenticated_conn(authenticated_conn)
+      unknown_reason = :oops
+
+      conn = MvWeb.AuthController.failure(conn, {:rauthy, :callback}, unknown_reason)
+
+      assert redirected_to(conn) == ~p"/sign-in"
+      assert get_flash(conn, :error) == "Unable to authenticate with OIDC. Please try again."
+    end
+  end
 end