auth-node: move parseWebPessageResponse to test util + fix error value handling

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

plugins/auth-node/src/flow/__testUtils__/parseWebMessageResponse.ts

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2023 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { WebMessageResponse } from '../sendWebMessageResponse';
+
+export function parseWebMessageResponse(text: string): {
+  response: WebMessageResponse;
+  origin: string;
+} {
+  const [response, origin] = text.matchAll(/decodeURIComponent\('(.+?)'\)/g);
+  return {
+    response: JSON.parse(decodeURIComponent(response[1])),
+    origin: decodeURIComponent(origin[1]),
+  };
+}

plugins/auth-node/src/flow/sendWebMessageResponse.test.ts

@@ -20,6 +20,7 @@ import {
   sendWebMessageResponse,
   type WebMessageResponse,
 } from './sendWebMessageResponse';
+import { parseWebMessageResponse } from './__testUtils__/parseWebMessageResponse';
 
 describe('oauth helpers', () => {
   describe('safelyEncodeURIComponent', () => {
@@ -78,7 +79,12 @@ describe('oauth helpers', () => {
         type: 'authorization_response',
         error: new Error('Unknown error occurred'),
       };
-      const encoded = safelyEncodeURIComponent(JSON.stringify(data));
+      const encoded = safelyEncodeURIComponent(
+        JSON.stringify({
+          type: 'authorization_response',
+          error: { name: 'Error', message: 'Unknown error occurred' },
+        }),
+      );
 
       sendWebMessageResponse(mockResponse, appOrigin, data);
       expect(mockResponse.setHeader).toHaveBeenCalledTimes(3);
@@ -122,20 +128,29 @@ describe('oauth helpers', () => {
         },
       };
       sendWebMessageResponse(mockResponse, appOrigin, data);
-      expect(responseBody.match(/.postMessage\(/g)).toHaveLength(2);
-      expect(
-        responseBody.match(/.postMessage\([a-zA-z.()]*, \'\*\'\)/g),
-      ).toHaveLength(1);
+      expect(parseWebMessageResponse(responseBody).response).toEqual({
+        type: 'authorization_response',
+        response: {
+          providerInfo: expect.any(Object),
+          profile: {
+            email: 'foo@bar.com',
+          },
+          backstageIdentity: expect.any(Object),
+        },
+      });
 
       const errData: WebMessageResponse = {
         type: 'authorization_response',
         error: new Error('Unknown error occurred'),
       };
       sendWebMessageResponse(mockResponse, appOrigin, errData);
-      expect(responseBody.match(/.postMessage\(/g)).toHaveLength(2);
-      expect(
-        responseBody.match(/.postMessage\([a-zA-z.()]*, \'\*\'\)/g),
-      ).toHaveLength(1);
+      expect(parseWebMessageResponse(responseBody).response).toEqual({
+        type: 'authorization_response',
+        error: {
+          name: 'Error',
+          message: 'Unknown error occurred',
+        },
+      });
     });
 
     it('handles single quotes and unicode chars safely', () => {

plugins/auth-node/src/flow/sendWebMessageResponse.ts

@@ -17,6 +17,7 @@
 import { Response } from 'express';
 import crypto from 'crypto';
 import { ClientAuthResponse } from '../types';
+import { serializeError } from '@backstage/errors';
 
 /**
  * Payload sent as a post message after the auth request is complete.
@@ -47,7 +48,12 @@ export function sendWebMessageResponse(
   appOrigin: string,
   response: WebMessageResponse,
 ): void {
-  const jsonData = JSON.stringify(response);
+  const jsonData = JSON.stringify(response, (_, value) => {
+    if (value instanceof Error) {
+      return serializeError(value);
+    }
+    return value;
+  });
   const base64Data = safelyEncodeURIComponent(jsonData);
   const base64Origin = safelyEncodeURIComponent(appOrigin);
 

plugins/auth-node/src/oauth/createOAuthRouteHandlers.test.ts

@@ -24,8 +24,8 @@ import { createOAuthRouteHandlers } from './createOAuthRouteHandlers';
 import { OAuthAuthenticator } from './types';
 import { errorHandler } from '@backstage/backend-common';
 import { encodeOAuthState, OAuthState } from './state';
-import { WebMessageResponse } from '../flow';
 import { PassportProfile } from '../passport';
+import { parseWebMessageResponse } from '../flow/__testUtils__/parseWebMessageResponse';
 
 const mockAuthenticator: jest.Mocked<OAuthAuthenticator<unknown, unknown>> = {
   initialize: jest.fn(_r => ({ ctx: 'authenticator' })),
@@ -109,17 +109,6 @@ function getGrantedScopesCookie(test: SuperAgentTest) {
   });
 }
 
-function parseWebMessageResponse(text: string): {
-  response: WebMessageResponse;
-  origin: string;
-} {
-  const [response, origin] = text.matchAll(/decodeURIComponent\('(.+?)'\)/g);
-  return {
-    response: JSON.parse(decodeURIComponent(response[1])),
-    origin: decodeURIComponent(origin[1]),
-  };
-}
-
 describe('createOAuthRouteHandlers', () => {
   afterEach(() => jest.clearAllMocks());