Handle errors during an oauth start stage

Signed-off-by: João Madureira <jpmadureira@gmail.com>

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

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2020 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 { Strategy } from 'passport';
+import { PassportOAuthAuthenticatorHelper } from './PassportOAuthAuthenticatorHelper';
+
+class FailureStrategy extends Strategy {
+  public override authenticate(_: any, __: any) {
+    this.error(new Error('failure'));
+  }
+}
+
+describe('PassportOAuthAuthenticatorHelper', () => {
+  describe('start', () => {
+    it('should gracefully handle errors if unable to start', async () => {
+      const helper = PassportOAuthAuthenticatorHelper.from(new FailureStrategy());
+      await expect(helper.start({} as any, {})).rejects.toThrow(
+        'Authentication failed, failure',
+      );
+    });
+  });
+
+  describe('authenticate', () => {
+    it('should gracefully handle errors if unable to authenticate', async () => {
+      const helper = PassportOAuthAuthenticatorHelper.from(new FailureStrategy());
+      await expect(helper.authenticate({} as any, {})).rejects.toThrow(
+        'Authentication failed, failure',
+      );
+    });
+  });
+});

plugins/auth-node/src/passport/PassportHelpers.ts

@@ -105,8 +105,11 @@ export class PassportHelpers {
      */
     status?: number;
   }> {
-    return new Promise(resolve => {
+    return new Promise((resolve, reject) => {
       const strategy = Object.create(providerStrategy);
+      strategy.error = (error: Error) => {
+        reject(new Error(`Authentication failed, ${error.message ?? ''}`));
+      };
       strategy.redirect = (url: string, status?: number) => {
         resolve({ url, status: status ?? undefined });
       };