refactor: move unexpectedHttpErrorLogger to testlab

packages/rest/src/__tests__/acceptance/routing/routing.acceptance.ts

@@ -12,7 +12,12 @@ import {
   ParameterObject,
   ResponseObject,
 } from '@loopback/openapi-v3-types';
-import {Client, createClientForHandler, expect} from '@loopback/testlab';
+import {
+  Client,
+  createClientForHandler,
+  createUnexpectedHttpErrorLogger,
+  expect,
+} from '@loopback/testlab';
 import {
   ControllerClass,
   ControllerInstance,
@@ -28,7 +33,6 @@ import {
   RestServer,
   SequenceActions,
 } from '../../..';
-import {createUnexpectedHttpErrorLogger} from '../../helpers';
 
 /* # Feature: Routing
  * - In order to build REST APIs

packages/rest/src/__tests__/helpers.ts

@@ -8,30 +8,8 @@ import {
   RequestBodyObject,
   SchemaObject,
 } from '@loopback/openapi-v3-types';
-import {IncomingMessage} from 'http';
-import {LogError} from '..';
 import {RestServerConfig, RestServerResolvedConfig} from '../rest.server';
 
-export function createUnexpectedHttpErrorLogger(
-  expectedStatusCode: number = 0,
-): LogError {
-  return function logUnexpectedHttpError(
-    err: Error,
-    statusCode: number,
-    req: IncomingMessage,
-  ) {
-    if (statusCode === expectedStatusCode) return;
-
-    console.error(
-      'Unhandled error in %s %s: %s %s',
-      req.method,
-      req.url,
-      statusCode,
-      err.stack || err,
-    );
-  };
-}
-
 /**
  * Create an OpenAPI request body spec with the given content
  * @param schema The schema object

packages/rest/src/__tests__/integration/http-handler.integration.ts

@@ -7,7 +7,12 @@ import {Context} from '@loopback/context';
 import {anOpenApiSpec, anOperationSpec} from '@loopback/openapi-spec-builder';
 import {ControllerSpec, get} from '@loopback/openapi-v3';
 import {ParameterObject, RequestBodyObject} from '@loopback/openapi-v3-types';
-import {Client, createClientForHandler, expect} from '@loopback/testlab';
+import {
+  Client,
+  createClientForHandler,
+  createUnexpectedHttpErrorLogger,
+  expect,
+} from '@loopback/testlab';
 import * as express from 'express';
 import * as HttpErrors from 'http-errors';
 import {is} from 'type-is';
@@ -30,7 +35,7 @@ import {
   UrlEncodedBodyParser,
   writeResultToResponse,
 } from '../..';
-import {createUnexpectedHttpErrorLogger, aRestServerConfig} from '../helpers';
+import {aRestServerConfig} from '../helpers';
 
 const SequenceActions = RestBindings.SequenceActions;
 

packages/testlab/README.md

@@ -54,6 +54,8 @@ Table of contents:
 - [httpGetAsync](#httpgetasync) - Async wrapper for HTTP GET requests.
 - [httpsGetAsync](#httpsgetasync) - Async wrapper for HTTPS GET requests.
 - [toJSON](#toJSON) - A helper to obtain JSON data representing a given object.
+- [createUnexpectedHttpErrorLogger](#createUnexpectedHttpErrorLogger) - An error
+  logger that only logs errors for unexpected HTTP statuses.
 
 ### `expect`
 
@@ -287,6 +289,46 @@ describe('MyApp', () => {
 });
 ```
 
+### `createUnexpectedHttpErrorLogger`
+
+An error logger that logs the error only when the HTTP status code is not the
+expected HTTP status code. This is useful when writing tests for error
+responses:
+
+- When we don't want any error messages printed to the console when the server
+  responds with the expected error and the test passes.
+
+- When something else goes wrong and the server returns an unexpected error
+  status code, and we do want an error message to be printed to the console so
+  that we have enough information to troubleshoot the failing test.
+
+```ts
+import {createUnexpectedHttpErrorLogger} from '@loopback/testlab';
+import {RestApplication} from '@loopback/rest';
+
+describe('MyApp', () => {
+  it('does not log a known 401 error to console', async () => {
+    const app = new RestApplication();
+    const errorLogger = createUnexpectedHttpErrorLogger(401);
+
+    const spec = {
+      responses: {
+        /*...*/
+      },
+    };
+    function throwUnauthorizedError() {
+      throw new HttpErrors.Unauthorized('Unauthorized!');
+    }
+
+    app.route('get', '/', spec, throwUnauthorizedError);
+
+    // binds the custom error logger
+    app.bind(SequenceActions.LOG_ERROR).to(errorLogger);
+    await app.start();
+  });
+});
+```
+
 ## Related resources
 
 For more info about `supertest`, please refer to

packages/testlab/src/http-error-logger.ts

@@ -0,0 +1,35 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/testlab
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {Request} from 'express';
+import {IncomingMessage} from 'http';
+
+/**
+ * Creates a Logger that logs an Error if the HTTP status code is not expected
+ *
+ * @param expectedStatusCode HTTP status code that is expected
+ */
+export function createUnexpectedHttpErrorLogger(
+  expectedStatusCode?: number,
+): LogError {
+  return function logUnexpectedHttpError(
+    err: Error,
+    statusCode: number,
+    req: IncomingMessage,
+  ) {
+    if (statusCode === expectedStatusCode) return;
+
+    /* istanbul ignore next */
+    console.error(
+      'Unhandled error in %s %s: %s %s',
+      req.method,
+      req.url,
+      statusCode,
+      err.stack || err,
+    );
+  };
+}
+
+type LogError = (err: Error, statusCode: number, request: Request) => void;

packages/testlab/src/index.ts

@@ -3,13 +3,14 @@
 // This file is licensed under the MIT License.
 // License text available at https://opensource.org/licenses/MIT
 
-export * from './expect';
-export * from './sinon';
 export * from './client';
+export * from './expect';
+export * from './http-error-logger';
+export * from './http-server-config';
+export * from './request';
 export * from './shot';
-export * from './validate-api-spec';
-export * from './test-sandbox';
+export * from './sinon';
 export * from './skip-travis';
-export * from './request';
-export * from './http-server-config';
+export * from './test-sandbox';
 export * from './to-json';
+export * from './validate-api-spec';