fix: expose express middleware, add system-test

README.md

@@ -103,6 +103,64 @@ logger.info('hello winston')
 
 ```
 
+### Using as an express middleware (winston 3.1+)
+
+***NOTE: this feature is experimental. The API may change in a backwards
+incompatible way until this is deemed stable. Please provide us feedback so
+that we can better refine this express integration.***
+
+We provide a middleware that can be used in an express application. Apart from
+being easy to use, this enables some more powerful features of Stackdriver
+Logging: request bundling. Any application logs emitted on behalf of a specific
+request will be shown nested inside the request log as you see in this
+screenshot:
+
+![Request Bundling Example](https://raw.githubusercontent.com/googleapis/nodejs-logging-winston/master/doc/images/request-bundling.png)
+
+This middleware adds a `winston`-style log function to the `request` object.
+You can use this wherever you have access to the `request` object (`req` in the
+sample below). All log entries that are made on behalf of a specific request are
+shown bundled together in the Stackdriver Logging UI.
+
+```javascript
+const lw = require('@google-cloud/logging-winston');
+
+// Import express module and create an http server.
+const express = require('express');
+
+async function main() {
+  const {logger, mw} = await lw.express.middleware();
+  const app = express();
+
+  // Install the logging middleware. This ensures that a Winston-style `log`
+  // function is available on the `request` object. Attach this as one of the
+  // earliest middleware to make sure that the log function is available in all
+  // subsequent middleware and routes.
+  app.use(mw);
+
+  // Setup an http route and a route handler.
+  app.get('/', (req, res) => {
+    // `req.log` can be used as a winston style log method. All logs generated
+    // using `req.log` use the current request context. That is, all logs
+    // corresponding to a specific request will be bundled in the Stackdriver
+    // UI.
+    req.log.info('this is an info log message');
+    res.send('hello world');
+  });
+
+  // `logger` can be used as a global logger, one not correlated to any specific
+  // request.
+  logger.info('bonjour');
+
+  // Start listening on the http server.
+  app.listen(8080, () => {
+    logger.info('http server listening on port 8080');
+  });  
+}
+
+main();
+```
+
 ### Error Reporting
 
 Any `Error` objects you log at severity `error` or higher can automatically be picked up by [Stackdriver Error Reporting][error-reporting] if you have specified a `serviceContext.service` when instantiating a `LoggingWinston` instance:

package.json

@@ -78,18 +78,18 @@
     "eslint-plugin-prettier": "^3.0.0",
     "gts": "^0.9.0",
     "intelli-espower-loader": "^1.0.1",
+    "linkinator": "^1.1.2",
     "mocha": "^6.0.0",
     "post-install-check": "0.0.1",
     "prettier": "^1.13.6",
-    "require-inject": "^1.4.3",
+    "proxyquire": "^2.1.0",
     "source-map-support": "^0.5.6",
     "teeny-request": "^3.6.0",
     "typescript": "^3.0.0",
     "uuid": "^3.3.2",
-    "winston": "^3.1.0",
-    "linkinator": "^1.1.2"
+    "winston": "^3.1.0"
   },
   "peerDependencies": {
-    "winston": "3.x"
+    "winston": ">=3.1.0"
   }
 }

src/common.ts

@@ -13,7 +13,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 import * as util from 'util';
 import * as types from './types/core';
 

src/index.ts

@@ -2,8 +2,12 @@
 import * as TransportStream from 'winston-transport';
 
 import {LOGGING_TRACE_KEY as COMMON_TRACE_KEY, LoggingCommon} from './common';
+import * as express from './middleware/express';
 import * as types from './types/core';
 
+// Export the express middleware as 'express'.
+export {express};
+
 type Callback = (err: Error, apiResponse: {}) => void;
 
 /**

system-test/logging-winston.ts

@@ -21,7 +21,7 @@ import * as types from '../src/types/core';
 
 import {ErrorsApiTransport} from './errors-transport';
 
-const inject = require('require-inject');
+const proxyquire = require('proxyquire');
 
 const winston = require('winston');
 
@@ -109,9 +109,7 @@ describe('LoggingWinston', function() {
     ] as TestData[]);
 
     const LOG_NAME = logName('logging_winston_system_tests');
-    const LoggingWinston = inject('../src/index', {
-                             winston,
-                           }).LoggingWinston;
+    const LoggingWinston = proxyquire('../src/index', {winston}).LoggingWinston;
 
     const logger = winston.createLogger({
       transports: [new LoggingWinston({logName: LOG_NAME})],
@@ -143,9 +141,8 @@ describe('LoggingWinston', function() {
     it('reports errors', async () => {
       const start = Date.now();
       const service = `logging-winston-system-test-winston3-${UUID}`;
-      const LoggingWinston = inject('../src/index', {
-                               winston,
-                             }).LoggingWinston;
+      const LoggingWinston =
+          proxyquire('../src/index', {winston}).LoggingWinston;
 
       const logger = winston.createLogger({
         transports: [new LoggingWinston(