From f9ddc61d070a35e5df82a5a3d700474e7c336176 Mon Sep 17 00:00:00 2001
From: leak4mk0 <leak4mk0@gmail.com>
Date: Fri, 26 Apr 2019 00:02:51 +0900
Subject: [PATCH] feat(connectLogger): add response to context

---
 docs/connect-logger.md           |  20 ++++++
 lib/connect-logger.js            |   3 +
 test/tap/connect-context-test.js | 112 +++++++++++++++++++++++++++++++
 3 files changed, 135 insertions(+)
 create mode 100644 test/tap/connect-context-test.js

diff --git a/docs/connect-logger.md b/docs/connect-logger.md
index 7ab4329..a906805 100644
--- a/docs/connect-logger.md
+++ b/docs/connect-logger.md
@@ -73,6 +73,26 @@ The log4js.connectLogger also supports a nolog option where you can specify a st
 app.use(log4js.connectLogger(logger, { level: 'auto', format: ':method :url', nolog: '\\.gif|\\.jpg$' }));
 ```
 
+The log4js.connectLogger can add a response of express to context if `context` flag is set to `true`.
+Application can use it in layouts or appenders.
+
+In application:
+
+```javascript
+app.use(log4js.connectLogger(logger, { context: true }));
+```
+
+In layout:
+
+```javascript
+log4js.addLayout('customLayout', () => {
+  return (loggingEvent) => {
+    const res = loggingEvent.context.res;
+    return util.format(...loggingEvent.data, res ? `status: ${res.statusCode}` : '');
+  };
+});
+```
+
 ## Example nolog values
 
 | nolog value | Will Not Log | Will Log |
diff --git a/lib/connect-logger.js b/lib/connect-logger.js
index 328ce5b..1cc4de0 100755
--- a/lib/connect-logger.js
+++ b/lib/connect-logger.js
@@ -205,6 +205,7 @@ function matchRules(statusCode, currentLevel, ruleSet) {
    *   - `level`         A log4js levels instance. Supports also 'auto'
    *   - `nolog`         A string or RegExp to exclude target logs
    *   - `statusRules`   A array of rules for setting specific logging levels base on status codes
+   *   - `context`       Whether to add a response of express to the context
    *
    * Tokens:
    *
@@ -274,12 +275,14 @@ module.exports = function getLogger(logger4js, options) {
 
         const combinedTokens = assembleTokens(req, res, options.tokens || []);
 
+        if (options.context) thisLogger.addContext('res', res);
         if (typeof fmt === 'function') {
           const line = fmt(req, res, str => format(str, combinedTokens));
           if (line) thisLogger.log(level, line);
         } else {
           thisLogger.log(level, format(fmt, combinedTokens));
         }
+        if (options.context) thisLogger.removeContext('res');
       });
     }
 
diff --git a/test/tap/connect-context-test.js b/test/tap/connect-context-test.js
new file mode 100644
index 0000000..2b52661
--- /dev/null
+++ b/test/tap/connect-context-test.js
@@ -0,0 +1,112 @@
+'use strict';
+
+const test = require('tap').test;
+const EE = require('events').EventEmitter;
+const levels = require('../../lib/levels');
+
+class MockLogger {
+  constructor() {
+    this.level = levels.TRACE;
+    this.context = {};
+    this.contexts = [];
+  }
+
+  log() {
+    this.contexts.push(Object.assign({}, this.context));
+  }
+
+  isLevelEnabled(level) {
+    return level.isGreaterThanOrEqualTo(this.level);
+  }
+
+  addContext(key, value) {
+    this.context[key] = value;
+  }
+
+  removeContext(key) {
+    delete this.context[key];
+  }
+}
+
+function MockRequest(remoteAddr, method, originalUrl) {
+  this.socket = { remoteAddress: remoteAddr };
+  this.originalUrl = originalUrl;
+  this.method = method;
+  this.httpVersionMajor = '5';
+  this.httpVersionMinor = '0';
+  this.headers = {};
+}
+
+class MockResponse extends EE {
+  constructor(code) {
+    super();
+    this.statusCode = code;
+    this.cachedHeaders = {};
+  }
+
+  end() {
+    this.emit('finish');
+  }
+
+  setHeader(key, value) {
+    this.cachedHeaders[key.toLowerCase()] = value;
+  }
+
+  getHeader(key) {
+    return this.cachedHeaders[key.toLowerCase()];
+  }
+
+  writeHead(code /* , headers */) {
+    this.statusCode = code;
+  }
+}
+
+test('log4js connect logger', (batch) => {
+  const clm = require('../../lib/connect-logger');
+
+  batch.test('with context config', (t) => {
+    const ml = new MockLogger();
+    const cl = clm(ml, { context: true });
+
+    t.beforeEach((done) => { ml.contexts = []; done(); });
+
+    t.test('response should be included in context', (assert) => {
+      const contexts = ml.contexts;
+      const req = new MockRequest('my.remote.addr', 'GET', 'http://url/hoge.png'); // not gif
+      const res = new MockResponse(200);
+      cl(req, res, () => { });
+      res.end('chunk', 'encoding');
+
+      assert.type(contexts, 'Array');
+      assert.equal(contexts.length, 1);
+      assert.type(contexts[0].res, MockResponse);
+      assert.end();
+    });
+
+    t.end();
+  });
+
+  batch.test('without context config', (t) => {
+    const ml = new MockLogger();
+    const cl = clm(ml, { });
+
+    t.beforeEach((done) => { ml.contexts = []; done(); });
+
+    t.test('response should not be included in context', (assert) => {
+      const contexts = ml.contexts;
+      const req = new MockRequest('my.remote.addr', 'GET', 'http://url/hoge.png'); // not gif
+      const res = new MockResponse(200);
+      cl(req, res, () => { });
+      res.end('chunk', 'encoding');
+
+      assert.type(contexts, 'Array');
+      assert.equal(contexts.length, 1);
+      assert.type(contexts[0].res, undefined);
+      assert.end();
+    });
+
+    t.end();
+  });
+
+  batch.end();
+});