From dd20e68b0feb966c2a7439c947bbb4d46e3b19fe Mon Sep 17 00:00:00 2001
From: James M Snell <jasnell@gmail.com>
Date: Fri, 28 Apr 2017 09:06:10 -0700
Subject: [PATCH] process: add optional detail to process emitWarning

Adds a new method signature variant for process.emitWarning()
that accepts an options object. The options object may include
a new `detail` option that allows additional detail text to be
associated with the warning. By default, this additional text
will be printed to stderr along with the warning, and included
on the Warning Error object using the `.detail` property.

e.g.

```js
process.emitWarning('A message', {
  code: 'WARNING123',
  detail: 'This is additional detail'
});
// Emits:
// (node {pid}) [WARNING123] Warning: A message
// This is additional detail
```

PR-URL: https://github.com/nodejs/node/pull/12725
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
---
 doc/api/process.md                        | 56 ++++++++++++++++++++--
 lib/internal/process/warning.js           | 30 +++++++-----
 test/parallel/test-process-emitwarning.js | 57 +++++++++++++++--------
 3 files changed, 107 insertions(+), 36 deletions(-)

diff --git a/doc/api/process.md b/doc/api/process.md
index 3f853e55116632..133e3f7de5f197 100644
--- a/doc/api/process.md
+++ b/doc/api/process.md
@@ -637,6 +637,52 @@ process's [`ChildProcess.disconnect()`][].
 If the Node.js process was not spawned with an IPC channel,
 `process.disconnect()` will be `undefined`.
 
+## process.emitWarning(warning[, options])
+<!-- YAML
+added: REPLACEME
+-->
+
+* `warning` {string|Error} The warning to emit.
+* `options` {Object}
+  * `type` {string} When `warning` is a String, `type` is the name to use
+    for the *type* of warning being emitted. Default: `Warning`.
+  * `code` {string} A unique identifier for the warning instance being emitted.
+  * `ctor` {Function} When `warning` is a String, `ctor` is an optional
+    function used to limit the generated stack trace. Default
+    `process.emitWarning`
+  * `detail` {string} Additional text to include with the error.
+
+The `process.emitWarning()` method can be used to emit custom or application
+specific process warnings. These can be listened for by adding a handler to the
+[`process.on('warning')`][process_warning] event.
+
+```js
+// Emit a warning with a code and additional detail.
+process.emitWarning('Something happened!', {
+  code: 'MY_WARNING',
+  detail: 'This is some additional information'
+});
+// Emits:
+// (node:56338) [MY_WARNING] Warning: Something happened!
+// This is some additional information
+```
+
+In this example, an `Error` object is generated internally by
+`process.emitWarning()` and passed through to the
+[`process.on('warning')`][process_warning] event.
+
+```js
+process.on('warning', (warning) => {
+  console.warn(warning.name);    // 'Warning'
+  console.warn(warning.message); // 'Something happened!'
+  console.warn(warning.code);    // 'MY_WARNING'
+  console.warn(warning.stack);   // Stack trace
+  console.warn(warning.detail);  // 'This is some additional information'
+});
+```
+
+If `warning` is passed as an `Error` object, the `options` argument is ignored.
+
 ## process.emitWarning(warning[, type[, code]][, ctor])
 <!-- YAML
 added: v6.0.0
@@ -655,13 +701,13 @@ specific process warnings. These can be listened for by adding a handler to the
 [`process.on('warning')`][process_warning] event.
 
 ```js
-// Emit a warning using a string...
+// Emit a warning using a string.
 process.emitWarning('Something happened!');
 // Emits: (node: 56338) Warning: Something happened!
 ```
 
 ```js
-// Emit a warning using a string and a type...
+// Emit a warning using a string and a type.
 process.emitWarning('Something Happened!', 'CustomWarning');
 // Emits: (node:56338) CustomWarning: Something Happened!
 ```
@@ -689,14 +735,14 @@ If `warning` is passed as an `Error` object, it will be passed through to the
 `code` and `ctor` arguments will be ignored):
 
 ```js
-// Emit a warning using an Error object...
-const myWarning = new Error('Warning! Something happened!');
+// Emit a warning using an Error object.
+const myWarning = new Error('Something happened!');
 // Use the Error name property to specify the type name
 myWarning.name = 'CustomWarning';
 myWarning.code = 'WARN001';
 
 process.emitWarning(myWarning);
-// Emits: (node:56338) [WARN001] CustomWarning: Warning! Something happened!
+// Emits: (node:56338) [WARN001] CustomWarning: Something happened!
 ```
 
 A `TypeError` is thrown if `warning` is anything other than a string or `Error`
diff --git a/lib/internal/process/warning.js b/lib/internal/process/warning.js
index 86fe491e576668..fa77a8f3f59ce6 100644
--- a/lib/internal/process/warning.js
+++ b/lib/internal/process/warning.js
@@ -90,30 +90,37 @@ function setupProcessWarnings() {
       if (isDeprecation && process.noDeprecation) return;
       const trace = process.traceProcessWarnings ||
                     (isDeprecation && process.traceDeprecation);
+      let msg = `${prefix}`;
+      if (warning.code)
+        msg += `[${warning.code}] `;
       if (trace && warning.stack) {
-        if (warning.code) {
-          output(`${prefix}[${warning.code}] ${warning.stack}`);
-        } else {
-          output(`${prefix}${warning.stack}`);
-        }
+        msg += `${warning.stack}`;
       } else {
         const toString =
           typeof warning.toString === 'function' ?
             warning.toString : Error.prototype.toString;
-        if (warning.code) {
-          output(`${prefix}[${warning.code}] ${toString.apply(warning)}`);
-        } else {
-          output(`${prefix}${toString.apply(warning)}`);
-        }
+        msg += `${toString.apply(warning)}`;
       }
+      if (typeof warning.detail === 'string') {
+        msg += `\n${warning.detail}`;
+      }
+      output(msg);
     });
   }
 
   // process.emitWarning(error)
   // process.emitWarning(str[, type[, code]][, ctor])
+  // process.emitWarning(str[, options])
   process.emitWarning = function(warning, type, code, ctor) {
     const errors = lazyErrors();
-    if (typeof type === 'function') {
+    var detail;
+    if (type !== null && typeof type === 'object' && !Array.isArray(type)) {
+      ctor = type.ctor;
+      code = type.code;
+      if (typeof type.detail === 'string')
+        detail = type.detail;
+      type = type.type || 'Warning';
+    } else if (typeof type === 'function') {
       ctor = type;
       code = undefined;
       type = 'Warning';
@@ -130,6 +137,7 @@ function setupProcessWarnings() {
       warning = new Error(warning);
       warning.name = String(type || 'Warning');
       if (code !== undefined) warning.code = code;
+      if (detail !== undefined) warning.detail = detail;
       Error.captureStackTrace(warning, ctor || process.emitWarning);
     }
     if (!(warning instanceof Error)) {
diff --git a/test/parallel/test-process-emitwarning.js b/test/parallel/test-process-emitwarning.js
index bebdc989a2dbff..61ca05cfe9a011 100644
--- a/test/parallel/test-process-emitwarning.js
+++ b/test/parallel/test-process-emitwarning.js
@@ -4,30 +4,48 @@
 
 const common = require('../common');
 const assert = require('assert');
-const util = require('util');
+
+const testMsg = 'A Warning';
+const testCode = 'CODE001';
+const testDetail = 'Some detail';
+const testType = 'CustomWarning';
 
 process.on('warning', common.mustCall((warning) => {
   assert(warning);
   assert(/^(Warning|CustomWarning)/.test(warning.name));
-  assert.strictEqual(warning.message, 'A Warning');
-  if (warning.code) assert.strictEqual(warning.code, 'CODE001');
-}, 8));
-
-process.emitWarning('A Warning');
-process.emitWarning('A Warning', 'CustomWarning');
-process.emitWarning('A Warning', CustomWarning);
-process.emitWarning('A Warning', 'CustomWarning', CustomWarning);
-process.emitWarning('A Warning', 'CustomWarning', 'CODE001');
-
-function CustomWarning() {
-  Error.call(this);
-  this.name = 'CustomWarning';
-  this.message = 'A Warning';
-  this.code = 'CODE001';
-  Error.captureStackTrace(this, CustomWarning);
+  assert.strictEqual(warning.message, testMsg);
+  if (warning.code) assert.strictEqual(warning.code, testCode);
+  if (warning.detail) assert.strictEqual(warning.detail, testDetail);
+}, 15));
+
+class CustomWarning extends Error {
+  constructor() {
+    super();
+    this.name = testType;
+    this.message = testMsg;
+    this.code = testCode;
+    Error.captureStackTrace(this, CustomWarning);
+  }
 }
-util.inherits(CustomWarning, Error);
-process.emitWarning(new CustomWarning());
+
+[
+  [testMsg],
+  [testMsg, testType],
+  [testMsg, CustomWarning],
+  [testMsg, testType, CustomWarning],
+  [testMsg, testType, testCode],
+  [testMsg, { type: testType }],
+  [testMsg, { type: testType, code: testCode }],
+  [testMsg, { type: testType, code: testCode, detail: testDetail }],
+  [new CustomWarning()],
+  // detail will be ignored for the following. No errors thrown
+  [testMsg, { type: testType, code: testCode, detail: true }],
+  [testMsg, { type: testType, code: testCode, detail: [] }],
+  [testMsg, { type: testType, code: testCode, detail: null }],
+  [testMsg, { type: testType, code: testCode, detail: 1 }]
+].forEach((i) => {
+  assert.doesNotThrow(() => process.emitWarning.apply(null, i));
+});
 
 const warningNoToString = new CustomWarning();
 warningNoToString.toString = null;
@@ -47,7 +65,6 @@ assert.throws(() => process.emitWarning(1), expectedError);
 assert.throws(() => process.emitWarning({}), expectedError);
 assert.throws(() => process.emitWarning(true), expectedError);
 assert.throws(() => process.emitWarning([]), expectedError);
-assert.throws(() => process.emitWarning('', {}), expectedError);
 assert.throws(() => process.emitWarning('', '', {}), expectedError);
 assert.throws(() => process.emitWarning('', 1), expectedError);
 assert.throws(() => process.emitWarning('', '', 1), expectedError);