Ensure stack is present for custom errors (fixes #351) (#360)

Starting in Node 7, stack traces are computed eagerly when using Error.captureStackTrace [1]. As a result, the `message` and `name` properties of an error will not be included in the `stack` property if they are set after calling `Error.captureStackTrace`. As a workaround, set the properties before calling `Error.captureStackTrace`.

Note that this change in Node was reverted in V8 a few days ago [2], but it will probably be awhile until that fix appears in a Node release.

[1] https://chromium.googlesource.com/v8/v8.git/+/4feafee9d9741259e8ec3882fb61935a235ecc54
[2] https://chromium.googlesource.com/v8/v8.git/+/989d7b96f8352b502e2ede62e0b105e143d03837

lib/js-yaml/exception.js

@@ -6,6 +6,11 @@ function YAMLException(reason, mark) {
   // Super constructor
   Error.call(this);
 
+  this.name = 'YAMLException';
+  this.reason = reason;
+  this.mark = mark;
+  this.message = (this.reason || '(unknown reason)') + (this.mark ? ' ' + this.mark.toString() : '');
+
   // Include stack trace in error object
   if (Error.captureStackTrace) {
     // Chrome and NodeJS
@@ -14,11 +19,6 @@ function YAMLException(reason, mark) {
     // FF, IE 10+ and Safari 6+. Fallback for others
     this.stack = (new Error()).stack || '';
   }
-
-  this.name = 'YAMLException';
-  this.reason = reason;
-  this.mark = mark;
-  this.message = (this.reason || '(unknown reason)') + (this.mark ? ' ' + this.mark.toString() : '');
 }
 
 

test/issues/0351.js

@@ -0,0 +1,17 @@
+'use strict';
+
+
+var assert = require('assert');
+var yaml = require('../..');
+var readFileSync = require('fs').readFileSync;
+
+
+test('should include the error message in the error stack', function () {
+  try {
+    yaml.safeLoad(readFileSync(require('path').join(__dirname, '/0351.yml'), 'utf8'));
+  } catch (err) {
+    assert(err.stack.startsWith('YAMLException: end of the stream or a document separator is expected'));
+    return;
+  }
+  assert.fail(null, null, 'Expected an error to be thrown');
+});

test/issues/0351.yml

@@ -0,0 +1,4 @@
+# intentionally invalid yaml
+
+  foo: bar
+baz: qux