Add equals sign to list of unsafe values for plain styling

lib/js-yaml/dumper.js

@@ -23,6 +23,7 @@ var CHAR_ASTERISK             = 0x2A; /* * */
 var CHAR_COMMA                = 0x2C; /* , */
 var CHAR_MINUS                = 0x2D; /* - */
 var CHAR_COLON                = 0x3A; /* : */
+var CHAR_EQUALS               = 0x3D; /* = */
 var CHAR_GREATER_THAN         = 0x3E; /* > */
 var CHAR_QUESTION             = 0x3F; /* ? */
 var CHAR_COMMERCIAL_AT        = 0x40; /* @ */
@@ -220,16 +221,17 @@ function isPlainSafeFirst(c) {
     && c !== CHAR_RIGHT_SQUARE_BRACKET
     && c !== CHAR_LEFT_CURLY_BRACKET
     && c !== CHAR_RIGHT_CURLY_BRACKET
-    // | “#” | “&” | “*” | “!” | “|” | “>” | “'” | “"”
+    // | “#” | “&” | “*” | “!” | “|” | “=” | “>” | “'”
     && c !== CHAR_SHARP
     && c !== CHAR_AMPERSAND
     && c !== CHAR_ASTERISK
     && c !== CHAR_EXCLAMATION
     && c !== CHAR_VERTICAL_LINE
+    && c !== CHAR_EQUALS
     && c !== CHAR_GREATER_THAN
     && c !== CHAR_SINGLE_QUOTE
+    // | “"” | “%” | “@” | “`”)
     && c !== CHAR_DOUBLE_QUOTE
-    // | “%” | “@” | “`”)
     && c !== CHAR_PERCENT
     && c !== CHAR_COMMERCIAL_AT
     && c !== CHAR_GRAVE_ACCENT;

test/issues/0519.js

@@ -0,0 +1,10 @@
+'use strict';
+
+var assert = require('assert');
+var yaml   = require('../../');
+
+test('Loader should not strip quotes for lines containing equals sign', function () {
+  var line_with_equals_sign = "'='\n";
+  var result_of_load_and_dump = yaml.dump(yaml.load(line_with_equals_sign));
+  assert.strictEqual(line_with_equals_sign, result_of_load_and_dump);
+});