Fix stringify producing unparseable output for quoted multiline strings

lib/hjson-stringify.js

@@ -166,10 +166,14 @@ module.exports = function(data, opt) {
     var i, a = string.replace(/\r/g, "").split('\n');
     gap += indent;
 
-    if (a.length === 1) {
-      // The string contains only a single line. We still use the multiline
-      // format as it avoids escaping the \ character (e.g. when used in a
-      // regex).
+    if (a.length === 1 && a[0][0] !== "'" && a[0][a[0].length - 1] !== "'") {
+      // The string contains only a single line and does not touch the ''' at
+      // either end, so we can use the compact multiline format. This still
+      // avoids escaping the \ character (e.g. when used in a regex). If the
+      // line started or ended with a quote we'd get a run of four or more
+      // quotes where it meets the ''' delimiter, which can't be told apart
+      // from the closing delimiter again, so those cases fall through to the
+      // block form below where the delimiters sit on their own line.
       return wrap(token.mstr, a[0]);
     } else {
       var res = eol + gap + token.mstr[0];

test/assets/mlStrQuote1_result.hjson

@@ -0,0 +1,15 @@
+{
+  bothQuotes:
+    '''
+    'Hello,\nWorld!'
+    '''
+  startQuote:
+    '''
+    'Hello,\nWorld!
+    '''
+  endQuote:
+    '''
+    #Hello,\nWorld!'
+    '''
+  safe: Hello,\nWorld!
+}

test/assets/mlStrQuote1_result.json

@@ -0,0 +1,6 @@
+{
+  "bothQuotes": "'Hello,\\nWorld!'",
+  "startQuote": "'Hello,\\nWorld!",
+  "endQuote": "#Hello,\\nWorld!'",
+  "safe": "Hello,\\nWorld!"
+}

test/assets/mlStrQuote1_test.json

@@ -0,0 +1,6 @@
+{
+  "bothQuotes": "'Hello,\\nWorld!'",
+  "startQuote": "'Hello,\\nWorld!",
+  "endQuote": "#Hello,\\nWorld!'",
+  "safe": "Hello,\\nWorld!"
+}

test/assets/testlist.txt

@@ -66,6 +66,7 @@ failStr7a_test.hjson
 failStr8a_test.hjson
 kan_test.hjson
 keys_test.hjson
+mlStrQuote1_test.json
 mltabs_test.json
 oa_test.hjson
 pass1_test.json