Use msgstr[0] when stringifying an untranslated plural item.

lib/po.js

@@ -321,8 +321,11 @@ PO.Item.prototype.toString = function () {
                     lines = lines.concat(mkObsolete + _process(keyword, t, i));
                 });
             } else {
+                var index = (self.msgid_plural && Array.isArray(text)) ?
+                    0 :
+                    undefined;
                 text = Array.isArray(text) ? text.join() : text;
-                var processed = _process(keyword, text);
+                var processed = _process(keyword, text, index);
                 //handle \n in single-line texts (can not be handled in _escape)
                 for (var i = 1; i < processed.length - 1; i++) {
                     processed[i] = processed[i].slice(0, -1) + '\\n"';

test/fixtures/plural.po

@@ -0,0 +1,32 @@
+# French translation of Link (6.x-2.9)
+# Copyright (c) 2011 by the French translation team
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: Link (6.x-2.9)\n"
+"POT-Creation-Date: 2011-12-31 23:39+0000\n"
+"PO-Revision-Date: 2013-12-17 14:59+0100\n"
+"Language-Team: French\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n > 1);\n"
+"Last-Translator: Ruben Vermeersch <ruben@rocketeer.be>\n"
+"Language: fr\n"
+"X-Generator: Poedit 1.6.2\n"
+
+# correct plurals, with translation
+msgid "1 source"
+msgid_plural "{{$count}} sources"
+msgstr[0] "1 source"
+msgstr[1] "{{$count}} sources"
+
+# correct plurals, with no translation
+msgid "1 destination"
+msgid_plural "{{$count}} destinations"
+msgstr[0] ""
+
+# incorrect plurals, with no translation
+msgid "1 mistake"
+msgid_plural "{{$count}} mistakes"
+msgstr ""

test/write.js

@@ -16,6 +16,21 @@ function assertHasLine(str, line) {
     assert(found, 'Could not find line: ' + line);
 }
 
+function assertHasContiguousLines(str, assertedLines) {
+    var assertedLinesJoined = assertedLines.join('\n');
+
+    var trimmedStr = str
+        .split('\n')
+        .map(function (line) {
+            return line.trim();
+        })
+        .join('\n');
+
+    var found = trimmedStr.indexOf(assertedLinesJoined) !== -1;
+
+    assert(found, 'Could not find lines: \n' + assertedLinesJoined);
+}
+
 function assertDoesntHaveLine(str, line) {
     var lines = str.split('\n');
     var found = false;
@@ -103,6 +118,38 @@ describe('Write', function () {
         assertHasLine(str, '#~ msgstr "also not sure"');
     });
 
+    describe('plurals', function () {
+        it('should write multiple msgstrs', function () {
+            var input = fs.readFileSync(__dirname + '/fixtures/plural.po', 'utf8');
+            var po = PO.parse(input);
+            var str = po.toString();
+            assertHasContiguousLines(str, [
+                'msgstr[0] "1 source"',
+                'msgstr[1] "{{$count}} sources"'
+            ]);
+        });
+
+        it('should write msgstr[0] when there is no translation', function () {
+            var input = fs.readFileSync(__dirname + '/fixtures/plural.po', 'utf8');
+            var po = PO.parse(input);
+            var str = po.toString();
+            assertHasContiguousLines(str, [
+                'msgid_plural "{{$count}} destinations"',
+                'msgstr[0] ""'
+            ]);
+        });
+
+        it('should write msgstr[0] when there is no translation and empty plural translation is stored in msgstr ""', function () {
+            var input = fs.readFileSync(__dirname + '/fixtures/plural.po', 'utf8');
+            var po = PO.parse(input);
+            var str = po.toString();
+            assertHasContiguousLines(str, [
+                'msgid_plural "{{$count}} mistakes"',
+                'msgstr[0] ""'
+            ]);
+        });
+    });
+
     describe('C-Strings', function () {
         it('should escape "', function () {
             var item = new PO.Item();