diff -r 000000000000 -r 6474c204b198 modules/libjar/zipwriter/test/unit/test_sync.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/modules/libjar/zipwriter/test/unit/test_sync.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,57 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+// Values taken from using zipinfo to list the test.zip contents
+var TESTS = [
+  {
+    name: "test.txt",
+    size: 232,
+    crc: 0x0373ac26
+  },
+  {
+    name: "test.png",
+    size: 3402,
+    crc: 0x504a5c30
+  }
+];
+
+function run_test()
+{
+  zipW.open(tmpFile, PR_RDWR | PR_CREATE_FILE | PR_TRUNCATE);
+
+  var size = 0;
+  for (var i = 0; i < TESTS.length; i++) {
+    var source = do_get_file(DATA_DIR + TESTS[i].name);
+    zipW.addEntryFile(TESTS[i].name, Ci.nsIZipWriter.COMPRESSION_NONE, source,
+                      false);
+    size += ZIP_FILE_HEADER_SIZE + ZIP_CDS_HEADER_SIZE +
+            (ZIP_EXTENDED_TIMESTAMP_SIZE * 2) +
+            (TESTS[i].name.length*2) + TESTS[i].size;
+  }
+
+  zipW.close();
+  size += ZIP_EOCDR_HEADER_SIZE;
+
+  do_check_eq(size, tmpFile.fileSize);
+
+  // Test the stored data with the zipreader
+  var zipR = new ZipReader(tmpFile);
+
+  for (var i = 0; i < TESTS.length; i++) {
+    var source = do_get_file(DATA_DIR + TESTS[i].name);
+    do_check_true(zipR.hasEntry(TESTS[i].name));
+
+    var entry = zipR.getEntry(TESTS[i].name);
+    do_check_eq(entry.realSize, TESTS[i].size);
+    do_check_eq(entry.size, TESTS[i].size);
+    do_check_eq(entry.CRC32, TESTS[i].crc);
+    do_check_eq(Math.floor(entry.lastModifiedTime / PR_USEC_PER_SEC),
+                Math.floor(source.lastModifiedTime / PR_MSEC_PER_SEC));
+
+    zipR.test(TESTS[i].name);
+  }
+
+  zipR.close();
+}