diff -r 000000000000 -r 6474c204b198 toolkit/components/jsdownloads/test/unit/test_DownloadCore.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/jsdownloads/test/unit/test_DownloadCore.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Tests the main download interfaces using DownloadCopySaver.
+ */
+
+"use strict";
+
+XPCOMUtils.defineLazyModuleGetter(this, "DownloadError",
+                                  "resource://gre/modules/DownloadCore.jsm");
+
+////////////////////////////////////////////////////////////////////////////////
+//// Execution of common tests
+
+let gUseLegacySaver = false;
+
+let scriptFile = do_get_file("common_test_Download.js");
+Services.scriptloader.loadSubScript(NetUtil.newURI(scriptFile).spec);
+
+////////////////////////////////////////////////////////////////////////////////
+//// Tests
+
+/**
+ * Tests the DownloadError object.
+ */
+add_task(function test_DownloadError()
+{
+  let error = new DownloadError({ result: Cr.NS_ERROR_NOT_RESUMABLE,
+                                  message: "Not resumable."});
+  do_check_eq(error.result, Cr.NS_ERROR_NOT_RESUMABLE);
+  do_check_eq(error.message, "Not resumable.");
+  do_check_false(error.becauseSourceFailed);
+  do_check_false(error.becauseTargetFailed);
+  do_check_false(error.becauseBlocked);
+  do_check_false(error.becauseBlockedByParentalControls);
+
+  error = new DownloadError({ message: "Unknown error."});
+  do_check_eq(error.result, Cr.NS_ERROR_FAILURE);
+  do_check_eq(error.message, "Unknown error.");
+
+  error = new DownloadError({ result: Cr.NS_ERROR_NOT_RESUMABLE });
+  do_check_eq(error.result, Cr.NS_ERROR_NOT_RESUMABLE);
+  do_check_true(error.message.indexOf("Exception") > 0);
+
+  // becauseSourceFailed will be set, but not the unknown property.
+  error = new DownloadError({ message: "Unknown error.",
+                              becauseSourceFailed: true,
+                              becauseUnknown: true });
+  do_check_true(error.becauseSourceFailed);
+  do_check_false("becauseUnknown" in error);
+
+  error = new DownloadError({ result: Cr.NS_ERROR_MALFORMED_URI,
+                              inferCause: true });
+  do_check_eq(error.result, Cr.NS_ERROR_MALFORMED_URI);
+  do_check_true(error.becauseSourceFailed);
+  do_check_false(error.becauseTargetFailed);
+  do_check_false(error.becauseBlocked);
+  do_check_false(error.becauseBlockedByParentalControls);
+
+  // This test does not set inferCause, so becauseSourceFailed will not be set.
+  error = new DownloadError({ result: Cr.NS_ERROR_MALFORMED_URI });
+  do_check_eq(error.result, Cr.NS_ERROR_MALFORMED_URI);
+  do_check_false(error.becauseSourceFailed);
+
+  error = new DownloadError({ result: Cr.NS_ERROR_FILE_INVALID_PATH,
+                              inferCause: true });
+  do_check_eq(error.result, Cr.NS_ERROR_FILE_INVALID_PATH);
+  do_check_false(error.becauseSourceFailed);
+  do_check_true(error.becauseTargetFailed);
+  do_check_false(error.becauseBlocked);
+  do_check_false(error.becauseBlockedByParentalControls);
+
+  error = new DownloadError({ becauseBlocked: true });
+  do_check_eq(error.message, "Download blocked.");
+  do_check_false(error.becauseSourceFailed);
+  do_check_false(error.becauseTargetFailed);
+  do_check_true(error.becauseBlocked);
+  do_check_false(error.becauseBlockedByParentalControls);
+
+  error = new DownloadError({ becauseBlockedByParentalControls: true });
+  do_check_eq(error.message, "Download blocked.");
+  do_check_false(error.becauseSourceFailed);
+  do_check_false(error.becauseTargetFailed);
+  do_check_true(error.becauseBlocked);
+  do_check_true(error.becauseBlockedByParentalControls);
+});
+
+////////////////////////////////////////////////////////////////////////////////
+//// Termination
+
+let tailFile = do_get_file("tail.js");
+Services.scriptloader.loadSubScript(NetUtil.newURI(tailFile).spec);