fix(core): fix #405, refine the error message when zone.js already loaded

lib/zone.ts

@@ -608,7 +608,19 @@ type AmbientZoneDelegate = ZoneDelegate;
 
 const Zone: ZoneType = (function(global: any) {
  if (global['Zone']) {
- throw new Error('Zone already loaded.');
+ let zoneAlreadyLoadedMessage: string = 'Zone already loaded.';
+ // try to findout the already loaded zone.js script file
+ // require the loaded zone.js version to be newer than 0.8.6
+ try {
+ const LoadedZone: any = global['Zone'];
+ const scriptFileName: string = LoadedZone['__zone_symbol__scriptFileName'];
+ if (scriptFileName) {
+ zoneAlreadyLoadedMessage =
+ 'Zone already loaded. The loaded Zone.js script file seems to be ' + scriptFileName;
+ }
+ } catch (error) {
+ }
+ throw new Error(zoneAlreadyLoadedMessage);
  }
 
  const NO_ZONE = {name: 'NO ZONE'};
@@ -623,12 +635,17 @@ const Zone: ZoneType = (function(global: any) {
 
  static assertZonePatched() {
  if (global.Promise !== ZoneAwarePromise) {
+ // try to findout the already loaded zone.js script file
+ // require the loaded zone.js version to be newer than 0.8.6
+ const scriptFileName: string = (Zone as any)[__symbol__('scriptFileName')];
+ const scriptFileErrorMessage: string =
+ scriptFileName ? 'the loaded Zone.js script file seems to be ' + scriptFileName : '';
  throw new Error(
  'Zone.js has detected that ZoneAwarePromise `(window|global).Promise` ' +
  'has been overwritten.\n' +
  'Most likely cause is that a Promise polyfill has been loaded ' +
  'after Zone.js (Polyfilling Promise api is not necessary when zone.js is loaded. ' +
- 'If you must load one, do so before loading zone.js.)');
+ 'If you must load one, do so before loading zone.js.)' + scriptFileErrorMessage);
  }
  }
 
@@ -1803,11 +1820,24 @@ const Zone: ZoneType = (function(global: any) {
  // Chrome: at Zone.run (http://localhost:9876/base/build/lib/zone.js:100:24)
  // FireFox: Zone.prototype.run@http://localhost:9876/base/build/lib/zone.js:101:24
  // Safari: run@http://localhost:9876/base/build/lib/zone.js:101:24
- let fnName: string = frame.split('(')[0].split('@')[0];
+ let frameParts: string[] = frame.split('(');
+ let fnNamePart: string = frameParts[0];
+
+ let fnName: string = fnNamePart.split('@')[0];
  let frameType = FrameType.transition;
  if (fnName.indexOf('ZoneAwareError') !== -1) {
  zoneAwareFrame1 = frame;
  zoneAwareFrame2 = frame.replace('Error.', '');
+
+ // try to find the filename where zone.js live with
+ let fileNamePart1: string = frameParts.length > 1 ? frameParts[1] : fnNamePart;
+ let fileNameParts: string[] = fileNamePart1.split('@');
+ let fileNamePart2: string =
+ fileNameParts.length > 1 ? fileNameParts[1] : fileNameParts[0];
+ // Keep a script file name in Zone, so when zone.js report 'already loaded'
+ // error, it can report which file include the loaded zone.js
+ (Zone as any)[__symbol__('scriptFileName')] = fileNamePart2;
+
  blackListedStackFrames[zoneAwareFrame2] = FrameType.blackList;
  }
  if (fnName.indexOf('runGuarded') !== -1) {

test/common/zone.spec.ts

@@ -328,12 +328,24 @@ describe('Zone', function() {
 
  it('should throw when Promise has been patched', () => {
  class WrongPromise {}
+ const errorMessage =
+ 'Zone.js has detected that ZoneAwarePromise `(window|global).Promise` ' +
+ 'has been overwritten.';
+ const errorScriptMessage = 'the loaded Zone.js script file seems to be';
 
  const ZoneAwarePromise = global.Promise;
  global.Promise = WrongPromise;
  try {
  expect(ZoneAwarePromise).toBeTruthy();
- expect(() => Zone.assertZonePatched()).toThrow();
+ try {
+ Zone.assertZonePatched();
+ } catch (error) {
+ expect(error.message).toContain(errorMessage);
+ expect(error.message).toContain(errorScriptMessage);
+ const idx = error.message.lastIndexOf(errorScriptMessage);
+ const fileName: string = error.message.slice(idx + errorScriptMessage.length);
+ expect(fileName).toContain('zone.js');
+ }
  } finally {
  // restore it.
  global.Promise = ZoneAwarePromise;