feat(spec): log URL in error when attempting XHR from FakeAsyncTestZone (#893)

Save the URL from xhr.open and log it when throwing an error from FakeAsyncTestZone when the XHR send it attempted. This would make it easier to debug such errors from a fakeAsync test.

Author: vikerman

lib/browser/browser.ts

@@ -82,9 +82,11 @@ Zone.__load_patch('XHR', (global: any, Zone: ZoneType, api: _ZonePrivate) => {
   const XHR_SYNC = zoneSymbol('xhrSync');
   const XHR_LISTENER = zoneSymbol('xhrListener');
   const XHR_SCHEDULED = zoneSymbol('xhrScheduled');
+  const XHR_URL = zoneSymbol('xhrURL');
 
   interface XHROptions extends TaskData {
     target: any;
+    url: string;
     args: any[];
     aborted: boolean;
   }
@@ -158,6 +160,7 @@ Zone.__load_patch('XHR', (global: any, Zone: ZoneType, api: _ZonePrivate) => {
     const openNative: Function = patchMethod(
         window.XMLHttpRequest.prototype, 'open', () => function(self: any, args: any[]) {
           self[XHR_SYNC] = args[2] == false;
+          self[XHR_URL] = args[1];
           return openNative.apply(self, args);
         });
 
@@ -169,8 +172,14 @@ Zone.__load_patch('XHR', (global: any, Zone: ZoneType, api: _ZonePrivate) => {
             // if the XHR is sync there is no task to schedule, just execute the code.
             return sendNative.apply(self, args);
           } else {
-            const options: XHROptions =
-                {target: self, isPeriodic: false, delay: null, args: args, aborted: false};
+            const options: XHROptions = {
+              target: self,
+              url: self[XHR_URL],
+              isPeriodic: false,
+              delay: null,
+              args: args,
+              aborted: false
+            };
             return zone.scheduleMacroTask(
                 XMLHTTPREQUEST_SOURCE, placeholderCallback, options, scheduleTask, clearTask);
           }

lib/zone-spec/fake-async-test.ts

@@ -339,7 +339,9 @@
                   this._setInterval(task.invoke, task.data['delay'], (task.data as any)['args']);
               break;
             case 'XMLHttpRequest.send':
-              throw new Error('Cannot make XHRs from within a fake async test.');
+              throw new Error(
+                  'Cannot make XHRs from within a fake async test. Request URL: ' +
+                  (task.data as any)['url']);
             case 'requestAnimationFrame':
             case 'webkitRequestAnimationFrame':
             case 'mozRequestAnimationFrame':

test/zone-spec/fake-async-test.spec.ts

@@ -664,25 +664,26 @@ describe('FakeAsyncTestZoneSpec', () => {
     });
   });
 
-  describe('XHRs', ifEnvSupports('XMLHttpRequest', () => {
-             it('should throw an exception if an XHR is initiated in the zone', () => {
-               expect(() => {
-                 fakeAsyncTestZone.run(() => {
-                   let finished = false;
-                   let req = new XMLHttpRequest();
-
-                   req.onreadystatechange = () => {
-                     if (req.readyState === XMLHttpRequest.DONE) {
-                       finished = true;
-                     }
-                   };
-
-                   req.open('GET', '/', true);
-                   req.send();
-                 });
-               }).toThrowError('Cannot make XHRs from within a fake async test.');
-             });
-           }));
+  describe(
+      'XHRs', ifEnvSupports('XMLHttpRequest', () => {
+        it('should throw an exception if an XHR is initiated in the zone', () => {
+          expect(() => {
+            fakeAsyncTestZone.run(() => {
+              let finished = false;
+              let req = new XMLHttpRequest();
+
+              req.onreadystatechange = () => {
+                if (req.readyState === XMLHttpRequest.DONE) {
+                  finished = true;
+                }
+              };
+
+              req.open('GET', '/test', true);
+              req.send();
+            });
+          }).toThrowError('Cannot make XHRs from within a fake async test. Request URL: /test');
+        });
+      }));
 
   describe('node process', ifEnvSupports(supportNode, () => {
              it('should be able to schedule microTask with additional arguments', () => {