fix(ZoneAwareError): Error should keep prototype chain and can be called without new

Fix #546, #554, #555

Author: JiaLiPassion

lib/zone.ts

@@ -1314,12 +1314,52 @@ const Zone: ZoneType = (function(global: any) {
   let frameParserStrategy = null;
   const stackRewrite = 'stackRewrite';
 
+  const assignAll = function(to, from) {
+    if (!to) {
+      return to;
+    }
+
+    if (from) {
+      let keys = Object.getOwnPropertyNames(from);
+      for (let i = 0; i < keys.length; i++) {
+        const key = keys[i];
+        // Avoid bugs when hasOwnProperty is shadowed
+        if (Object.prototype.hasOwnProperty.call(from, key)) {
+          to[key] = from[key];
+        }
+      }
+
+      // copy all properties from prototype
+      // in Error, property such as name/message is in Error's prototype
+      // but not enumerable, so we copy those properties through
+      // Error's prototype
+      const proto = Object.getPrototypeOf(from);
+      if (proto) {
+        let pKeys = Object.getOwnPropertyNames(proto);
+        for (let i = 0; i < pKeys.length; i++) {
+          const key = pKeys[i];
+          // skip constructor
+          if (key !== 'constructor') {
+            to[key] = from[key];
+          }
+        }
+      }
+    }
+    return to;
+  };
 
   /**
    * This is ZoneAwareError which processes the stack frame and cleans up extra frames as well as
    * adds zone information to it.
    */
   function ZoneAwareError() {
+    // make sure we have a valid this
+    // if this is undefined(call Error without new) or this is global
+    // or this is some other objects, we should force to create a
+    // valid ZoneAwareError by call Object.create()
+    if (!(this instanceof ZoneAwareError)) {
+      return ZoneAwareError.apply(Object.create(ZoneAwareError.prototype), arguments);
+    }
     // Create an Error.
     let error: Error = NativeError.apply(this, arguments);
 
@@ -1358,7 +1398,7 @@ const Zone: ZoneType = (function(global: any) {
       }
       error.stack = error.zoneAwareStack = frames.join('\n');
     }
-    return error;
+    return assignAll(this, error);
   }
 
   // Copy the prototype so that instanceof operator works as expected
@@ -1398,8 +1438,6 @@ const Zone: ZoneType = (function(global: any) {
     }
   });
 
-  // Now we need to populet the `blacklistedStackFrames` as well as find the
-
   // Now we need to populet the `blacklistedStackFrames` as well as find the
   // run/runGuraded/runTask frames. This is done by creating a detect zone and then threading
   // the execution through all of the above methods so that we can look at the stack trace and

test/common/Error.spec.ts

@@ -11,6 +11,62 @@ describe('ZoneAwareError', () => {
   // and there is no point in running them.
   if (!Error['stackRewrite']) return;
 
+  it('should keep error prototype chain correctly', () => {
+    class MyError extends Error {}
+    const myError = new MyError();
+    expect(myError instanceof Error).toBe(true);
+    expect(myError instanceof MyError).toBe(true);
+    expect(myError.stack).not.toBe(undefined);
+  });
+
+  it('should instanceof error correctly', () => {
+    let myError = Error('myError');
+    expect(myError instanceof Error).toBe(true);
+    let myError1 = Error.call(undefined, 'myError');
+    expect(myError1 instanceof Error).toBe(true);
+    let myError2 = Error.call(global, 'myError');
+    expect(myError2 instanceof Error).toBe(true);
+    let myError3 = Error.call({}, 'myError');
+    expect(myError3 instanceof Error).toBe(true);
+    let myError4 = Error.call({test: 'test'}, 'myError');
+    expect(myError4 instanceof Error).toBe(true);
+  });
+
+  it('should return error itself from constructor', () => {
+    class MyError1 extends Error {
+      constructor() {
+        const err: any = super('MyError1');
+        this.message = err.message;
+      }
+    }
+    let myError1 = new MyError1();
+    expect(myError1.message).toEqual('MyError1');
+    expect(myError1.name).toEqual('Error');
+  });
+
+  it('should return error by calling error directly', () => {
+    let myError = Error('myError');
+    expect(myError.message).toEqual('myError');
+    let myError1 = Error.call(undefined, 'myError');
+    expect(myError1.message).toEqual('myError');
+    let myError2 = Error.call(global, 'myError');
+    expect(myError2.message).toEqual('myError');
+    let myError3 = Error.call({}, 'myError');
+    expect(myError3.message).toEqual('myError');
+  });
+
+  it('should have browser specified property', () => {
+    let myError = new Error('myError');
+    if (Object.prototype.hasOwnProperty.call(Error.prototype, 'description')) {
+      // in IE, error has description property
+      expect((<any>myError).description).toEqual('myError');
+    }
+    if (Object.prototype.hasOwnProperty.call(Error.prototype, 'fileName')) {
+      // in firefox, error has fileName property
+      expect((<any>myError).fileName).toContain('zone');
+    }
+  });
+
   it('should show zone names in stack frames and remove extra frames', () => {
     const rootZone = getRootZone();
     const innerZone = rootZone.fork({name: 'InnerZone'});