fix(forms): emit value changes after errors and status are set

Closes #4714

modules/angular2/src/core/forms/model.ts

@@ -107,13 +107,13 @@ export class AbstractControl {
 
     this._updateValue();
 
+    this._errors = this.validator(this);
+    this._status = isPresent(this._errors) ? INVALID : VALID;
+
     if (emitEvent) {
       ObservableWrapper.callNext(this._valueChanges, this._value);
     }
 
-    this._errors = this.validator(this);
-    this._status = isPresent(this._errors) ? INVALID : VALID;
-
     if (isPresent(this._parent) && !onlySelf) {
       this._parent.updateValueAndValidity({onlySelf: onlySelf, emitEvent: emitEvent});
     }

modules/angular2/test/core/forms/model_spec.ts

@@ -15,6 +15,7 @@ import {
 } from 'angular2/testing_internal';
 import {ControlGroup, Control, ControlArray, Validators} from 'angular2/core';
 import {ObservableWrapper} from 'angular2/src/core/facade/async';
+import {IS_DART} from '../../platform';
 
 export function main() {
   describe("Form Model", () => {
@@ -116,7 +117,7 @@ export function main() {
       describe("valueChanges", () => {
         var c;
 
-        beforeEach(() => { c = new Control("old"); });
+        beforeEach(() => { c = new Control("old", Validators.required); });
 
         it("should fire an event after the value has been updated",
            inject([AsyncTestCompleter], (async) => {
@@ -128,6 +129,19 @@ export function main() {
              c.updateValue("new");
            }));
 
+        // TODO: remove the if statement after making observable delivery sync
+        if (!IS_DART) {
+          it("should update set errors and status before emitting an event",
+             inject([AsyncTestCompleter], (async) => {
+               c.valueChanges.toRx().subscribe(value => {
+                 expect(c.valid).toEqual(false);
+                 expect(c.errors).toEqual({"required": true});
+                 async.done();
+               });
+               c.updateValue("");
+             }));
+        }
+
         it("should return a cold observable", inject([AsyncTestCompleter], (async) => {
              c.updateValue("will be ignored");
              ObservableWrapper.subscribe(c.valueChanges, (value) => {