fix(forms): changes to status not always being emitted to statusChang…

…es observable for async validators.

When a FormControl, FormArray, or FormGroup is first constructed, if an async validator is attached, the `statusChanges` observable should receive a message when the validator complete (i.e. pending -> valid/invalid). If the validator was provided as part of the constructor options, it was not fired at construction time, which is fixed in this PR.

Fixes #35309.

packages/forms/src/model.ts

@@ -1167,7 +1167,7 @@ export class FormControl extends AbstractControl {
       // `VALID` or `INVALID`.
       // The status should be broadcasted via the `statusChanges` observable, so we set `emitEvent`
       // to `true` to allow that during the control creation process.
-      emitEvent: !!asyncValidator
+      emitEvent: !!this.asyncValidator
     });
   }
 
@@ -1433,7 +1433,7 @@ export class FormGroup extends AbstractControl {
       // If `asyncValidator` is present, it will trigger control status change from `PENDING` to
       // `VALID` or `INVALID`. The status should be broadcasted via the `statusChanges` observable,
       // so we set `emitEvent` to `true` to allow that during the control creation process.
-      emitEvent: !!asyncValidator
+      emitEvent: !!this.asyncValidator
     });
   }
 
@@ -1887,7 +1887,7 @@ export class FormArray extends AbstractControl {
       // `VALID` or `INVALID`.
       // The status should be broadcasted via the `statusChanges` observable, so we set `emitEvent`
       // to `true` to allow that during the control creation process.
-      emitEvent: !!asyncValidator
+      emitEvent: !!this.asyncValidator
     });
   }
 

packages/forms/test/form_control_spec.ts

@@ -10,6 +10,7 @@ import {fakeAsync, tick} from '@angular/core/testing';
 import {FormControl, FormGroup, Validators} from '@angular/forms';
 
 import {FormArray} from '@angular/forms/src/model';
+import {expect} from '@angular/platform-browser/testing/src/matchers';
 import {asyncValidator, asyncValidatorReturningObservable} from './util';
 
 (function() {
@@ -879,6 +880,25 @@ describe('FormControl', () => {
          tick();
        }));
 
+    it('should fire statusChanges events for async validators transitioning from pending to valid',
+       fakeAsync(() => {
+         let statuses: string[] = [];
+
+         // Create a form control with an async validator.
+         const asc = new FormControl('', {asyncValidators: [control => Promise.resolve(null)]});
+
+         // Subscribe to status changes.
+         asc.statusChanges.subscribe({
+           next: (status: any) => {
+             statuses.push(status);
+           }
+         });
+
+         // After a tick, the async validator should change status PENDING -> VALID.
+         tick();
+         expect(statuses).toEqual(['VALID']);
+       }));
+
     it('should fire an event after the status has been updated to pending', fakeAsync(() => {
          const c = new FormControl('old', Validators.required, asyncValidator('expected'));