fix(forms): changes to status not always being emitted to statusChanges observable for async validators. (#42553)

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.

PR Close #42553

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_array_spec.ts

@@ -1055,6 +1055,23 @@ describe('FormArray', () => {
          expect(g.errors).toEqual({'async': true, 'other': true});
          expect(g.pending).toEqual(false);
        }));
+
+    it('should fire statusChanges events when async validators are added via options object',
+       fakeAsync(() => {
+         // The behavior is tested (in other spec files) for each of the model types (`FormControl`,
+         // `FormGroup` and `FormArray`).
+         let statuses: string[] = [];
+
+         // Create a form control with an async validator added via options object.
+         const asc = new FormArray([], {asyncValidators: [() => Promise.resolve(null)]});
+
+         // Subscribe to status changes.
+         asc.statusChanges.subscribe((status: any) => statuses.push(status));
+
+         // After a tick, the async validator should change status PENDING -> VALID.
+         tick();
+         expect(statuses).toEqual(['VALID']);
+       }));
   });
 
   describe('disable() & enable()', () => {

packages/forms/test/form_control_spec.ts

@@ -879,6 +879,22 @@ describe('FormControl', () => {
          tick();
        }));
 
+    it('should fire statusChanges events for async validators added via options object',
+       fakeAsync(() => {
+         // The behavior can be tested for each of the model types.
+         let statuses: string[] = [];
+
+         // Create a form control with an async validator added via options object.
+         const asc = new FormControl('', {asyncValidators: [() => Promise.resolve(null)]});
+
+         // Subscribe to status changes.
+         asc.statusChanges.subscribe((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'));
 

packages/forms/test/form_group_spec.ts

@@ -819,6 +819,21 @@ describe('FormGroup', () => {
       group = new FormGroup({'one': control});
     }));
 
+    it('should fire statusChanges events for async validators added via options object',
+       fakeAsync(() => {
+         // The behavior can be tested for each of the model types.
+         let statuses: string[] = [];
+
+         // Create a form control with an async validator added via options object.
+         const asc = new FormGroup({}, {asyncValidators: [() => Promise.resolve(null)]});
+
+         // Subscribe to status changes.
+         asc.statusChanges.subscribe((status: any) => statuses.push(status));
+
+         // After a tick, the async validator should change status PENDING -> VALID.
+         tick();
+         expect(statuses).toEqual(['VALID']);
+       }));
 
     // TODO(kara): update these tests to use fake Async
     it('should fire a statusChange if child has async validation change', done => {