fix(date-time-editor): handle iso date string for mask value 16.1.x (#14033)

* fix(date-time-editor): handle iso date string for mask value 16.1.x

* chore(*): add test for iso string date

---------

Co-authored-by: Nikolay Alipiev <[email protected]>

Author: dobromirts

projects/igniteui-angular/src/lib/directives/date-time-editor/date-time-editor.directive.spec.ts

@@ -378,11 +378,26 @@ describe('IgxDateTimeEditor', () => {
                 inputElement = fixture.debugElement.query(By.css('input'));
                 dateTimeEditorDirective = inputElement.injector.get(IgxDateTimeEditorDirective);
             });
+
             it('should properly update mask with inputFormat onInit', () => {
                 fixture = TestBed.createComponent(IgxDateTimeEditorBaseTestComponent);
                 fixture.detectChanges();
                 expect(fixture.componentInstance.dateEditor.elementRef.nativeElement.value).toEqual('09/11/2009');
             });
+
+            it('should update value and mask according to the display format and ISO string date as value', () => {
+                fixture.componentInstance.dateTimeFormat = 'dd/MM/yy';
+                fixture.componentInstance.displayFormat = 'shortDate';
+                dateTimeEditorDirective.value = new Date(2003, 3, 5).toISOString();
+                fixture.detectChanges();
+                inputElement.triggerEventHandler('focus', {});
+                fixture.detectChanges();
+                expect(dateTimeEditorDirective.mask).toEqual('00/00/00');
+                expect(inputElement.nativeElement.value).toEqual('05/04/03');
+                UIInteractions.simulateTyping('1', inputElement);
+                expect(inputElement.nativeElement.value).toEqual('15/04/03');
+            });
+
             it('should correctly display input format during user input', () => {
                 fixture.componentInstance.dateTimeFormat = 'dd/MM/yy';
                 fixture.detectChanges();

projects/igniteui-angular/src/lib/directives/date-time-editor/date-time-editor.directive.ts

@@ -552,7 +552,7 @@ export class IgxDateTimeEditorDirective extends IgxMaskDirective implements OnCh
 
   private getMaskedValue(): string {
     let mask = this.emptyMask;
-    if (DateTimeUtil.isValidDate(this.value)) {
+    if (DateTimeUtil.isValidDate(this.value) || DateTimeUtil.parseIsoDate(this.value)) {
       for (const part of this._inputDateParts) {
         if (part.type === DatePart.Literal) {
           continue;