fix(material/autocomplete): reopen panel on input click (#16020)

Currently if the user clicks an autocomplete to open it, selects an option and then clicks again, the panel won't open, because we use `focus` and the input was focused already. These changes add an extra `click` listener so the panel can reopen.

Fixes #15177.

(cherry picked from commit 16dea18)

src/material-experimental/mdc-autocomplete/autocomplete-trigger.ts

@@ -41,6 +41,7 @@ export const MAT_AUTOCOMPLETE_VALUE_ACCESSOR: any = {
     '(blur)': '_onTouched()',
     '(input)': '_handleInput($event)',
     '(keydown)': '_handleKeydown($event)',
+    '(click)': '_handleClick()',
   },
   exportAs: 'matAutocompleteTrigger',
   providers: [MAT_AUTOCOMPLETE_VALUE_ACCESSOR],

src/material-experimental/mdc-autocomplete/autocomplete.spec.ts

@@ -569,6 +569,31 @@ describe('MDC-based MatAutocomplete', () => {
 
       expect(input.hasAttribute('aria-haspopup')).toBe(false);
     });
+
+    it('should close the panel when pressing escape', fakeAsync(() => {
+      const trigger = fixture.componentInstance.trigger;
+
+      input.focus();
+      flush();
+      fixture.detectChanges();
+
+      expect(document.activeElement).withContext('Expected input to be focused.').toBe(input);
+      expect(trigger.panelOpen).withContext('Expected panel to be open.').toBe(true);
+
+      trigger.closePanel();
+      fixture.detectChanges();
+
+      expect(document.activeElement)
+        .withContext('Expected input to continue to be focused.')
+        .toBe(input);
+      expect(trigger.panelOpen).withContext('Expected panel to be closed.').toBe(false);
+
+      input.click();
+      flush();
+      fixture.detectChanges();
+
+      expect(trigger.panelOpen).withContext('Expected panel to reopen on click.').toBe(true);
+    }));
   });
 
   it('should not close the panel when clicking on the input', fakeAsync(() => {

src/material/autocomplete/autocomplete-trigger.ts

@@ -454,6 +454,12 @@ export abstract class _MatAutocompleteTriggerBase
     }
   }
 
+  _handleClick(): void {
+    if (this._canOpen() && !this.panelOpen) {
+      this.openPanel();
+    }
+  }
+
   /**
    * In "auto" mode, the label will animate down as soon as focus is lost.
    * This causes the value to jump when selecting an option with the mouse.
@@ -800,6 +806,7 @@ export abstract class _MatAutocompleteTriggerBase
     '(blur)': '_onTouched()',
     '(input)': '_handleInput($event)',
     '(keydown)': '_handleKeydown($event)',
+    '(click)': '_handleClick()',
   },
   exportAs: 'matAutocompleteTrigger',
   providers: [MAT_AUTOCOMPLETE_VALUE_ACCESSOR],

src/material/autocomplete/autocomplete.spec.ts

@@ -566,6 +566,31 @@ describe('MatAutocomplete', () => {
 
       expect(input.hasAttribute('aria-haspopup')).toBe(false);
     });
+
+    it('should close the panel when pressing escape', fakeAsync(() => {
+      const trigger = fixture.componentInstance.trigger;
+
+      input.focus();
+      flush();
+      fixture.detectChanges();
+
+      expect(document.activeElement).withContext('Expected input to be focused.').toBe(input);
+      expect(trigger.panelOpen).withContext('Expected panel to be open.').toBe(true);
+
+      trigger.closePanel();
+      fixture.detectChanges();
+
+      expect(document.activeElement)
+        .withContext('Expected input to continue to be focused.')
+        .toBe(input);
+      expect(trigger.panelOpen).withContext('Expected panel to be closed.').toBe(false);
+
+      input.click();
+      flush();
+      fixture.detectChanges();
+
+      expect(trigger.panelOpen).withContext('Expected panel to reopen on click.').toBe(true);
+    }));
   });
 
   it('should not close the panel when clicking on the input', fakeAsync(() => {

tools/public_api_guard/material/autocomplete.md

@@ -198,6 +198,8 @@ export abstract class _MatAutocompleteTriggerBase implements ControlValueAccesso
     closePanel(): void;
     connectedTo: _MatAutocompleteOriginBase;
     // (undocumented)
+    _handleClick(): void;
+    // (undocumented)
     _handleFocus(): void;
     // (undocumented)
     _handleInput(event: KeyboardEvent): void;