fix(material/chips): allow for role to be overwritten on chip list and chip (#15794)

Allows for the ARIA `role` of the `mat-chip-list` and `mat-chip` to be overwritten.

Fixes #15787.

Author: crisbeto

src/material-experimental/mdc-chips/chip-grid.spec.ts

@@ -103,6 +103,13 @@ describe('MDC-based MatChipGrid', () => {
 
         expect(chipGridNativeElement.hasAttribute('role')).toBe(false);
       });
+
+      it('should be able to set a custom role', () => {
+        testComponent.role = 'listbox';
+        fixture.detectChanges();
+
+        expect(chipGridNativeElement.getAttribute('role')).toBe('listbox');
+      });
     });
 
     describe('focus behaviors', () => {
@@ -1028,7 +1035,7 @@ describe('MDC-based MatChipGrid', () => {
 
 @Component({
   template: `
-    <mat-chip-grid [tabIndex]="tabIndex" #chipGrid>
+    <mat-chip-grid [tabIndex]="tabIndex" [role]="role" #chipGrid>
       <mat-chip-row *ngFor="let i of chips"
                     [editable]="editable">
         {{name}} {{i + 1}}
@@ -1041,6 +1048,7 @@ class StandardChipGrid {
   tabIndex: number = 0;
   chips = [0, 1, 2, 3, 4];
   editable = false;
+  role: string | null = null;
 }
 
 @Component({

src/material-experimental/mdc-chips/chip-grid.ts

@@ -143,6 +143,8 @@ export class MatChipGrid
   /** The chip input to add more chips */
   protected _chipInput: MatChipTextControl;
 
+  protected override _defaultRole = 'grid';
+
   /**
    * Function when touched. Set as part of ControlValueAccessor implementation.
    * @docs-private
@@ -186,11 +188,6 @@ export class MatChipGrid
     );
   }
 
-  /** The ARIA role applied to the chip grid. */
-  override get role(): string | null {
-    return this.empty ? null : 'grid';
-  }
-
   /**
    * Implemented as part of MatFormFieldControl.
    * @docs-private

src/material-experimental/mdc-chips/chip-listbox.spec.ts

@@ -89,6 +89,13 @@ describe('MDC-based MatChipListbox', () => {
         expect(chipListboxNativeElement.hasAttribute('role')).toBe(false);
       });
 
+      it('should be able to set a custom role', () => {
+        testComponent.role = 'grid';
+        fixture.detectChanges();
+
+        expect(chipListboxNativeElement.getAttribute('role')).toBe('grid');
+      });
+
       it('should not set aria-required when it does not have a role', () => {
         testComponent.chips = [];
         fixture.detectChanges();
@@ -745,7 +752,7 @@ describe('MDC-based MatChipListbox', () => {
 
 @Component({
   template: `
-    <mat-chip-listbox [tabIndex]="tabIndex" [selectable]="selectable">
+    <mat-chip-listbox [tabIndex]="tabIndex" [selectable]="selectable" [role]="role">
       <mat-chip-option *ngFor="let i of chips" (select)="chipSelect(i)"
         (deselect)="chipDeselect(i)">
         {{name}} {{i + 1}}
@@ -759,6 +766,7 @@ class StandardChipListbox {
   chipDeselect: (index?: number) => void = () => {};
   tabIndex: number = 0;
   chips = [0, 1, 2, 3, 4];
+  role: string | null = null;
 }
 
 @Component({

src/material-experimental/mdc-chips/chip-listbox.ts

@@ -99,11 +99,8 @@ export class MatChipListbox
    */
   _onChange: (value: any) => void = () => {};
 
-  /** The ARIA role applied to the chip listbox. */
   // TODO: MDC uses `grid` here
-  override get role(): string | null {
-    return this.empty ? null : 'listbox';
-  }
+  protected override _defaultRole = 'listbox';
 
   /** Whether the user should be allowed to select multiple chips. */
   @Input()

src/material-experimental/mdc-chips/chip-option.spec.ts

@@ -185,6 +185,17 @@ describe('MDC-based Option Chips', () => {
           .withContext('Expected chip ripples to be disabled.')
           .toBe(true);
       });
+
+      it('should have the correct role', () => {
+        expect(chipNativeElement.getAttribute('role')).toBe('presentation');
+      });
+
+      it('should be able to set a custom role', () => {
+        chipInstance.role = 'button';
+        fixture.detectChanges();
+
+        expect(chipNativeElement.getAttribute('role')).toBe('button');
+      });
     });
 
     describe('keyboard behavior', () => {

src/material-experimental/mdc-chips/chip-row.spec.ts

@@ -104,6 +104,17 @@ describe('MDC-based Row Chips', () => {
 
         expect(event.defaultPrevented).toBe(true);
       });
+
+      it('should have the correct role', () => {
+        expect(chipNativeElement.getAttribute('role')).toBe('row');
+      });
+
+      it('should be able to set a custom role', () => {
+        chipInstance.role = 'button';
+        fixture.detectChanges();
+
+        expect(chipNativeElement.getAttribute('role')).toBe('button');
+      });
     });
 
     describe('keyboard behavior', () => {

src/material-experimental/mdc-chips/chip-set.ts

@@ -88,6 +88,9 @@ export class MatChipSet
   /** Subject that emits when the component has been destroyed. */
   protected _destroyed = new Subject<void>();
 
+  /** Role to use if it hasn't been overwritten by the user. */
+  protected _defaultRole = 'presentation';
+
   /** Combined stream of all of the child chips' remove events. */
   get chipDestroyedChanges(): Observable<MatChipEvent> {
     return this._getChipStream(chip => chip.destroyed);
@@ -163,17 +166,17 @@ export class MatChipSet
   /** The ARIA role applied to the chip set. */
   @Input()
   get role(): string | null {
-    if (this._role) {
-      return this._role;
-    } else {
-      return this.empty ? null : 'presentation';
+    if (this._explicitRole) {
+      return this._explicitRole;
     }
+
+    return this.empty ? null : this._defaultRole;
   }
 
   set role(value: string | null) {
-    this._role = value;
+    this._explicitRole = value;
   }
-  private _role: string | null = null;
+  private _explicitRole: string | null = null;
 
   /** Whether any of the chips inside of this chip-set has focus. */
   get focused(): boolean {

src/material/chips/chip-list.spec.ts

@@ -191,6 +191,13 @@ describe('MatChipList', () => {
         expect(chipListNativeElement.hasAttribute('role')).toBe(false);
         expect(chipListNativeElement.hasAttribute('aria-required')).toBe(false);
       });
+
+      it('should be able to set a custom role', () => {
+        fixture.componentInstance.chipList.role = 'grid';
+        fixture.detectChanges();
+
+        expect(chipListNativeElement.getAttribute('role')).toBe('grid');
+      });
     });
 
     describe('focus behaviors', () => {
@@ -1725,9 +1732,9 @@ class FalsyValueChipList {
 @Component({
   template: `
     <mat-chip-list>
-        <mat-chip *ngFor="let food of foods" [value]="food.value" [selected]="food.selected">
-            {{ food.viewValue }}
-        </mat-chip>
+      <mat-chip *ngFor="let food of foods" [value]="food.value" [selected]="food.selected">
+        {{ food.viewValue }}
+      </mat-chip>
     </mat-chip-list>
   `,
 })
@@ -1738,6 +1745,7 @@ class SelectedChipList {
     {value: 2, viewValue: 'Pasta', selected: true},
   ];
   @ViewChildren(MatChip) chips: QueryList<MatChip>;
+  @ViewChild(MatChipList, {static: false}) chipList: MatChipList;
 }
 
 @Component({

src/material/chips/chip-list.ts

@@ -180,9 +180,18 @@ export class MatChipList
   }
 
   /** The ARIA role applied to the chip list. */
+  @Input()
   get role(): string | null {
+    if (this._explicitRole) {
+      return this._explicitRole;
+    }
+
     return this.empty ? null : 'listbox';
   }
+  set role(role: string | null) {
+    this._explicitRole = role;
+  }
+  private _explicitRole?: string | null;
 
   /**
    * Implemented as part of MatFormFieldControl.

src/material/chips/chip.spec.ts

@@ -73,6 +73,28 @@ describe('MatChip', () => {
 
       expect(chip.getAttribute('tabindex')).toBe('15');
     });
+
+    it('should have the correct role', () => {
+      fixture = TestBed.createComponent(BasicChip);
+      fixture.detectChanges();
+      chipDebugElement = fixture.debugElement.query(By.directive(MatChip))!;
+      chipNativeElement = chipDebugElement.nativeElement;
+
+      expect(chipNativeElement.getAttribute('role')).toBe('option');
+    });
+
+    it('should be able to set a custom role', () => {
+      fixture = TestBed.createComponent(BasicChip);
+      fixture.detectChanges();
+      chipDebugElement = fixture.debugElement.query(By.directive(MatChip))!;
+      chipInstance = chipDebugElement.injector.get<MatChip>(MatChip);
+      chipNativeElement = chipDebugElement.nativeElement;
+
+      chipInstance.role = 'gridcell';
+      fixture.detectChanges();
+
+      expect(chipNativeElement.getAttribute('role')).toBe('gridcell');
+    });
   });
 
   describe('MatChip', () => {