fix(material/stepper): Adjust aria tab-related roles to fix violations

Author: adolgachev

src/material/stepper/step-header.ts

@@ -36,7 +36,7 @@ import {_CdkPrivateStyleLoader, _VisuallyHiddenLoader} from '@angular/cdk/privat
     'class': 'mat-step-header',
     '[class.mat-step-header-empty-label]': '_hasEmptyLabel()',
     '[class]': '"mat-" + (color || "primary")',
-    'role': 'tab',
+    'role': '', // ignore cdk role in favor of setting appropriately in html
   },
   encapsulation: ViewEncapsulation.None,
   changeDetection: ChangeDetectionStrategy.OnPush,

src/material/stepper/stepper.html

@@ -11,7 +11,10 @@
 @switch (orientation) {
   @case ('horizontal') {
     <div class="mat-horizontal-stepper-wrapper">
-      <div class="mat-horizontal-stepper-header-container">
+      <div 
+        aria-orientation="horizontal"
+        class="mat-horizontal-stepper-header-container" 
+        role="tablist">
         @for (step of steps; track step) {
           <ng-container
             [ngTemplateOutlet]="stepTemplate"
@@ -40,28 +43,38 @@
   }
 
   @case ('vertical') {
-    @for (step of steps; track step) {
-      <div class="mat-step">
-        <ng-container
-          [ngTemplateOutlet]="stepTemplate"
-          [ngTemplateOutletContext]="{step}"/>
-        <div
-          #animatedContainer
-          class="mat-vertical-content-container"
-          [class.mat-stepper-vertical-line]="!$last"
-          [class.mat-vertical-content-container-active]="selectedIndex === $index"
-          [attr.inert]="selectedIndex === $index ? null : ''">
-          <div class="mat-vertical-stepper-content"
-            role="tabpanel"
-            [id]="_getStepContentId($index)"
-            [attr.aria-labelledby]="_getStepLabelId($index)">
-            <div class="mat-vertical-content">
-              <ng-container [ngTemplateOutlet]="step.content"/>
+    <div 
+      aria-orientation="vertical"
+      class="mat-vertical-stepper-wrapper" 
+      role="tablist">
+      @for (step of steps; track step) {
+        <div 
+          class="mat-step" 
+          role="tab"    
+          [attr.aria-posinset]="step.index() + 1"
+          [attr.aria-setsize]="steps.length"
+          [attr.aria-selected]="step.isSelected()"
+        >
+          <ng-container
+            [ngTemplateOutlet]="stepTemplate"
+            [ngTemplateOutletContext]="{step}"/>
+          <div
+            #animatedContainer
+            class="mat-vertical-content-container"
+            [class.mat-stepper-vertical-line]="!$last"
+            [class.mat-vertical-content-container-active]="selectedIndex === $index"
+            [attr.inert]="selectedIndex === $index ? null : ''">
+            <div class="mat-vertical-stepper-content"
+              [id]="_getStepContentId($index)"
+              [attr.aria-labelledby]="_getStepLabelId($index)">
+              <div class="mat-vertical-content">
+                <ng-container [ngTemplateOutlet]="step.content"/>
+              </div>
             </div>
           </div>
         </div>
-      </div>
-    }
+      }
+    </div>
   }
 }
 
@@ -74,10 +87,11 @@
     (keydown)="_onKeydown($event)"
     [tabIndex]="_getFocusIndex() === step.index() ? 0 : -1"
     [id]="_getStepLabelId(step.index())"
-    [attr.aria-posinset]="step.index() + 1"
-    [attr.aria-setsize]="steps.length"
+    [attr.role]="orientation === 'horizontal' ? 'tab' : null"
+    [attr.aria-posinset]="orientation === 'horizontal' ? step.index() + 1 : null"
+    [attr.aria-setsize]="orientation === 'horizontal' ? steps.length : null"
+    [attr.aria-selected]="orientation === 'horizontal' ? step.isSelected() : null"
     [attr.aria-controls]="_getStepContentId(step.index())"
-    [attr.aria-selected]="step.isSelected()"
     [attr.aria-label]="step.ariaLabel || null"
     [attr.aria-labelledby]="(!step.ariaLabel && step.ariaLabelledby) ? step.ariaLabelledby : null"
     [attr.aria-disabled]="step.isNavigable() ? null : true"

src/material/stepper/stepper.spec.ts

@@ -114,11 +114,6 @@ describe('MatStepper', () => {
       expect(stepper.selected instanceof MatStep).toBe(true);
     });
 
-    it('should set the "tablist" role on stepper', () => {
-      const stepperEl = fixture.debugElement.query(By.css('mat-stepper'))!.nativeElement;
-      expect(stepperEl.getAttribute('role')).toBe('tablist');
-    });
-
     it('should display the correct label', () => {
       let selectedLabel = fixture.nativeElement.querySelector('[aria-selected="true"]');
       expect(selectedLabel.textContent).toMatch('Step 1');
@@ -344,7 +339,7 @@ describe('MatStepper', () => {
 
     it('should set the correct aria-posinset and aria-setsize', () => {
       const headers = Array.from<HTMLElement>(
-        fixture.nativeElement.querySelectorAll('.mat-step-header'),
+        fixture.nativeElement.querySelectorAll('[role="tab"]'),
       );
 
       expect(headers.map(header => header.getAttribute('aria-posinset'))).toEqual(['1', '2', '3']);
@@ -941,7 +936,7 @@ describe('MatStepper', () => {
       const fixture = createComponent(SimpleMatVerticalStepperApp);
       fixture.detectChanges();
 
-      const stepperEl = fixture.debugElement.query(By.css('mat-stepper'))!.nativeElement;
+      const stepperEl = fixture.debugElement.query(By.css('[role="tablist"]'))!.nativeElement;
       expect(stepperEl.getAttribute('aria-orientation')).toBe('vertical');
     });
 
@@ -1045,7 +1040,7 @@ describe('MatStepper', () => {
       const fixture = createComponent(SimpleMatHorizontalStepperApp);
       fixture.detectChanges();
 
-      const stepperEl = fixture.debugElement.query(By.css('mat-stepper'))!.nativeElement;
+      const stepperEl = fixture.debugElement.query(By.css('[role="tablist"]'))!.nativeElement;
       expect(stepperEl.getAttribute('aria-orientation')).toBe('horizontal');
     });
 

src/material/stepper/stepper.ts

@@ -130,8 +130,6 @@ export class MatStep extends CdkStep implements ErrorStateMatcher, AfterContentI
     '[class.mat-stepper-header-position-bottom]': 'headerPosition === "bottom"',
     '[class.mat-stepper-animating]': '_isAnimating()',
     '[style.--mat-stepper-animation-duration]': '_getAnimationDuration()',
-    '[attr.aria-orientation]': 'orientation',
-    'role': 'tablist',
   },
   providers: [{provide: CdkStepper, useExisting: MatStepper}],
   encapsulation: ViewEncapsulation.None,