fix(radio): take default tabindex value from attribute (#20453)

This is something that we have everywhere where we deal with `tabindex`, but it was missing on the radio button. Adds some logic that will take the initial `tabindex` value from the attribute through DI.

(cherry picked from commit 2c83b40)

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

@@ -794,6 +794,16 @@ describe('MDC-based MatRadio', () => {
       expect(radioButtonEl.getAttribute('tabindex')).toBe('-1');
     });
 
+    it('should forward a pre-defined tabindex to the underlying input', () => {
+      const predefinedFixture = TestBed.createComponent(RadioButtonWithPredefinedTabindex);
+      predefinedFixture.detectChanges();
+
+      const radioButtonInput = predefinedFixture.debugElement
+        .query(By.css('.mat-mdc-radio-button input'))!.nativeElement as HTMLInputElement;
+
+      expect(radioButtonInput.getAttribute('tabindex')).toBe('5');
+    });
+
     it('should remove the aria attributes from the host element', () => {
       const predefinedFixture = TestBed.createComponent(RadioButtonWithPredefinedAriaAttributes);
       predefinedFixture.detectChanges();
@@ -1016,7 +1026,7 @@ class TranscludingWrapper {}
 
 
 @Component({
-  template: `<mat-radio-button tabindex="0"></mat-radio-button>`
+  template: `<mat-radio-button tabindex="5"></mat-radio-button>`
 })
 class RadioButtonWithPredefinedTabindex {}
 

src/material-experimental/mdc-radio/radio.ts

@@ -8,6 +8,7 @@
 
 import {
   AfterViewInit,
+  Attribute,
   ChangeDetectionStrategy,
   ChangeDetectorRef,
   Component,
@@ -136,9 +137,10 @@ export class MatRadioButton extends _MatRadioButtonBase implements AfterViewInit
               _radioDispatcher: UniqueSelectionDispatcher,
               @Optional() @Inject(ANIMATION_MODULE_TYPE) _animationMode?: string,
               @Optional() @Inject(MAT_RADIO_DEFAULT_OPTIONS)
-              _providerOverride?: MatRadioDefaultOptions) {
+              _providerOverride?: MatRadioDefaultOptions,
+              @Attribute('tabindex') tabIndex?: string) {
     super(radioGroup, elementRef, _changeDetector, _focusMonitor,
-        _radioDispatcher, _animationMode, _providerOverride);
+        _radioDispatcher, _animationMode, _providerOverride, tabIndex);
   }
 
   ngAfterViewInit() {

src/material/radio/radio.spec.ts

@@ -787,6 +787,16 @@ describe('MatRadio', () => {
       expect(radioButtonEl.getAttribute('tabindex')).toBe('-1');
     });
 
+    it('should forward a pre-defined tabindex to the underlying input', () => {
+      const predefinedFixture = TestBed.createComponent(RadioButtonWithPredefinedTabindex);
+      predefinedFixture.detectChanges();
+
+      const radioButtonInput = predefinedFixture.debugElement
+        .query(By.css('.mat-radio-button input'))!.nativeElement as HTMLInputElement;
+
+      expect(radioButtonInput.getAttribute('tabindex')).toBe('5');
+    });
+
     it('should remove the aria attributes from the host element', () => {
       const predefinedFixture = TestBed.createComponent(RadioButtonWithPredefinedAriaAttributes);
       predefinedFixture.detectChanges();
@@ -999,7 +1009,7 @@ class TranscludingWrapper {}
 
 
 @Component({
-  template: `<mat-radio-button tabindex="0"></mat-radio-button>`
+  template: `<mat-radio-button tabindex="5"></mat-radio-button>`
 })
 class RadioButtonWithPredefinedTabindex {}
 

src/material/radio/radio.ts

@@ -7,11 +7,17 @@
  */
 
 import {FocusMonitor} from '@angular/cdk/a11y';
-import {BooleanInput, coerceBooleanProperty, NumberInput} from '@angular/cdk/coercion';
+import {
+  BooleanInput,
+  coerceBooleanProperty,
+  coerceNumberProperty,
+  NumberInput,
+} from '@angular/cdk/coercion';
 import {UniqueSelectionDispatcher} from '@angular/cdk/collections';
 import {
   AfterContentInit,
   AfterViewInit,
+  Attribute,
   ChangeDetectionStrategy,
   ChangeDetectorRef,
   Component,
@@ -489,13 +495,18 @@ export abstract class _MatRadioButtonBase extends _MatRadioButtonMixinBase imple
               private _focusMonitor: FocusMonitor,
               private _radioDispatcher: UniqueSelectionDispatcher,
               public _animationMode?: string,
-              private _providerOverride?: MatRadioDefaultOptions) {
+              private _providerOverride?: MatRadioDefaultOptions,
+              tabIndex?: string) {
     super(elementRef);
 
     // Assertions. Ideally these should be stripped out by the compiler.
     // TODO(jelbourn): Assert that there's no name binding AND a parent radio group.
     this.radioGroup = radioGroup;
 
+    if (tabIndex) {
+      this.tabIndex = coerceNumberProperty(tabIndex, 0);
+    }
+
     this._removeUniqueSelectionListener =
       _radioDispatcher.listen((id: string, name: string) => {
         if (id !== this.id && name === this.name) {
@@ -641,8 +652,9 @@ export class MatRadioButton extends _MatRadioButtonBase {
               radioDispatcher: UniqueSelectionDispatcher,
               @Optional() @Inject(ANIMATION_MODULE_TYPE) animationMode?: string,
                 @Optional() @Inject(MAT_RADIO_DEFAULT_OPTIONS)
-                  providerOverride?: MatRadioDefaultOptions) {
+                  providerOverride?: MatRadioDefaultOptions,
+              @Attribute('tabindex') tabIndex?: string) {
     super(radioGroup, elementRef, changeDetector, focusMonitor, radioDispatcher,
-          animationMode, providerOverride);
+          animationMode, providerOverride, tabIndex);
   }
 }

tools/public_api_guard/material/radio.d.ts

@@ -22,7 +22,7 @@ export declare abstract class _MatRadioButtonBase extends _MatRadioButtonMixinBa
     set required(value: boolean);
     get value(): any;
     set value(value: any);
-    constructor(radioGroup: _MatRadioGroupBase<_MatRadioButtonBase>, elementRef: ElementRef, _changeDetector: ChangeDetectorRef, _focusMonitor: FocusMonitor, _radioDispatcher: UniqueSelectionDispatcher, _animationMode?: string | undefined, _providerOverride?: MatRadioDefaultOptions | undefined);
+    constructor(radioGroup: _MatRadioGroupBase<_MatRadioButtonBase>, elementRef: ElementRef, _changeDetector: ChangeDetectorRef, _focusMonitor: FocusMonitor, _radioDispatcher: UniqueSelectionDispatcher, _animationMode?: string | undefined, _providerOverride?: MatRadioDefaultOptions | undefined, tabIndex?: string);
     _isRippleDisabled(): boolean;
     _markForCheck(): void;
     _onInputChange(event: Event): void;
@@ -84,9 +84,9 @@ export declare const MAT_RADIO_GROUP: InjectionToken<_MatRadioGroupBase<_MatRadi
 export declare const MAT_RADIO_GROUP_CONTROL_VALUE_ACCESSOR: any;
 
 export declare class MatRadioButton extends _MatRadioButtonBase {
-    constructor(radioGroup: MatRadioGroup, elementRef: ElementRef, changeDetector: ChangeDetectorRef, focusMonitor: FocusMonitor, radioDispatcher: UniqueSelectionDispatcher, animationMode?: string, providerOverride?: MatRadioDefaultOptions);
+    constructor(radioGroup: MatRadioGroup, elementRef: ElementRef, changeDetector: ChangeDetectorRef, focusMonitor: FocusMonitor, radioDispatcher: UniqueSelectionDispatcher, animationMode?: string, providerOverride?: MatRadioDefaultOptions, tabIndex?: string);
     static ɵcmp: i0.ɵɵComponentDefWithMeta<MatRadioButton, "mat-radio-button", ["matRadioButton"], { "disableRipple": "disableRipple"; "tabIndex": "tabIndex"; }, {}, never, ["*"]>;
-    static ɵfac: i0.ɵɵFactoryDef<MatRadioButton, [{ optional: true; }, null, null, null, null, { optional: true; }, { optional: true; }]>;
+    static ɵfac: i0.ɵɵFactoryDef<MatRadioButton, [{ optional: true; }, null, null, null, null, { optional: true; }, { optional: true; }, { attribute: "tabindex"; }]>;
 }
 
 export declare class MatRadioChange {