fix(checkbox): Implement component/adapter APIs to sync aria-checked

packages/mdc-checkbox/foundation.js

@@ -49,8 +49,8 @@ class MDCCheckboxFoundation extends MDCFoundation {
     return /** @type {!MDCCheckboxAdapter} */ ({
       addClass: (/* className: string */) => {},
       removeClass: (/* className: string */) => {},
-      setNativeControlAttr: () => {},
-      removeNativeControlAttr: () => {},
+      setNativeControlAttr: (/* attr: string, value: string */) => {},
+      removeNativeControlAttr: (/* attr: string */) => {},
       registerAnimationEndHandler: (/* handler: EventListener */) => {},
       deregisterAnimationEndHandler: (/* handler: EventListener */) => {},
       registerChangeHandler: (/* handler: EventListener */) => {},
@@ -82,6 +82,7 @@ class MDCCheckboxFoundation extends MDCFoundation {
 
   init() {
     this.currentCheckState_ = this.determineCheckState_(this.getNativeControl_());
+    this.updateAriaChecked_();
     this.adapter_.addClass(cssClasses.UPGRADED);
     this.adapter_.registerChangeHandler(this.changeHandler_);
     this.installPropertyChangeHooks_();
@@ -205,13 +206,7 @@ class MDCCheckboxFoundation extends MDCFoundation {
       return;
     }
 
-    // Ensure aria-checked is set to mixed if checkbox is in indeterminate state.
-    if (this.isIndeterminate()) {
-      this.adapter_.setNativeControlAttr(
-        strings.ARIA_CHECKED_ATTR, strings.ARIA_CHECKED_INDETERMINATE_VALUE);
-    } else {
-      this.adapter_.removeNativeControlAttr(strings.ARIA_CHECKED_ATTR);
-    }
+    this.updateAriaChecked_();
 
     // Check to ensure that there isn't a previously existing animation class, in case for example
     // the user interacted with the checkbox before the animation was finished.
@@ -288,6 +283,16 @@ class MDCCheckboxFoundation extends MDCFoundation {
     }
   }
 
+  updateAriaChecked_() {
+    // Ensure aria-checked is set to mixed if checkbox is in indeterminate state.
+    if (this.isIndeterminate()) {
+      this.adapter_.setNativeControlAttr(
+        strings.ARIA_CHECKED_ATTR, strings.ARIA_CHECKED_INDETERMINATE_VALUE);
+    } else {
+      this.adapter_.removeNativeControlAttr(strings.ARIA_CHECKED_ATTR);
+    }
+  }
+
   /**
    * @return {!MDCSelectionControlState}
    * @private

packages/mdc-checkbox/index.js

@@ -73,6 +73,8 @@ class MDCCheckbox extends MDCComponent {
     return new MDCCheckboxFoundation({
       addClass: (className) => this.root_.classList.add(className),
       removeClass: (className) => this.root_.classList.remove(className),
+      setNativeControlAttr: (attr, value) => this.nativeCb_.setAttribute(attr, value),
+      removeNativeControlAttr: (attr) => this.nativeCb_.removeAttribute(attr),
       registerAnimationEndHandler:
         (handler) => this.root_.addEventListener(getCorrectEventName(window, 'animationend'), handler),
       deregisterAnimationEndHandler:

test/unit/mdc-checkbox/foundation.test.js

@@ -123,6 +123,14 @@ test('#init adds the upgraded class to the root element', () => {
   td.verify(mockAdapter.addClass(cssClasses.UPGRADED));
 });
 
+test('#init adds aria-checked="mixed" if checkbox is initially indeterminate', () => {
+  const {foundation, mockAdapter, nativeControl} = setupTest();
+  nativeControl.indeterminate = true;
+
+  foundation.init();
+  td.verify(mockAdapter.setNativeControlAttr('aria-checked', strings.ARIA_CHECKED_INDETERMINATE_VALUE));
+});
+
 test('#init calls adapter.registerChangeHandler() with a change handler function', () => {
   const {foundation, mockAdapter} = setupTest();
   const {isA} = td.matchers;
@@ -216,6 +224,20 @@ test('#setIndeterminate updates the value of nativeControl.indeterminate', () =>
   assert.isNotOk(nativeControl.indeterminate);
 });
 
+test('#setIndeterminate adds aria-checked="mixed" when indeterminate is true', () => {
+  const {foundation, mockAdapter} = setupTest();
+  foundation.init();
+  foundation.setIndeterminate(true);
+  td.verify(mockAdapter.setNativeControlAttr('aria-checked', strings.ARIA_CHECKED_INDETERMINATE_VALUE));
+});
+
+test('#setIndeterminate removes aria-checked when indeterminate is false', () => {
+  const {foundation, mockAdapter} = setupTest();
+  foundation.init();
+  foundation.setIndeterminate(false);
+  td.verify(mockAdapter.removeNativeControlAttr('aria-checked'));
+});
+
 test('#setIndeterminate works when no native control is returned', () => {
   const {foundation, mockAdapter} = setupTest();
   td.when(mockAdapter.getNativeControl()).thenReturn(null);

test/unit/mdc-checkbox/mdc-checkbox.test.js

@@ -51,8 +51,9 @@ function getFixture() {
 
 function setupTest() {
   const root = getFixture();
+  const cb = root.querySelector(strings.NATIVE_CONTROL_SELECTOR);
   const component = new MDCCheckbox(root);
-  return {root, component};
+  return {root, cb, component};
 }
 
 suite('MDCCheckbox');
@@ -100,32 +101,28 @@ test('attachTo initializes and returns a MDCCheckbox instance', () => {
 });
 
 test('get/set checked updates the checked property on the native checkbox element', () => {
-  const {root, component} = setupTest();
-  const cb = root.querySelector(strings.NATIVE_CONTROL_SELECTOR);
+  const {cb, component} = setupTest();
   component.checked = true;
   assert.isOk(cb.checked);
   assert.equal(component.checked, cb.checked);
 });
 
 test('get/set indeterminate updates the indeterminate property on the native checkbox element', () => {
-  const {root, component} = setupTest();
-  const cb = root.querySelector(strings.NATIVE_CONTROL_SELECTOR);
+  const {cb, component} = setupTest();
   component.indeterminate = true;
   assert.isOk(cb.indeterminate);
   assert.equal(component.indeterminate, cb.indeterminate);
 });
 
 test('get/set disabled updates the indeterminate property on the native checkbox element', () => {
-  const {root, component} = setupTest();
-  const cb = root.querySelector(strings.NATIVE_CONTROL_SELECTOR);
+  const {cb, component} = setupTest();
   component.disabled = true;
   assert.isOk(cb.disabled);
   assert.equal(component.disabled, cb.disabled);
 });
 
 test('get/set value updates the value of the native checkbox element', () => {
-  const {root, component} = setupTest();
-  const cb = root.querySelector(strings.NATIVE_CONTROL_SELECTOR);
+  const {cb, component} = setupTest();
   component.value = 'new value';
   assert.equal(cb.value, 'new value');
   assert.equal(component.value, cb.value);
@@ -149,6 +146,19 @@ test('adapter#removeClass removes a class from the root element', () => {
   assert.isNotOk(root.classList.contains('foo'));
 });
 
+test('adapter#setNativeControlAttr sets an attribute on the input element', () => {
+  const {cb, component} = setupTest();
+  component.getDefaultFoundation().adapter_.setNativeControlAttr('aria-checked', 'mixed');
+  assert.equal(cb.getAttribute('aria-checked'), 'mixed');
+});
+
+test('adapter#removeNativeControlAttr removes an attribute from the input element', () => {
+  const {cb, component} = setupTest();
+  cb.setAttribute('aria-checked', 'mixed');
+  component.getDefaultFoundation().adapter_.removeNativeControlAttr('aria-checked');
+  assert.isFalse(cb.hasAttribute('aria-checked'));
+});
+
 test('adapter#registerAnimationEndHandler adds an animation end event listener on the root element', () => {
   const {root, component} = setupTest();
   const handler = td.func('animationEndHandler');