fix(checkbox): Disable transitions when using mdc-checkbox-anim* classes

packages/mdc-checkbox/constants.js

@@ -15,18 +15,18 @@
  */
 
 const ROOT = 'mdc-checkbox';
-const ANIM = `${ROOT}--anim`;
 
 export const cssClasses = {
-  ROOT,
-  CHECKED: `${ROOT}--checked`,
-  INDETERMINATE: `${ROOT}--indeterminate`,
-  ANIM_UNCHECKED_CHECKED: `${ANIM}-unchecked-checked`,
-  ANIM_UNCHECKED_INDETERMINATE: `${ANIM}-unchecked-indeterminate`,
-  ANIM_CHECKED_UNCHECKED: `${ANIM}-checked-unchecked`,
-  ANIM_CHECKED_INDETERMINATE: `${ANIM}-checked-indeterminate`,
-  ANIM_INDETERMINATE_CHECKED: `${ANIM}-indeterminate-checked`,
-  ANIM_INDETERMINATE_UNCHECKED: `${ANIM}-indeterminate-unchecked`,
+  ROOT: 'mdc-checkbox',
+  UPGRADED: 'mdc-checkbox--upgraded',
+  CHECKED: 'mdc-checkbox--checked',
+  INDETERMINATE: 'mdc-checkbox--indeterminate',
+  ANIM_UNCHECKED_CHECKED: 'mdc-checkbox--anim-unchecked-checked',
+  ANIM_UNCHECKED_INDETERMINATE: 'mdc-checkbox--anim-unchecked-indeterminate',
+  ANIM_CHECKED_UNCHECKED: 'mdc-checkbox--anim-checked-unchecked',
+  ANIM_CHECKED_INDETERMINATE: 'mdc-checkbox--anim-checked-indeterminate',
+  ANIM_INDETERMINATE_CHECKED: 'mdc-checkbox--anim-indeterminate-checked',
+  ANIM_INDETERMINATE_UNCHECKED: 'mdc-checkbox--anim-indeterminate-unchecked',
 };
 
 export const strings = {

packages/mdc-checkbox/foundation.js

@@ -63,6 +63,7 @@ export default class MDCCheckboxFoundation extends MDCFoundation {
   }
 
   init() {
+    this.adapter_.addClass(cssClasses.UPGRADED);
     this.adapter_.registerChangeHandler(this.changeHandler_);
     this.installPropertyChangeHooks_();
   }

packages/mdc-checkbox/mdc-checkbox.scss

@@ -1,12 +1,12 @@
-// 
+//
 // Copyright 2016 Google Inc. All Rights Reserved.
-// 
+//
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
-// 
+//
 //      http://www.apache.org/licenses/LICENSE-2.0
-// 
+//
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -234,6 +234,19 @@ fieldset:disabled .mdc-checkbox__native-control,
   }
 }
 
+.mdc-checkbox--upgraded {
+  .mdc-checkbox__background,
+  .mdc-checkbox__checkmark,
+  .mdc-checkbox__checkmark__path,
+  .mdc-checkbox__mixedmark {
+    // Due to the myriad of selector combos used to properly style a CSS-only checkbox, all of
+    // which have varying selector precedence and make use of transitions, it is cleaner and more
+    // efficient here to simply use !important, since the mdc-checkbox--anim-* classes will take
+    // over from here.
+    transition: none !important;
+  }
+}
+
 .mdc-checkbox--anim {
   $_mdc-checkbox-indeterminate-change-duration: 500ms;
 

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

@@ -123,6 +123,14 @@ test('defaultAdapter returns a complete adapter implementation', (t) => {
   t.end();
 });
 
+test('#init adds the upgraded class to the root element', (t) => {
+  const {foundation, mockAdapter} = setupTest();
+
+  foundation.init();
+  t.doesNotThrow(() => td.verify(mockAdapter.addClass(cssClasses.UPGRADED)));
+  t.end();
+});
+
 test('#init calls adapter.registerChangeHandler() with a change handler function', (t) => {
   const {foundation, mockAdapter} = setupTest();
   const {isA} = td.matchers;
@@ -406,19 +414,21 @@ test('change handler triggers layout for changes within the same frame to correc
 
 test('change handler does not add animation classes when isAttachedToDOM() is falsy', (t) => {
   const {mockAdapter, change} = setupChangeHandlerTest();
+  const animClassArg = td.matchers.argThat((cls) => cls.indexOf('mdc-checkbox--anim') >= 0);
   td.when(mockAdapter.isAttachedToDOM()).thenReturn(false);
 
   change({checked: true, indeterminate: false});
-  t.doesNotThrow(() => td.verify(mockAdapter.addClass(td.matchers.anything()), {times: 0}));
+  t.doesNotThrow(() => td.verify(mockAdapter.addClass(animClassArg), {times: 0}));
 
   t.end();
 });
 
 test('change handler does not add animation classes for bogus changes (init -> unchecked)', (t) => {
   const {mockAdapter, change} = setupChangeHandlerTest();
+  const animClassArg = td.matchers.argThat((cls) => cls.indexOf('mdc-checkbox--anim') >= 0);
 
   change({checked: false, indeterminate: false});
-  t.doesNotThrow(() => td.verify(mockAdapter.addClass(td.matchers.anything()), {times: 0}));
+  t.doesNotThrow(() => td.verify(mockAdapter.addClass(animClassArg), {times: 0}));
   t.end();
 });