Merge pull request #17710 from emberjs/bugfix/allow-accessors-in-mixins

[BUGFIX beta] Allow accessors in mixins

packages/@ember/-internals/metal/lib/mixin.ts

@@ -5,6 +5,7 @@ import { Meta, meta as metaFor, peekMeta } from '@ember/-internals/meta';
 import {
   getListeners,
   getObservers,
+  getOwnPropertyDescriptors,
   guidFor,
   makeArray,
   NAME_KEY,
@@ -22,7 +23,7 @@ import {
   ComputedPropertyGetter,
   ComputedPropertySetter,
 } from './computed';
-import { makeComputedDecorator } from './decorator';
+import { makeComputedDecorator, nativeDescDecorator } from './decorator';
 import {
   descriptorForDecorator,
   descriptorForProperty,
@@ -50,6 +51,36 @@ function isMethod(obj: any): boolean {
   );
 }
 
+function isAccessor(desc: PropertyDescriptor) {
+  return typeof desc.get === 'function' || typeof desc.set === 'function';
+}
+
+function extractAccessors(properties: { [key: string]: any } | undefined) {
+  if (properties !== undefined) {
+    let descriptors = getOwnPropertyDescriptors(properties);
+    let keys = Object.keys(descriptors);
+    let hasAccessors = keys.some(key => isAccessor(descriptors[key]));
+
+    if (hasAccessors) {
+      let extracted = {};
+
+      keys.forEach(key => {
+        let descriptor = descriptors[key];
+
+        if (isAccessor(descriptor)) {
+          extracted[key] = nativeDescDecorator(descriptor);
+        } else {
+          extracted[key] = properties[key];
+        }
+      });
+
+      return extracted;
+    }
+  }
+
+  return properties;
+}
+
 const CONTINUE: MixinLike = {};
 
 function mixinProperties<T extends MixinLike>(mixinsMeta: Meta, mixin: T): MixinLike {
@@ -550,7 +581,7 @@ export default class Mixin {
   _without: any[] | undefined;
 
   constructor(mixins: Mixin[] | undefined, properties?: { [key: string]: any }) {
-    this.properties = properties;
+    this.properties = extractAccessors(properties);
     this.mixins = buildMixinsArray(mixins);
     this.ownerConstructor = undefined;
     this._without = undefined;

packages/@ember/-internals/metal/tests/mixin/accessor_test.js

@@ -0,0 +1,38 @@
+import { Mixin } from '../..';
+import { moduleFor, AbstractTestCase } from 'internal-test-helpers';
+
+moduleFor(
+  'Mixin Accessors',
+  class extends AbstractTestCase {
+    ['@test works with getters'](assert) {
+      let count = 0;
+
+      let MixinA = Mixin.create({
+        get prop() {
+          return count++;
+        },
+      });
+
+      let obj = {};
+      MixinA.apply(obj);
+
+      assert.equal(obj.prop, 0, 'getter defined correctly');
+      assert.equal(obj.prop, 1, 'getter defined correctly');
+    }
+
+    ['@test works with setters'](assert) {
+      let MixinA = Mixin.create({
+        set prop(value) {
+          this._prop = value + 1;
+        },
+      });
+
+      let obj = {};
+      MixinA.apply(obj);
+
+      obj.prop = 0;
+
+      assert.equal(obj._prop, 1, 'setter defined correctly');
+    }
+  }
+);

packages/@ember/-internals/utils/index.ts

@@ -10,6 +10,7 @@
 */
 export { default as symbol, isInternalSymbol } from './lib/symbol';
 export { default as dictionary } from './lib/dictionary';
+export { default as getOwnPropertyDescriptors } from './lib/get-own-property-descriptors';
 export { uuid, GUID_KEY, generateGuid, guidFor } from './lib/guid';
 export { default as intern } from './lib/intern';
 export {

packages/@ember/-internals/utils/lib/get-own-property-descriptors.ts

@@ -0,0 +1,17 @@
+let getOwnPropertyDescriptors: (obj: { [x: string]: any }) => { [x: string]: PropertyDescriptor };
+
+if (Object.getOwnPropertyDescriptors !== undefined) {
+  getOwnPropertyDescriptors = Object.getOwnPropertyDescriptors;
+} else {
+  getOwnPropertyDescriptors = function(obj: object) {
+    let descriptors = {};
+
+    Object.keys(obj).forEach(key => {
+      descriptors[key] = Object.getOwnPropertyDescriptor(obj, key);
+    });
+
+    return descriptors;
+  };
+}
+
+export default getOwnPropertyDescriptors;