Ember can v2

addon/helpers/can.js

@@ -31,5 +31,11 @@ export default Helper.extend({
 
   _removeAbilityObserver() {
     this.removeObserver(`ability.${this.get('propertyName')}`, this, 'recompute');
+
+    let ability = this.get('ability')
+
+    if (ability) {
+      ability.destroy();
+    }
   }
 });

addon/services/can.js

@@ -2,6 +2,7 @@ import Service from '@ember/service';
 import { assert } from '@ember/debug';
 import { getOwner } from '@ember/application';
 import { assign } from '@ember/polyfills';
+import { run } from '@ember/runloop';
 
 import normalizeAbilityString from 'ember-can/utils/normalize';
 
@@ -10,16 +11,16 @@ export default Service.extend({
     return normalizeAbilityString(abilityString);
   },
 
+  abilityFor(abilityName, model, properties = {}) {
+    let Ability = getOwner(this).factoryFor(`ability:${abilityName}`);
 
-    return this.abilityFor(...arguments);
-  },
+    assert(`No ability type found for '${abilityName}'`, Ability);
 
-  abilityFor(abilityName, model, properties = {}) {
-    let ability = getOwner(this).lookup(`ability:${abilityName}`);
-    assert(`No ability type found for ${abilityName}`, ability);
+    if (typeof model != 'undefined') {
+      properties = assign({}, { model }, properties);
+    }
 
-    ability.setProperties(assign({}, { model }, properties));
-    return ability;
+    return Ability.create(properties);
   },
 
   can(abilityString, model, properties) {

tests/integration/helpers/can-test.js

@@ -23,20 +23,51 @@ module('Integration | Helper | can', function(hooks) {
   });
 
   test('it can receives model', async function(assert) {
-    assert.expect(2);
+    assert.expect(4);
 
     this.owner.register('ability:post', Ability.extend({
       canWrite: computed('model.write', function() {
         return this.get('model.write');
       }),
     }));
 
-    this.set('model', { write: false });
     await render(hbs`{{if (can "write post" model) "true" "false"}}`);
     assert.equal(this.element.textContent.trim(), 'false');
 
+    this.set('model', { write: false });
+    assert.equal(this.element.textContent.trim(), 'false');
+
     this.set('model', { write: true });
     assert.equal(this.element.textContent.trim(), 'true');
+
+    this.set('model', null);
+    assert.equal(this.element.textContent.trim(), 'false');
+  });
+
+  test('it works with default model', async function(assert) {
+    assert.expect(4);
+
+    this.owner.register('ability:post', Ability.extend({
+      model: computed(function() {
+        return { write: true }
+      }),
+
+      canWrite: computed('model.write', function() {
+        return this.get('model.write');
+      }),
+    }));
+
+    await render(hbs`{{if (can "write post" model) "true" "false"}}`);
+    assert.equal(this.element.textContent.trim(), 'true');
+
+    this.set('model', undefined);
+    assert.equal(this.element.textContent.trim(), 'true');
+
+    this.set('model', null);
+    assert.equal(this.element.textContent.trim(), 'false');
+
+    this.set('model', { write: false });
+    assert.equal(this.element.textContent.trim(), 'false');
   });
 
   test('it can receives properties', async function(assert) {

tests/unit/services/can-test.js

@@ -49,7 +49,7 @@ module('Unit | Service | can', function(hooks) {
       }),
     }));
 
-    assert.ok(service.can('touchThis in superModel', { yeah: true }));
+    assert.equal(service.can('touchThis in superModel', { yeah: true }), true);
   });
 
   test('cannot', function(assert) {
@@ -63,6 +63,6 @@ module('Unit | Service | can', function(hooks) {
       }),
     }));
 
-    assert.notOk(service.can('touchThis in superModel', { yeah: false }));
+    assert.equal(service.can('touchThis in superModel', { yeah: false }), false);
   });
 });