Failing test for {{component}} keyword teardown.

packages/ember-htmlbars/lib/keywords/component.js

@@ -7,6 +7,10 @@ export default {
   },
 
   render(morph, ...rest) {
+    if (morph.state.manager) {
+      morph.state.manager.destroy();
+    }
+
     // Force the component hook to treat this as a first-time render,
     // because normal components (`<foo-bar>`) cannot change at runtime,
     // but the `{{component}}` helper can.

packages/ember-htmlbars/lib/keywords/view.js

@@ -70,6 +70,11 @@ export default {
       options.createOptions._targetObject = node.state.targetObject;
     }
 
+    if (state.manager) {
+      state.manager.destroy();
+      state.manager = null;
+    }
+
     var nodeManager = ViewNodeManager.create(node, env, hash, options, parentView, null, scope, template);
     state.manager = nodeManager;
 

packages/ember-htmlbars/lib/node-managers/component-node-manager.js

@@ -264,6 +264,15 @@ ComponentNodeManager.prototype.rerender = function(_env, attrs, visitor) {
   }, this);
 };
 
+ComponentNodeManager.prototype.destroy = function() {
+  let component = this.component;
+
+  // Clear component's render node. Normally this gets cleared
+  // during view destruction, but in this case we're re-assigning the
+  // node to a different view and it will get cleaned up automatically.
+  component._renderNode = null;
+  component.destroy();
+};
 
 export function createComponent(_component, isAngleBracket, _props, renderNode, env, attrs = {}) {
   let props = assign({}, _props);

packages/ember-htmlbars/lib/node-managers/view-node-manager.js

@@ -149,6 +149,10 @@ ViewNodeManager.prototype.rerender = function(env, attrs, visitor) {
   }, this);
 };
 
+ViewNodeManager.prototype.destroy = function() {
+  this.component.destroy();
+};
+
 function getTemplate(componentOrView) {
   return componentOrView.isComponent ? get(componentOrView, '_template') : get(componentOrView, 'template');
 }
@@ -191,6 +195,7 @@ export function createOrUpdateComponent(component, options, createOptions, rende
   }
 
   component._renderNode = renderNode;
+
   renderNode.emberView = component;
   return component;
 }

packages/ember-htmlbars/tests/helpers/component_test.js

@@ -49,6 +49,54 @@ if (isEnabled('ember-htmlbars-component-helper')) {
     equal(view.$().text(), 'yummy Loisaida arepas!', 'component was updated and re-rendered');
   });
 
+  QUnit.test("component helper destroys underlying component when it is swapped out", function() {
+    var currentComponent;
+    var destroyCalls = 0;
+    registry.register('component:foo-bar', Component.extend({
+      init() {
+        this._super(...arguments);
+        currentComponent = 'foo-bar';
+      },
+      willDestroy() {
+        destroyCalls++;
+      }
+    }));
+    registry.register('component:baz-qux', Component.extend({
+      init() {
+        this._super(...arguments);
+        currentComponent = 'baz-qux';
+      },
+      willDestroy() {
+        destroyCalls++;
+      }
+    }));
+
+    view = EmberView.create({
+      container: container,
+      dynamicComponent: 'foo-bar',
+      template: compile('{{component view.dynamicComponent}}')
+    });
+
+    runAppend(view);
+
+    equal(currentComponent, 'foo-bar', 'precond - instantiates the proper component');
+    equal(destroyCalls, 0, 'precond - nothing destroyed yet');
+
+    Ember.run(function() {
+      set(view, "dynamicComponent", 'baz-qux');
+    });
+
+    equal(currentComponent, 'baz-qux', 'changing bound value instantiates the proper component');
+    equal(destroyCalls, 1, 'prior component should be destroyed');
+
+    Ember.run(function() {
+      set(view, "dynamicComponent", 'foo-bar');
+    });
+
+    equal(currentComponent, 'foo-bar', 'changing bound value instantiates the proper component');
+    equal(destroyCalls, 2, 'prior components destroyed');
+  });
+
   QUnit.test("component helper with actions", function() {
     registry.register('template:components/foo-bar', compile('yippie! {{yield}}'));
     registry.register('component:foo-bar', Ember.Component.extend({