[FEATURE ember-views-component-block-info]

FEATURES.md

@@ -215,3 +215,80 @@ for a detailed explanation.
   ```
 
   Added in [#10274](https://github.com/emberjs/ember.js/pull/10274)
+
+* `ember-views-component-block-info`
+
+  Adds a couple utility methods to detect block/block param presence:
+
+  * `hasBlock`
+
+    Adds the ability to easily detect if a component was invoked with or
+    without a block.
+
+    Example (`hasBlock` will be `false`):
+
+    ```hbs
+    {{! templates/application.hbs }}
+
+    {{foo-bar}}
+
+    {{! templates/components/foo-bar.js }}
+    {{#if hasBlock}}
+      This will not be printed, because no block was provided
+    {{/if}}
+    ```
+
+    Example (`hasBlock` will be `true`):
+
+    ```hbs
+    {{! templates/application.hbs }}
+
+    {{#foo-bar}}
+      Hi!
+    {{/foo-bar}}
+
+    {{! templates/components/foo-bar.js }}
+    {{#if hasBlock}}
+      This will be printed because a block was provided
+      {{yield}}
+    {{/if}}
+    ```
+
+  * `hasBlockParams`
+
+  Adds the ability to easily detect if a component was invoked with block parameter
+  supplied.
+
+  Example (`hasBlockParams` will be `false`):
+
+  ```hbs
+  {{! templates/application.hbs }}
+
+  {{#foo-bar}}
+    Hi!.
+  {{/foo-bar}}
+
+  {{! templates/components/foo-bar.js }}
+  {{#if hasBlockParams}}
+    {{yield this}}
+    This will not be printed, because no block was provided
+  {{/if}}
+  ```
+
+  Example (`hasBlockParams` will be `true`):
+
+  ```hbs
+  {{! templates/application.hbs }}
+
+  {{#foo-bar as |foo|}}
+    Hi!
+  {{/foo-bar}}
+
+  {{! templates/components/foo-bar.js }}
+  {{#if hasBlockParams}}
+    {{yield this}}
+    This will be printed because a block was provided
+  {{/if}}
+  ```
+
+  Addd in [#10461](https://github.com/emberjs/ember.js/pull/10461)

features.json

@@ -18,7 +18,8 @@
     "ember-application-instance-initializers": null,
     "ember-application-initializer-context": null,
     "ember-router-willtransition": true,
-    "ember-application-visit": null
+    "ember-application-visit": null,
+    "ember-views-component-block-info": null
   },
   "debugStatements": [
     "Ember.warn",

packages/ember-htmlbars/tests/integration/component_invocation_test.js

@@ -84,3 +84,65 @@ QUnit.test('block with properties', function() {
 
   equal(jQuery('#qunit-fixture').text(), 'In layout - someProp: something here - In template');
 });
+
+if (Ember.FEATURES.isEnabled('ember-views-component-block-info')) {
+  QUnit.test('`Component.prototype.hasBlock` when block supplied', function() {
+    expect(1);
+
+    registry.register('template:components/with-block', compile('{{#if hasBlock}}{{yield}}{{else}}No Block!{{/if}}'));
+
+    view = EmberView.extend({
+      template: compile('{{#with-block}}In template{{/with-block}}'),
+      container: container
+    }).create();
+
+    runAppend(view);
+
+    equal(jQuery('#qunit-fixture').text(), 'In template');
+  });
+
+  QUnit.test('`Component.prototype.hasBlock` when no block supplied', function() {
+    expect(1);
+
+    registry.register('template:components/with-block', compile('{{#if hasBlock}}{{yield}}{{else}}No Block!{{/if}}'));
+
+    view = EmberView.extend({
+      template: compile('{{with-block}}'),
+      container: container
+    }).create();
+
+    runAppend(view);
+
+    equal(jQuery('#qunit-fixture').text(), 'No Block!');
+  });
+
+  QUnit.test('`Component.prototype.hasBlockParams` when block param supplied', function() {
+    expect(1);
+
+    registry.register('template:components/with-block', compile('{{#if hasBlockParams}}{{yield this}} - In Component{{else}}{{yield}} No Block!{{/if}}'));
+
+    view = EmberView.extend({
+      template: compile('{{#with-block as |something|}}In template{{/with-block}}'),
+      container: container
+    }).create();
+
+    runAppend(view);
+
+    equal(jQuery('#qunit-fixture').text(), 'In template - In Component');
+  });
+
+  QUnit.test('`Component.prototype.hasBlockParams` when no block param supplied', function() {
+    expect(1);
+
+    registry.register('template:components/with-block', compile('{{#if hasBlockParams}}{{yield this}}{{else}}{{yield}} No Block Param!{{/if}}'));
+
+    view = EmberView.extend({
+      template: compile('{{#with-block}}In block{{/with-block}}'),
+      container: container
+    }).create();
+
+    runAppend(view);
+
+    equal(jQuery('#qunit-fixture').text(), 'In block No Block Param!');
+  });
+}

packages/ember-views/lib/views/component.js

@@ -9,6 +9,7 @@ import { set } from "ember-metal/property_set";
 import isNone from 'ember-metal/is_none';
 
 import { computed } from "ember-metal/computed";
+import { bool } from "ember-metal/computed_macros";
 import defaultComponentLayout from "ember-htmlbars/templates/component";
 
 var a_slice = Array.prototype.slice;
@@ -324,4 +325,86 @@ var Component = View.extend(TargetActionSupport, ComponentTemplateDeprecation, {
   }
 });
 
+if (Ember.FEATURES.isEnabled('ember-views-component-block-info')) {
+  Component.reopen({
+    /**
+      Returns true when the component was invoked with a block template.
+
+     Example (`hasBlock` will be `false`):
+
+      ```hbs
+      {{! templates/application.hbs }}
+
+      {{foo-bar}}
+
+      {{! templates/components/foo-bar.js }}
+      {{#if hasBlock}}
+        This will not be printed, because no block was provided
+      {{/if}}
+      ```
+
+     Example (`hasBlock` will be `true`):
+
+      ```hbs
+      {{! templates/application.hbs }}
+
+      {{#foo-bar}}
+        Hi!
+      {{/foo-bar}}
+
+      {{! templates/components/foo-bar.js }}
+      {{#if hasBlock}}
+        This will be printed because a block was provided
+        {{yield}}
+      {{/if}}
+      ```
+      @public
+      @property hasBlock
+      @returns Boolean
+    */
+    hasBlock: bool('template'),
+
+    /**
+      Returns true when the component was invoked with a block parameter
+      supplied.
+
+      Example (`hasBlockParams` will be `false`):
+
+      ```hbs
+      {{! templates/application.hbs }}
+
+      {{#foo-bar}}
+        No block parameter.
+      {{/foo-bar}}
+
+      {{! templates/components/foo-bar.js }}
+      {{#if hasBlockParams}}
+        This will not be printed, because no block was provided
+        {{yield this}}
+      {{/if}}
+      ```
+
+      Example (`hasBlockParams` will be `true`):
+
+      ```hbs
+      {{! templates/application.hbs }}
+
+      {{#foo-bar as |foo|}}
+        Hi!
+      {{/foo-bar}}
+
+      {{! templates/components/foo-bar.js }}
+      {{#if hasBlockParams}}
+        This will be printed because a block was provided
+        {{yield this}}
+      {{/if}}
+      ```
+      @public
+      @property hasBlockParams
+      @returns Boolean
+    */
+    hasBlockParams: bool('template.blockParams')
+  });
+}
+
 export default Component;

packages/ember-views/tests/views/component_test.js

@@ -244,3 +244,24 @@ QUnit.test('component with target', function() {
 
   appComponent.send('foo', 'baz');
 });
+
+if (Ember.FEATURES.isEnabled('ember-views-component-has-block')) {
+  QUnit.test('component with a template will report hasBlock: true', function() {
+    expect(1);
+
+    var appComponent = Component.create({
+      template: 'some-thing-yolo'
+    });
+
+    equal(get(appComponent, 'hasBlock'), true);
+  });
+
+  QUnit.test('component without a template will report hasBlock: false', function() {
+    expect(1);
+
+    var appComponent = Component.create({
+    });
+
+    equal(get(appComponent, 'hasBlock'), false);
+  });
+}