add support for array includes

README.md

@@ -28,6 +28,7 @@ lte      | `if (a <= b)`                                   | `{{if (lte a b)}}`
 is-array | `if (Ember.isArray(a))`                         | `{{if (is-array a)}}`   | Yes                             |
 is-empty | `if (Ember.isEmpty(a))`                         | `{{if (is-empty a)}}`   | No                              |
 is-equal | `if (Ember.isEqual(a, b))`                      | `{{if (is-equal a b)}}` | No                              |
+includes | `if (a.includes(b))`                            | `{{if (includes a b)}}` | No                              |
 
 <sup>
   * Unlike their JavaScript counterparts, these expressions do <em>not</em> short circuit.

addon/helpers/includes.js

@@ -0,0 +1,11 @@
+import { helper } from '@ember/component/helper';
+
+export function includes([haystack, pin]) {
+  if (!haystack || haystack.constructor.name !== 'Array') {
+    return false;
+  }
+
+  return haystack.includes(pin);
+}
+
+export default helper(includes);

app/helpers/includes.js

@@ -0,0 +1 @@
+export { default, includes } from 'ember-truth-helpers/helpers/includes';

tests/unit/helpers/includes-test.js

@@ -0,0 +1,63 @@
+import { run } from '@ember/runloop';
+import EmberObject from '@ember/object';
+import { module, test } from 'qunit';
+import { setupRenderingTest } from 'ember-qunit';
+import { render, find } from '@ember/test-helpers';
+import hbs from 'htmlbars-inline-precompile';
+
+module('helper:includes', function(hooks) {
+  setupRenderingTest(hooks);
+
+  test('first param is an array', async function(assert) {
+    const fakeContextObject = EmberObject.create({
+      valueA: [1, 2, 3, 4, 5]
+    });
+    this.set('contextChild', fakeContextObject);
+
+    await render(
+      hbs`[{{includes contextChild.valueA 5}}] [{{includes contextChild.valueA 6}}] [{{includes contextChild.valueA 9}}]`
+    );
+
+    assert.equal(find('*').textContent, '[true] [false] [false]', 'value should be "[true] [false] [false]"');
+
+    run(fakeContextObject, 'set', 'valueA', [1, 2, 3, 4, '5']);
+    assert.equal(find('*').textContent, '[false] [false] [false]', 'value should be "[false] [false] [false]"');
+
+    run(fakeContextObject, 'set', 'valueA', []);
+    assert.equal(find('*').textContent, '[false] [false] [false]', 'value should be "[false] [false] [false]"');
+  });
+
+  test('first param is not an array', async function(assert) {
+    const fakeContextObject = EmberObject.create({
+      valueA: null,
+      valueB: 'string',
+      valueC: 42,
+      valueD: {}
+    });
+    this.set('contextChild', fakeContextObject);
+
+    await render(
+      hbs`[{{includes contextChild.valueA 5}}] [{{includes contextChild.valueA 6}}] [{{includes contextChild.valueA 9}}]`
+    );
+
+    assert.equal(find('*').textContent, '[false] [false] [false]', 'value should be "[false] [false] [false]"');
+
+    await render(
+      hbs`[{{includes contextChild.valueB 'st'}}] [{{includes contextChild.valueB 6}}] [{{includes contextChild.valueB 9}}]`
+    );
+
+    assert.equal(find('*').textContent, '[false] [false] [false]', 'value should be "[false] [false] [false]"');
+
+    await render(
+      hbs`[{{includes contextChild.valueC 'st'}}] [{{includes contextChild.valueC 6}}] [{{includes contextChild.valueC 9}}]`
+    );
+
+    assert.equal(find('*').textContent, '[false] [false] [false]', 'value should be "[false] [false] [false]"');
+
+    await render(
+      hbs`[{{includes contextChild.valueD 'st'}}] [{{includes contextChild.valueD 6}}] [{{includes contextChild.valueD 9}}]`
+    );
+
+    assert.equal(find('*').textContent, '[false] [false] [false]', 'value should be "[false] [false] [false]"');
+  });
+});