diff --git a/spec/javascript/components/emoji_index.test.js b/spec/javascript/components/emoji_index.test.js
new file mode 100644
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+++ b/spec/javascript/components/emoji_index.test.js
@@ -0,0 +1,81 @@
+import { expect } from 'chai';
+import { search } from '../../../app/javascript/mastodon/emoji_index_light';
+import { emojiIndex } from 'emoji-mart';
+import { pick } from 'lodash';
+
+const trimEmojis = emoji => pick(emoji, ['id', 'unified', 'native', 'custom']);
+
+// hack to fix https://github.com/chaijs/type-detect/issues/98
+// see: https://github.com/chaijs/type-detect/issues/98#issuecomment-325010785
+import jsdom from 'jsdom';
+global.window = new jsdom.JSDOM().window;
+global.document = window.document;
+global.HTMLElement = window.HTMLElement;
+
+describe('emoji_index', () => {
+
+  it('should give same result for emoji_index_light and emoji-mart', () => {
+    let expected = [{
+      id: 'pineapple',
+      unified: '1f34d',
+      native: '🍍',
+    }];
+    expect(search('pineapple').map(trimEmojis)).to.deep.equal(expected);
+    expect(emojiIndex.search('pineapple').map(trimEmojis)).to.deep.equal(expected);
+  });
+
+  it('orders search results correctly', () => {
+    let expected = [{
+      id: 'apple',
+      unified: '1f34e',
+      native: '🍎',
+    }, {
+      id: 'pineapple',
+      unified: '1f34d',
+      native: '🍍',
+    }, {
+      id: 'green_apple',
+      unified: '1f34f',
+      native: '🍏',
+    }, {
+      id: 'iphone',
+      unified: '1f4f1',
+      native: '📱',
+    }];
+    expect(search('apple').map(trimEmojis)).to.deep.equal(expected);
+    expect(emojiIndex.search('apple').map(trimEmojis)).to.deep.equal(expected);
+  });
+
+  it('handles custom emoji', () => {
+    let custom = [{
+      id: 'mastodon',
+      name: 'mastodon',
+      short_names: ['mastodon'],
+      text: '',
+      emoticons: [],
+      keywords: ['mastodon'],
+      imageUrl: 'http://example.com',
+      custom: true,
+    }];
+    search('', { custom });
+    emojiIndex.search('', { custom });
+    let expected = [ { id: 'mastodon', custom: true } ];
+    expect(search('masto').map(trimEmojis)).to.deep.equal(expected);
+    expect(emojiIndex.search('masto').map(trimEmojis)).to.deep.equal(expected);
+  });
+
+  it('should filter only emojis we care about, exclude pineapple', () => {
+    let emojisToShowFilter = (unified) => unified !== '1F34D';
+    expect(search('apple', { emojisToShowFilter }).map((obj) => obj.id))
+      .not.to.contain('pineapple');
+    expect(emojiIndex.search('apple', { emojisToShowFilter }).map((obj) => obj.id))
+      .not.to.contain('pineapple');
+  });
+
+  it('can include/exclude categories', () => {
+    expect(search('flag', { include: ['people'] }))
+      .to.deep.equal([]);
+    expect(emojiIndex.search('flag', { include: ['people'] }))
+      .to.deep.equal([]);
+  });
+});