Improve tests for JavaScript (#3496)

- Upgrade dependencies
    - chai (3.5.0 -> 4.0.1)
    - chai-enzyme (0.6.1 -> 0.7.1)
    - sinon (2.2.0 -> 2.3.2)
- Change extensions from .jsx to .js
- Don't assign `React` to `global`
- Check code format using ESLint

1 files changed, 1 insertions, 1 deletions

diff --git a/spec/javascript/components/features/ui/components/column.test.jsx b/spec/javascript/components/features/ui/components/column.test.js
index 6359905e6..df0f43e60 100644
--- a/spec/javascript/components/features/ui/components/column.test.jsx
+++ b/spec/javascript/components/features/ui/components/column.test.js
@@ -1,7 +1,7 @@
 import { expect } from 'chai';
 import { mount } from 'enzyme';
 import sinon from 'sinon';
-
+import React from 'react';
 import Column from '../../../../../../app/javascript/mastodon/features/ui/components/column';
 import ColumnHeader from '../../../../../../app/javascript/mastodon/features/ui/components/column_header';