Enable some eslint-plugin-jsx-a11y rules

- `jsx-a11y/click-events-have-key-events` as a warning
- `jsx-a11y/mouse-events-have-key-events` as a warning
- `jsx-a11y/no-onchange` as an error
- `jsx-a11y/onclick-has-focus` as an error
- `jsx-a11y/onclick-has-role` as an error

rules/__tests__/react-a11y.test.js

@@ -0,0 +1,12 @@
+import { rules } from '../react-a11y'
+
+describe('react-a11y rules', () => {
+  it('contains only react-a11y rules', () => {
+    const keys = Object.keys(rules)
+    const expected = Array.from(
+      keys, () => expect.stringMatching(/^jsx-a11y\/.+$/),
+    )
+
+    expect(keys).toEqual(expected)
+  })
+})

rules/react-a11y.js

@@ -0,0 +1,19 @@
+module.exports = {
+  rules: {
+    // require onClick be accompanied by onKeyUp/onKeyDown/onKeyPress
+    // https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/click-events-have-key-events.md
+    'jsx-a11y/click-events-have-key-events': 'warn',
+    // require that mouseover/out come with focus/blur, for keyboard-only users
+    // https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/mouse-events-have-key-events.md
+    'jsx-a11y/mouse-events-have-key-events': 'warn',
+    // require onBlur instead of onChange
+    // https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-onchange.md
+    'jsx-a11y/no-onchange': 'error',
+    // Enforce that elements with onClick handlers must be focusable.
+    // https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/onclick-has-focus.md
+    'jsx-a11y/onclick-has-focus': 'error',
+    // require things with onClick to have an aria role
+    // https://github.com/evcohen/eslint-plugin-jsx-a11y/blob/master/docs/rules/onclick-has-role.md
+    'jsx-a11y/onclick-has-role': 'error',
+  },
+}