Add aria-describedby attribute

src/Select.js

@@ -77,6 +77,8 @@ type FormatOptionLabelMeta = {
 };
 
 export type Props = {
+  /* HTML ID of an element that should be used to describe this input (for assistive tech) */
+  'aria-describedby'?: string,
   /* Aria label (for assistive tech) */
   'aria-label'?: string,
   /* HTML ID of an element that should be used as the label (for assistive tech) */
@@ -1399,6 +1401,7 @@ export default class Select extends Component<Props, State> {
     // aria attributes makes the JSX "noisy", separated for clarity
     const ariaAttributes = {
       'aria-autocomplete': 'list',
+      'aria-describedby': this.props['aria-describedby'],
       'aria-label': this.props['aria-label'],
       'aria-labelledby': this.props['aria-labelledby'],
     };

src/__tests__/Select.test.js

@@ -1507,6 +1507,26 @@ cases(
   }
 );
 
+cases(
+  'accessibility > passes through aria-describedby prop',
+  ({ props = { ...BASIC_PROPS, 'aria-describedby': 'testing' } }) => {
+    let selectWrapper = mount(<Select {...props} />);
+    expect(selectWrapper.find('Control input').props()['aria-describedby']).toBe(
+      'testing'
+    );
+  },
+  {
+    'single select > should pass aria-describedby prop down to input': {},
+    'multi select > should pass aria-describedby prop down to input': {
+      props: {
+        ...BASIC_PROPS,
+        'aria-describedby': 'testing',
+        isMulti: true,
+      },
+    },
+  }
+);
+
 cases(
   'accessibility > passes through aria-labelledby prop',
   ({ props = { ...BASIC_PROPS, 'aria-labelledby': 'testing' } }) => {