fix(ssr): add type check for window (#205)

Also add tests to avoid breaking SSR in the future

other/ssr/__tests__/index.js

@@ -0,0 +1,20 @@
+import React from 'react'
+import ReactDOMServer from 'react-dom/server'
+import Downshift from '../../../src'
+
+test('does not throw an error when server rendering', () => {
+  expect(() => {
+    ReactDOMServer.renderToString(
+      <Downshift id="my-autocomplete-component">
+        {({getInputProps, getLabelProps}) => (
+          <div>
+            <label {...getLabelProps({htmlFor: 'my-autocomplete-input'})} />
+            <input {...getInputProps({id: 'my-autocomplete-input'})} />
+          </div>
+        )}
+      </Downshift>
+    )
+  }).not.toThrow()
+})
+
+/* eslint jsx-a11y/label-has-for:0 */

other/ssr/jest.config.js

@@ -0,0 +1,9 @@
+// This is separate because the test environment is set via the config
+// and we want most of our tests to run with jsdom, but we still want
+// to make sure that the server rendering use case continues to work.
+const jestConfig = require('kcd-scripts/config').jest
+
+module.exports = Object.assign(jestConfig, {
+  roots: ['.'],
+  testEnvironment: 'node',
+})

src/downshift.js

@@ -63,7 +63,10 @@ class Downshift extends Component {
     onStateChange: () => {},
     onUserAction: () => {},
     onChange: () => {},
-    environment: window,
+    environment:
+      typeof window === 'undefined' /* istanbul ignore next (ssr) */
+        ? {}
+        : window,
   }
 
   // this is an experimental feature