Add deprecated index tests

Author: Thomas

package.json

@@ -1,6 +1,6 @@
 {
   "name": "nhsuk-react-components",
-  "version": "1.2.8-dev1",
+  "version": "1.2.8",
   "author": {
     "email": "[email protected]",
     "name": "Thomas Judd-Cooper",

src/deprecated/__tests__/index.test.ts

@@ -0,0 +1,7 @@
+import * as deprecatedIndex from '../index';
+
+describe('DeprecatedIndex', () => {
+  it('contains all expected elements', () => {
+    expect(Object.keys(deprecatedIndex)).toEqual(['Panel', 'Promo']);
+  });
+});