Configure frontend tests (#1293)

While working on #1288 I configured frontend tests. I'm going in a different direction with that, though it seems worth keeping the test configuration. I added tests for one of the helper methods.

frontend/lib/static-badge-uri.spec.js

@@ -0,0 +1,17 @@
+import { test, given } from 'sazerac';
+import { encodeField, default as staticBadgeUri } from './static-badge-uri';
+
+describe('Static badge URI generator', function() {
+  test(encodeField, () => {
+    given('foo').expect('foo');
+    given('').expect('');
+    given('happy go lucky').expect('happy%20go%20lucky');
+    given('do-right').expect('do--right');
+    given('it_is_a_snake').expect('it__is__a__snake');
+  });
+
+  test(staticBadgeUri, () => {
+    given('http://img.example.com', 'foo', 'bar', 'blue', { style: 'plastic'})
+      .expect('http://img.example.com/badge/foo-bar-blue.svg?style=plastic');
+  });
+});