Add tests for undefined query params

Fixes #169

modules/utils/__tests__/createSearch-test.js

@@ -5,6 +5,11 @@ describe('createSearch', () => {
     expect(createSearch({ a: 'a', b: '' })).toEqual('?a=a&b');
   });
 
+  it('omits the trailing = for null/undefined values', () => {
+    expect(createSearch({ a: 'a', b: null })).toEqual('?a=a&b');
+    expect(createSearch({ a: 'a', b: undefined })).toEqual('?a=a&b');
+  });
+
   it('sorts keys', () => {
     expect(createSearch({ b: 'b', a: 'a', c: 'c' })).toEqual('?a=a&b=b&c=c');
   });

modules/utils/createSearch.js

@@ -1,12 +1,14 @@
 export default function createSearch(query) {
   const keys = Object.keys(query).sort();
-  const params = keys.reduce(
+  const pairs = keys.reduce(
     (memo, key) =>
       memo.concat(
-        query[key] ? `${key}=${encodeURIComponent(query[key])}` : key
+        query[key] == null || query[key] === ''
+          ? key
+          : `${key}=${encodeURIComponent(query[key])}`
       ),
     []
   );
 
-  return params.length ? `?${params.join('&')}` : '';
+  return pairs.length ? `?${pairs.join('&')}` : '';
 }