add paramHelper tests

spec/javascripts/vue_pagination/pagination_spec.js.es6

@@ -142,3 +142,25 @@ describe('Pagination component', () => {
     expect(changeChanges.two).toEqual('all');
   });
 });
+
+describe('paramHelper', () => {
+  it('can parse url parameters correctly', () => {
+    window.history.pushState({}, null, '?scope=all&p=2');
+
+    const scope = gl.getParameterByName('scope');
+    const p = gl.getParameterByName('p');
+
+    expect(scope).toEqual('all');
+    expect(p).toEqual('2');
+  });
+
+  it('returns null if param not in url', () => {
+    window.history.pushState({}, null, '?p=2');
+
+    const scope = gl.getParameterByName('scope');
+    const p = gl.getParameterByName('p');
+
+    expect(scope).toEqual(null);
+    expect(p).toEqual('2');
+  });
+});