Add gist test

cypress/integration/gist.js

@@ -0,0 +1,13 @@
+/* eslint-env mocha */
+/* global cy */
+import { editorVisible } from '../support'
+describe('Gist', () => {
+  const themeDropdown = () => cy.get('#toolbar .dropdown-container').first()
+
+  it('Should pull text from the first Gist file', () => {
+    cy.visit('/3208813b324d82a9ebd197e4b1c3bae8')
+    editorVisible()
+
+    cy.contains('Y-Combinator implemented in JavaScript')
+  })
+})