Test migration to jest by hand

Apparently using regular expressions is way easier.

test/once/once.js

@@ -0,0 +1,9 @@
+const once = fn => {
+let called = false;
+return function(...args) {
+if (called) return;
+called = true;
+return fn.apply(this, args);
+};
+};
+module.exports = once;

test/once/once.test.js

@@ -0,0 +1,10 @@
+const expect = require('expect');
+const once = require('./once.js');
+
+
+  test('once is a Function', () => {
+  expect(once).toBeInstanceOf(Function);
+});
+  t.pass('Tested by @chalarangelo on 16/02/2018');
+  
+