Test migration to jest by hand

Apparently using regular expressions is way easier.

test/flatten/flatten.test.js

@@ -0,0 +1,10 @@
+const expect = require('expect');
+const flatten = require('./flatten.js');
+
+
+  test('flatten is a Function', () => {
+  expect(flatten).toBeInstanceOf(Function);
+});
+  t.deepEqual(flatten([1, [2], 3, 4]), [1, 2, 3, 4], "Flattens an array");
+  t.deepEqual(flatten([1, [2, [3, [4, 5], 6], 7], 8], 2), [1, 2, 3, [4, 5], 6, 7, 8], "Flattens an array");
+