Migrated tests to jest

Used jest-codemods to migrate, will have to pass everything by hand before we can merge.

test2/differenceWith/differenceWith.test.js

@@ -0,0 +1,11 @@
+const expect = require('expect');
+const differenceWith = require('./differenceWith.js');
+
+test('Testing differenceWith', () => {
+  //For more information on all the methods supported by tape
+  //Please go to https://github.com/substack/tape
+  expect(typeof differenceWith === 'function').toBeTruthy();
+  expect(
+    differenceWith([1, 1.2, 1.5, 3, 0], [1.9, 3, 0], (a, b) => Math.round(a) === Math.round(b))
+  ).toEqual([1, 1.2]);
+});