Test migration to jest by hand

Apparently using regular expressions is way easier.

test/symmetricDifferenceWith/symmetricDifferenceWith.test.js

@@ -0,0 +1,14 @@
+const expect = require('expect');
+const symmetricDifferenceWith = require('./symmetricDifferenceWith.js');
+
+
+  test('symmetricDifferenceWith is a Function', () => {
+  expect(symmetricDifferenceWith).toBeInstanceOf(Function);
+});
+  t.deepEqual(symmetricDifferenceWith(
+  [1, 1.2, 1.5, 3, 0],
+  [1.9, 3, 0, 3.9],
+  (a, b) => Math.round(a) === Math.round(b)
+), [1, 1.2, 3.9], 'Returns the symmetric difference between two arrays, using a provided function as a comparator');
+  
+