Updated the test system

test/hammingDistance.test.js

@@ -0,0 +1,9 @@
+const expect = require('expect');
+const {hammingDistance} = require('./_30s.js');
+
+test('hammingDistance is a Function', () => {
+  expect(hammingDistance).toBeInstanceOf(Function);
+});
+test('retuns hamming disance between 2 values', () => {
+  expect(hammingDistance(2, 3)).toBe(1);
+});