Updated the test system

test/bind.test.js

@@ -0,0 +1,14 @@
+const expect = require('expect');
+const {bind} = require('./_30s.js');
+
+test('bind is a Function', () => {
+  expect(bind).toBeInstanceOf(Function);
+});
+function greet(greeting, punctuation) {
+  return greeting + ' ' + this.user + punctuation;
+}
+const freddy = { user: 'fred' };
+const freddyBound = bind(greet, freddy);
+test('Binds to an object context', () => {
+  expect(freddyBound('hi', '!')).toBe('hi fred!');
+});