Updated the test system

test/partial.test.js

@@ -0,0 +1,13 @@
+const expect = require('expect');
+const {partial} = require('./_30s.js');
+
+test('partial is a Function', () => {
+  expect(partial).toBeInstanceOf(Function);
+});
+function greet(greeting, name) {
+  return greeting + ' ' + name + '!';
+}
+const greetHello = partial(greet, 'Hello');
+test('Prepends arguments', () => {
+  expect(greetHello('John')).toBe('Hello John!');
+});