Updated the test system

test/pad.test.js

@@ -0,0 +1,18 @@
+const expect = require('expect');
+const {pad} = require('./_30s.js');
+
+test('pad is a Function', () => {
+  expect(pad).toBeInstanceOf(Function);
+});
+test('cat is padded on both sides', () => {
+  expect(pad('cat', 8)).toBe('  cat   ');
+});
+test('length of string is 8', () => {
+  expect(pad('cat', 8).length).toBe(8);
+});
+test('pads 42 with "0"', () => {
+  expect(pad(String(42), 6, '0')).toBe('004200');
+});
+test('does not truncates if string exceeds length', () => {
+  expect(pad('foobar', 3)).toBe('foobar');
+});