Updated the test system

test/capitalize.test.js

@@ -0,0 +1,18 @@
+const expect = require('expect');
+const {capitalize} = require('./_30s.js');
+
+test('capitalize is a Function', () => {
+  expect(capitalize).toBeInstanceOf(Function);
+});
+test('Capitalizes the first letter of a string', () => {
+  expect(capitalize('fooBar')).toBe('FooBar');
+});
+test('Capitalizes the first letter of a string', () => {
+  expect(capitalize('fooBar', true)).toBe('Foobar');
+});
+test('Works with characters', () => {
+  expect(capitalize('#!#', true)).toBe('#!#');
+});
+test('"Works with single character words', () => {
+  expect(capitalize('a', true)).toBe('A');
+});