Updated the test system

test/isUpperCase.test.js

@@ -0,0 +1,15 @@
+const expect = require('expect');
+const {isUpperCase} = require('./_30s.js');
+
+test('isUpperCase is a Function', () => {
+  expect(isUpperCase).toBeInstanceOf(Function);
+});
+test('ABC is all upper case', () => {
+  expect(isUpperCase('ABC')).toBeTruthy();
+});
+test('abc is not all upper case', () => {
+  expect(isUpperCase('abc')).toBeFalsy();
+});
+test('A3@$ is all uppercase', () => {
+  expect(isUpperCase('A3@$')).toBeTruthy();
+});