Updated the test system

test/indexOfAll.test.js

@@ -0,0 +1,12 @@
+const expect = require('expect');
+const {indexOfAll} = require('./_30s.js');
+
+test('indexOfAll is a Function', () => {
+  expect(indexOfAll).toBeInstanceOf(Function);
+});
+test('Returns all indices of val in an array', () => {
+  expect(indexOfAll([1, 2, 3, 1, 2, 3], 1)).toEqual([0, 3]);
+});
+test('When val is not found, return an empty array', () => {
+  expect(indexOfAll([1, 2, 3], 4)).toEqual([]);
+});