Updated the test system

test/median.test.js

@@ -0,0 +1,12 @@
+const expect = require('expect');
+const {median} = require('./_30s.js');
+
+test('median is a Function', () => {
+  expect(median).toBeInstanceOf(Function);
+});
+test('Returns the median of an array of numbers', () => {
+  expect(median([5, 6, 50, 1, -5])).toBe(5);
+});
+test('Returns the median of an array of numbers', () => {
+  expect(median([1, 2, 3])).toBe(2);
+});