Updated the test system

test/isSorted.test.js

@@ -0,0 +1,39 @@
+const expect = require('expect');
+const {isSorted} = require('./_30s.js');
+
+test('isSorted is a Function', () => {
+  expect(isSorted).toBeInstanceOf(Function);
+});
+test('Array is sorted in ascending order', () => {
+  expect(isSorted([0, 1, 2])).toBe(1);
+});
+test('Array is sorted in ascending order', () => {
+  expect(isSorted([0, 1, 2, 2])).toBe(1);
+});
+test('Array is sorted in ascending order', () => {
+  expect(isSorted([-4, -3, -2])).toBe(1);
+});
+test('Array is sorted in ascending order', () => {
+  expect(isSorted([0, 0, 1, 2])).toBe(1);
+});
+test('Array is sorted in descending order', () => {
+  expect(isSorted([2, 1, 0])).toBe(-1);
+});
+test('Array is sorted in descending order', () => {
+  expect(isSorted([2, 2, 1, 0])).toBe(-1);
+});
+test('Array is sorted in descending order', () => {
+  expect(isSorted([-2, -3, -4])).toBe(-1);
+});
+test('Array is sorted in descending order', () => {
+  expect(isSorted([2, 1, 0, 0])).toBe(-1);
+});
+test('Array is empty', () => {
+  expect(isSorted([])).toBe(undefined);
+});
+test('Array is not sorted, direction changed in array', () => {
+  expect(isSorted([1])).toBe(0);
+});
+test('Array is not sorted, direction changed in array', () => {
+  expect(isSorted([1, 2, 1])).toBe(0);
+});