Updated the test system

test/randomIntegerInRange.test.js

@@ -0,0 +1,15 @@
+const expect = require('expect');
+const {randomIntegerInRange} = require('./_30s.js');
+
+test('randomIntegerInRange is a Function', () => {
+  expect(randomIntegerInRange).toBeInstanceOf(Function);
+});
+const lowerLimit = Math.floor(Math.random() * 20);
+const upperLimit = Math.floor(lowerLimit + Math.random() * 10);
+test('The returned value is an integer', () => {
+  expect(Number.isInteger(randomIntegerInRange(lowerLimit, upperLimit))).toBeTruthy();
+});
+const numberForTest = randomIntegerInRange(lowerLimit, upperLimit);
+test('The returned value lies between provided lowerLimit and upperLimit (both inclusive).', () => {
+  expect(numberForTest >= lowerLimit && numberForTest <= upperLimit).toBeTruthy();
+});