Add isPowerOfTwo snippet

test/isPowerOfTwo.test.js

@@ -0,0 +1,29 @@
+const {isPowerOfTwo} = require('./_30s.js');
+
+test('isPowerOfTwo is a Function', () => {
+  expect(isPowerOfTwo).toBeInstanceOf(Function);
+});
+test('0 is not a power of 2', () => {
+  expect(isPowerOfTwo(0)).toBeFalsy();
+});
+test('1 is a power of 2', () => {
+  expect(isPowerOfTwo(1)).toBeTruthy();
+});
+test('2 is a power of 2', () => {
+  expect(isPowerOfTwo(2)).toBeTruthy();
+});
+test('3 is not a power of 2', () => {
+  expect(isPowerOfTwo(3)).toBeFalsy();
+});
+test('4 is a power of 2', () => {
+  expect(isPowerOfTwo(4)).toBeTruthy();
+});
+test('5 is not a power of 2', () => {
+  expect(isPowerOfTwo(5)).toBeFalsy();
+});
+test('6 is not a power of 2', () => {
+  expect(isPowerOfTwo(6)).toBeFalsy();
+});
+test('undefined is not a power of 2', () => {
+  expect(isPowerOfTwo()).toBeFalsy();
+});