Updated the test system

test/pipeFunctions.test.js

@@ -0,0 +1,12 @@
+const expect = require('expect');
+const {pipeFunctions} = require('./_30s.js');
+
+test('pipeFunctions is a Function', () => {
+  expect(pipeFunctions).toBeInstanceOf(Function);
+});
+const add5 = x => x + 5;
+const multiply = (x, y) => x * y;
+const multiplyAndAdd5 = pipeFunctions(multiply, add5);
+test('Performs left-to-right function composition', () => {
+  expect(multiplyAndAdd5(5, 2)).toBe(15);
+});