Add broken test and uncovered code

Author: morgan-atproperties

sum.js

@@ -1,4 +1,9 @@
 function sum(a, b) {
   return a + b;
 }
-module.exports = sum;
+
+function multiply(a, b) {
+  return a * b;
+}
+
+module.exports = sum;

sum.test.js

@@ -2,4 +2,8 @@ const sum = require('./sum');
 
 test('adds 1 + 2 to equal 3', () => {
   expect(sum(1, 2)).toBe(3);
-});
+});
+
+test('adds 1 + 2 to equal 4', () => {
+  expect(sum(1, 2)).toBe(4);
+});