Updated the test system

test/pullBy.test.js

@@ -0,0 +1,11 @@
+const expect = require('expect');
+const {pullBy} = require('./_30s.js');
+
+test('pullBy is a Function', () => {
+  expect(pullBy).toBeInstanceOf(Function);
+});
+var myArray = [{ x: 1 }, { x: 2 }, { x: 3 }, { x: 1 }];
+pullBy(myArray, [{ x: 1 }, { x: 3 }], o => o.x);
+test('Pulls the specified values', () => {
+  expect(myArray).toEqual([{ x: 2 }]);
+});