Updated the test system

test/functions.test.js

@@ -0,0 +1,17 @@
+const expect = require('expect');
+const {functions} = require('./_30s.js');
+
+test('functions is a Function', () => {
+  expect(functions).toBeInstanceOf(Function);
+});
+function Foo() {
+  this.a = () => 1;
+  this.b = () => 2;
+}
+Foo.prototype.c = () => 3;
+test('Returns own methods', () => {
+  expect(functions(new Foo())).toEqual(['a', 'b']);
+});
+test('Returns own and inherited methods', () => {
+  expect(functions(new Foo(), true)).toEqual(['a', 'b', 'c']);
+});