Updated the test system

test/filterNonUnique.test.js

@@ -0,0 +1,9 @@
+const expect = require('expect');
+const {filterNonUnique} = require('./_30s.js');
+
+test('filterNonUnique is a Function', () => {
+  expect(filterNonUnique).toBeInstanceOf(Function);
+});
+test('Filters out the non-unique values in an array', () => {
+  expect(filterNonUnique([1, 2, 2, 3, 4, 4, 5])).toEqual([1, 3, 5]);
+});