ran npm run tdd & generated TDD

test/join/join.js

@@ -0,0 +1,8 @@
+module.exports = (arr, separator = ',', end = separator) =>
+arr.reduce(
+(acc, val, i) =>
+i == arr.length - 2
+? acc + val + end
+: i == arr.length - 1 ? acc + val : acc + val + separator,
+''
+);

test/join/join.test.js

@@ -0,0 +1,13 @@
+const test = require('tape');
+const join = require('./join.js');
+
+test('Testing join', (t) => {
+	//For more information on all the methods supported by tape
+	//Please go to https://github.com/substack/tape
+	t.true(typeof join === 'function', 'join is a Function');
+	//t.deepEqual(join(args..), 'Expected');
+	//t.equal(join(args..), 'Expected');
+	//t.false(join(args..), 'Expected');
+	//t.throws(join(args..), 'Expected');
+	t.end();
+});