Running the same mocha test multiple times with different data

Question

Problem

I have several tests that do the same thing in mocha. This for me, it's duplication, and is the worst thing to do when you want your system to be maintenable.

var exerciseIsPetitionActive = function (expected, dateNow) {     var actual = sut.isPetitionActive(dateNow);     chai.assert.equal(expected, actual); };  test('test_isPetitionActive_calledWithDateUnderNumSeconds_returnTrue', function () {     exerciseIsPetitionActive(true, new Date('2013-05-21 13:11:34')); });  test('test_isPetitionActive_calledWithDateGreaterThanNumSeconds_returnFalse', function () {     exerciseIsPetitionActive(false, new Date('2013-05-21 13:12:35')); }); 

What do I need

I need a way of collapsing my duplicated mocha tests in only one.

For example, in PhpUnit (and other test frameworks) you have dataProviders.
In phpUnit a dataProvider works this way:

<?php class DataTest extends PHPUnit_Framework_TestCase {     /**      * @dataProvider provider      */     public function testAdd($a, $b, $c)     {         $this->assertEquals($c, $a + $b);     }      public function provider()     {         return array(           array(0, 0, 0),           array(0, 1, 1),           array(1, 0, 1),           array(1, 1, 3)         );     } } 

The provider in here injects parameters to the test, and the test executes all the cases. Is perfect for duplicated test.

I want to know if in mocha is there something similar, for example, something like this:

var exerciseIsPetitionActive = function (expected, dateNow) {     var actual = sut.isPetitionActive(dateNow);     chai.assert.equal(expected, actual); };  @usesDataProvider myDataProvider test('test_isPetitionActive_calledWithParams_returnCorrectAnswer', function (expected, date) {     exerciseIsPetitionActive(expected, date); });  var myDataProvider = function() {   return {       {true, new Date(..)},       {false, new Date(...)}   }; }; 

What I have already looked at

There is some tecnique that is called Shared Behaviours . But it does not solve the problem directly with a test suite, it just solve the problem with different components that have duplicated tests.

The Question

Do you know any way to implement dataProviders in mocha?

Answer 1

A basic approach to run the same test with different data is to repeat the test in a loop providing the data:

describe('my tests', function () {   var runs = [     {it: 'options1', options: {...}},     {it: 'options2', options: {...}},   ];    before(function () {     ...   });    runs.forEach(function (run) {     it('does sth with ' + run.it, function () {       ...     });   }); }); 

before runs, well, before all its in a describe. If you need to use some of the options in before, do not include it in the forEach loop because mocha will first run all befores and the all its, which is probably not wanted. You can either put the whole describe in the loop:

var runs = [   {it: 'options1', options: {...}},   {it: 'options2', options: {...}}, ];  runs.forEach(function (run) {   describe('my tests with ' + run.it, function () {     before(function () {       ...     });      it('does sth with ' + run.it, function () {       ...     });   }); }); 

If you do not wish to pollute your tests with multiple describes, you can use the controversial module sinon for this matter:

var sinon = require('sinon');  describe('my tests', function () {   var runs = [     {it: 'options1', options: {...}},     {it: 'options2', options: {...}},   ];    // use a stub to return the proper configuration in `beforeEach`   // otherwise `before` is called all times before all `it` calls   var stub = sinon.stub();   runs.forEach(function (run, idx) {     stub.onCall(idx).returns(run);   });    beforeEach(function () {     var run = stub();     // do something with the particular `run.options`   });    runs.forEach(function (run, idx) {     it('does sth with ' + run.it, function () {       sinon.assert.callCount(stub, idx + 1);       ...     });   }); }); 

Sinon feels dirty but is effective. Several aid modules such as leche are based on sinon, but arguably introducing further complexity is not necessary.

Answer 2

Mocha doesn't provide a tool for that, but it is easy to do it yourself. You only need to run the tests inside a loop and give the data to the test function using a closure:

suite("my test suite", function () {     var data = ["foo", "bar", "buzz"];     var testWithData = function (dataItem) {         return function () {             console.log(dataItem);             //Here do your test.         };     };      data.forEach(function (dataItem) {         test("data_provider test", testWithData(dataItem));     }); });