Tutorial

This tutorial demonstrates Yadda with Node.js and Mocha. If you prefer another test runner, see the examples.

Start a new node project

mkdir yadda-tutorial
cd yadda-tutorial
npm init
npm i --save-dev yadda mocha

Create a test directory structure

mkdir -p test/features test/steps

Write a feature specification

Feature: 100 Green Bottles

Scenario: Should fall from the wall

   Given 100 green bottles are standing on the wall
   When 1 green bottle accidentally falls
   Then there are 99 green bottles standing on the wall

Save it in test/features/bottles.feature

Implement the steps library

var assert = require('assert');
var English = require('yadda').localisation.English;
var Wall = require('../..'); // The library that you wish to test

module.exports = English.library()
    .given("$NUM green bottles are standing on the wall", function(number, next) {
        wall = new Wall(number);
        next();
    })
    .when("$NUM green bottle accidentally falls", function(number, next) {
        wall.fall(number);
        next();
    })
    .then("there are $NUM green bottles standing on the wall", function(number, next) {
        assert.equal(number, wall.bottles);
        next();
    });

Save it in test/steps/bottles-library.js. If your test runner & code are synchronous you can omit calls to 'next'.

Integrate Yadda with Mocha

var Yadda = require('yadda');
Yadda.plugins.mocha.StepLevelPlugin.init();

new Yadda.FeatureFileSearch('./test/features').each(function(file) {

    featureFile(file, function(feature) {

        var library = require('./test/steps/bottles-library');
        var yadda = Yadda.createInstance(library);

        scenarios(feature.scenarios, function(scenario) {
            steps(scenario.steps, function(step, done) {
                yadda.run(step, done);
            });
        });
    });
});

Save it in ./test.js.

Write the code under test

module.exports = function(bottles) {
    this.bottles = bottles;
        this.fall = function(n) {
        this.bottles -= n;
    }
};

Save it in ./index.js. By now your project should have the following layout.

.
├── index.js
├── package.json
├── test.js
└── test
    ├── features
    │   └── bottles.feature
    └── steps
        └── bottles-library.js

Run your tests

mocha --reporter spec test.js

100 Green Bottles
Should fall from the wall
  ✓ Given 100 green bottles are standing on the wall
  ✓ When 1 green bottle accidentally falls
  ✓ Then there are 99 green bottles standing on the wall