Types of tests

1. unit test
2. integrated test
3. functional test

Mock objects are used to define expectations i.e: In this scenario I expect method A() to be called with such and such parameters. Mocks record and verify such expectations.

Title Text

it('calls the original function', function () {
    var callback = sinon.spy();
    var proxy = once(callback);

    proxy();

    assert(callback.called);
});

Stubs, on the other hand have a different purpose: they do not record or verify expectations, but rather allow us to “replace” the behavior, state of the “fake”object in order to utilize a test scenario

var handler = function(callback){
    //stupid handler that makes every file urgent
    fs.readFile("/this/path/does/not/exist/", function(err, data) {
        if (err) {
            console.log(err)
        }

        callback(data+"!!!!");

    })
}

module.exports = handler

var fs = require('fs');
var sinon = require('sinon');

sinon.stub(fs, 'readFile').yields(null, "LOLYESITDOES")

var test = require('tape');
var handler = require('./script.js')
test ('test the urgent handler', function(t){
     handler(function(data){
        t.equal(data, "LOLYESITDOES!!!!")
        t.end()
     })
});

When to write a test

1. Classic
2. TDD / BDD