README.md

Sinon sample code from Best Practices for Spies, Stubs and Mocks in Sinon.js

sinon.js

/* global describe, before, it */

'use strict';

var sinon = require('sinon');

describe('sinon best practices', function() { 

    var Database = {
        save: function() {}
    };

    function setupNewUser(info, callback) {
        var user = {
            name: info.name,
            nameLowercase: info.name.toLowerCase()
        };

        try {
            Database.save(user, callback);
        }
        catch(err) {
            callback(err);
        }
    }

    it('should call save once', function() {
        var save = sinon.spy(Database, 'save');

        setupNewUser({ name: 'test' }, function() { });

        save.restore();
        sinon.assert.calledOnce(save);
    });

    it('should pass object with correct values to save (using spy)', function() {
        var save = sinon.spy(Database, 'save');
        var info = { name: 'test' };
        var expectedUser = {
            name: info.name,
            nameLowercase: info.name.toLowerCase()
        };

        setupNewUser(info, function() { });

        save.restore();
        sinon.assert.calledWith(save, expectedUser);
    });

    it('should pass object with correct values to save (using stub)', function() {
        var save = sinon.stub(Database, 'save');
        var info = { name: 'test' };
        var expectedUser = {
            name: info.name,
            nameLowercase: info.name.toLowerCase()
        };

        setupNewUser(info, function() { });

        save.restore();
        sinon.assert.calledWith(save, expectedUser);
    });

    it('should pass the error into the callback if save fails', function() {
        var expectedError = new Error('oops');
        var save = sinon.stub(Database, 'save');
        save.throws(expectedError);
        var callback = sinon.spy();

        setupNewUser({ name: 'foo' }, callback);

        save.restore();
        sinon.assert.calledWith(callback, expectedError);
    });

    it('should pass the database result into the callback', function() {
        var expectedResult = { success: true };
        var save = sinon.stub(Database, 'save');
        save.yields(null, expectedResult);
        var callback = sinon.spy();

        setupNewUser({ name: 'foo' }, callback);

        save.restore();
        sinon.assert.calledWith(callback, null, expectedResult);
    });

    it('should pass object with correct values to save only once', function() {
        var info = { name: 'test' };
        var expectedUser = {
            name: info.name,
            nameLowercase: info.name.toLowerCase()
        };
        var database = sinon.mock(Database);
        database.expects('save').once().withArgs(expectedUser);

        setupNewUser(info, function() { });

        database.verify();
        database.restore();
    });
});