Expect assertions

In addition to the assert namespace, the Nightwatch API supports out of the box a BDD-style expect assertion library which greatly improves the flexibility as well as readability of the assertions.

The expect assertions use a subset of the Expect api from the Chai framework and at this point are available for elements, cookies, page title, and url.

Element expect example

Here a basic example that uses various expect.element([...]) assertions: 

module.exports = {
  'Demo test Ecosia.org': function (browser) {
    browser.url('https://www.ecosia.org/');
    

    // expect element header to be present in 1000ms
    browser.expect.element('header').to.be.present.before(1000);
    

    // expect element header to have css property 'display'
    browser.expect.element('header').to.have.css('display');
    

    // expect element header to have attribute 'class' which contains text 'index-header'
    browser.expect.element('header').to.have.attribute('class').which.contains('index-header');
    

    // expect element .search-form to be an input tag
    browser.expect.element('.search-form').to.be.a('form');
    

    // expect element header to be visible
    browser.expect.element('header').to.be.visible;
    

    browser.end();
  }
};

Expecting a specific elements count

In this example, the test is expecting that a specified number of elements exist on the page, using the expect.elements([...]).count assertion: 

module.exports = {
  'demo test ecosia.org'(browser) {
    browser
      .url('https://www.ecosia.org/')
      .expect.elements('section').count.to.equal(5);
  },
  

  after(browser) {
    browser.end();
  }
};

The expect interface provides a much more flexible and fluid language for defining assertions, significantly improved over the existing assert interface. The only downside is that it's not possible to chain assertions anymore.


For a complete list of available expect assertions, refer to the API docs.