Transfer Promises

Since v3 of WebdriverIO every command represents a promise. This allows us to introduce some neat testing features when adding promised based assertion libraries like chai-as-promised.

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it('should contain a certain text after clicking', function() {
    return client
        .click('button=Send')
        .isVisible('#status_message').then(function(isVisible) {
            assert.ok(isVisible, 'status message is not visible');
        })
        .getText('#status_message').then(function(message) {
            assert.ok(message === 'Message sent!', 'wrong status message');
        });
});

The example above shows a simple integration test where a user clicks on a “Send” button and a message gets send. The test checks if a status message gets displayed with a certain text. This already looks pretty straightforward but by adding an assertion library like chai-as-promised we can shorten everything even more.

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before(function() {
    var chai = require('chai');
    var chaiAsPromised = require('chai-as-promised');
 
    chai.Should();
    chai.use(chaiAsPromised);
    chaiAsPromised.transferPromiseness = client.transferPromiseness;
});

Put this somewhere in your test setup (e.g. the before or onPrepare hook). It initialises Chai as assertion library and hooks up WebdriverIO with chai-as-promised by setting the transferPromiseness function to the internal one of WebdriverIO. This allows us to write super simple assertions like:

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it('should contain a certain text after clicking', function() {
    return client
        .click('button=Send')
        .isVisible('#status_message').should.eventually.be.true
        .getText('#status_message').should.eventually.be.equal('Message sent!');
});