UI2API

As more web applications make use of an interface to interact with their service layer, people now have more flexibility to set up and verify parts of their UI tests without needing to use a browser.

This simple gem makes it easy to subclass UI2API::Base and provide all of the information necessary to interact with the different REST endpoints available in your application.

This code is designed to be used with the watir_model gem. The Model stores data in a way that makes it easy to compare the input and output from both the API and the UI.

Note that while this gem can be used as the basis of an API Testing suite, its primary focus is on comparing input and output from UI to API and back.

Installation

Add this line to your application's Gemfile:

gem 'ui2api'

And then execute:

$ bundle

Or install it yourself as:

$ gem install ui2api

Usage

Set the base url ruby UI2API::Base.base_url = 'https://restful-booker.herokuapp.com'

Create a subclass with an endpoint:

module API
  class Booking < UI2API::Base
    def self.endpoint
      'booking'
    end
  end
end

Make API calls

booking = {firstname: 'Trey',
           lastname: 'Ruecker',
           totalprice: 83,
           depositpaid: true,
           bookingdates: {checkin: '3/23/2019',
                          checkout: '3/27/2019'}}

API::Booking.create(booking)

The Array or Hash of results is accessed with #data

booking = {firstname: 'David',
           lastname: 'Jones',
           totalprice: 183,
           depositpaid: true,
           bookingdates: {checkin: '3/23/2019',
                          checkout: '3/27/2019'}}

created_booking = API::Booking.create(booking)
booking_id = created_booking.data[:bookingid]

stored_booking = API::Booking.show(id: booking_id).data

expect(stored_booking).to eq booking

Use Watir Model

Note that the code in the previous example will actually fail. This is because we are storing dates as String values and the input String does not match the output String

Hashes are hard to compare, which is why we have WatirModel. WatirModel is designed to store the canonical representation of related data in the appropriate data type, specifically so that data can be correctly compared.

module Model
  class BookingDates < WatirModel
    key(:checkin, data_type: Date) { Faker::Date.forward }
    key(:checkout, data_type: Date) { checkin + 4 }
  end

  class Booking < WatirModel
    key(:firstname) { Faker::Name.first_name }
    key(:lastname) { Faker::Name.last_name }
    key(:totalprice, data_type: Integer) { Faker::Commerce.price.round }
    key(:depositpaid) { true }
    key(:bookingdates, data_type: BookingDates) { BookingDates.new }
    key(:additionalneeds)
  end
end

Because we have a model class defined that is named the same as the API class, UI2API will automatically attempt to create an instance of the model from the return value of the API call. It is accessible from a method based on the name of the API/Model classes, so in this case #booking:

booking = Model::Booking.new

created_booking = API::Booking.create(booking)
booking_id = created_booking.data[:bookingid]

stored_booking = API::Booking.show(id: booking_id).booking

expect(stored_booking).to eq booking

Customize

You have a subclass, so if you need to add or change things before or after a call, just override the UI2API method in your subclass:

module API
  class Booking < UI2API::Base

    attr_reader :id

    def initialize(*)
      super
      return if @data.is_a?(Array)
      @id = @data[:bookingid]
    end
  end
end

Now we can use this like so:

booking = Model::Booking.new

created_booking = API::Booking.create(booking)

expect(created_booking.id).to eq created_booking.data[:bookingid]

Because this pattern comes in very handy, you can use #define_attribute to do the same thing:

module API
  class Booking < UI2API::Base
    def initialize(*)
      super
      return if @data.is_a?(Array)
      define_attribute(:id, @data[:bookingid])
    end
  end
end

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/titusfortner/ui2api.

History

While I've been leveraging this approach at my past few jobs, my solutions were application specific and <cough> not satisfyingly elegant. My initial attempts at implementing this gem were much too over-engineered and weren't solving the actual general use case, so this project has stayed on the shelf in spite of the industry need for it. Then at the 2017 Selenium Conference in Berlin, Mark Winteringham gave a talk titled REST APIs and WebDriver: In Perfect Harmony. This gave me the outside vantage point I needed to see how to focus the project. I started by copying the functionality of the code in Mark's repo, and then added in some extra goodness that leveraging WatirModel provides.

License

The gem is available as open source under the terms of the MIT License.