Resource class in GitLab QA

Resources are primarily created using Browser UI steps, but can also be created via the API or the CLI.

How to properly implement a resource class?

All resource classes should inherit from Resource::Base.

There is only one mandatory method to implement to define a resource class. This is the #fabricate! method, which is used to build the resource via the browser UI. Note that you should only use Page objects to interact with a Web page in this method.

Here is an imaginary example:

module QA
  module Resource
    class Shirt < Base
      attr_accessor :name

      def fabricate!
        Page::Dashboard::Index.perform do |dashboard_index|
          dashboard_index.go_to_new_shirt
        end

        Page::Shirt::New.perform do |shirt_new|
          shirt_new.set_name(name)
          shirt_new.create_shirt!
        end
      end
    end
  end
end

Define API implementation

A resource class may also implement the three following methods to be able to create the resource via the public GitLab API:

  • #api_get_path: The GET path to fetch an existing resource.
  • #api_post_path: The POST path to create a new resource.
  • #api_post_body: The POST body (as a Ruby hash) to create a new resource.

Let’s take the Shirt resource class, and add these three API methods:

module QA
  module Resource
    class Shirt < Base
      attr_accessor :name

      def fabricate!
        # ... same as before
      end

      def api_get_path
        "/shirt/#{name}"
      end

      def api_post_path
        "/shirts"
      end

      def api_post_body
        {
          name: name
        }
      end
    end
  end
end

The Project resource is a good real example of Browser UI and API implementations.

Resource attributes

A resource may need another resource to exist first. For instance, a project needs a group to be created in.

To define a resource attribute, you can use the attribute method with a block using the other resource class to fabricate the resource.

That will allow access to the other resource from your resource object’s methods. You would usually use it in #fabricate!, #api_get_path, #api_post_path, #api_post_body.

Let’s take the Shirt resource class, and add a project attribute to it:

module QA
  module Resource
    class Shirt < Base
      attr_accessor :name

      attribute :project do
        Project.fabricate! do |resource|
          resource.name = 'project-to-create-a-shirt'
        end
      end

      def fabricate!
        project.visit!

        Page::Project::Show.perform do |project_show|
          project_show.go_to_new_shirt
        end

        Page::Shirt::New.perform do |shirt_new|
          shirt_new.set_name(name)
          shirt_new.create_shirt!
        end
      end

      def api_get_path
        "/project/#{project.path}/shirt/#{name}"
      end

      def api_post_path
        "/project/#{project.path}/shirts"
      end

      def api_post_body
        {
          name: name
        }
      end
    end
  end
end

Note that all the attributes are lazily constructed. This means if you want a specific attribute to be fabricated first, you’ll need to call the attribute method first even if you’re not using it.

Product data attributes

Once created, you may want to populate a resource with attributes that can be found in the Web page, or in the API response. For instance, once you create a project, you may want to store its repository SSH URL as an attribute.

Again we could use the attribute method with a block, using a page object to retrieve the data on the page.

Let’s take the Shirt resource class, and define a :brand attribute:

module QA
  module Resource
    class Shirt < Base
      attr_accessor :name

      attribute :project do
        Project.fabricate! do |resource|
          resource.name = 'project-to-create-a-shirt'
        end
      end

      # Attribute populated from the Browser UI (using the block)
      attribute :brand do
        Page::Shirt::Show.perform do |shirt_show|
          shirt_show.fetch_brand_from_page
        end
      end

      # ... same as before
    end
  end
end

Note again that all the attributes are lazily constructed. This means if you call shirt.brand after moving to the other page, it’ll not properly retrieve the data because we’re no longer on the expected page.

Consider this:

shirt =
  QA::Resource::Shirt.fabricate! do |resource|
    resource.name = "GitLab QA"
  end

shirt.project.visit!

shirt.brand # => FAIL!

The above example will fail because now we’re on the project page, trying to construct the brand data from the shirt page, however we moved to the project page already. There are two ways to solve this, one is that we could try to retrieve the brand before visiting the project again:

shirt =
  QA::Resource::Shirt.fabricate! do |resource|
    resource.name = "GitLab QA"
  end

shirt.brand # => OK!

shirt.project.visit!

shirt.brand # => OK!

The attribute will be stored in the instance therefore all the following calls will be fine, using the data previously constructed. If we think that this might be too brittle, we could eagerly construct the data right before ending fabrication:

module QA
  module Resource
    class Shirt < Base
      # ... same as before

      def fabricate!
        project.visit!

        Page::Project::Show.perform do |project_show|
          project_show.go_to_new_shirt
        end

        Page::Shirt::New.perform do |shirt_new|
          shirt_new.set_name(name)
          shirt_new.create_shirt!
        end

        populate(:brand) # Eagerly construct the data
      end
    end
  end
end

The populate method will iterate through its arguments and call each attribute respectively. Here populate(:brand) has the same effect as just brand. Using the populate method makes the intention clearer.

With this, it will make sure we construct the data right after we create the shirt. The drawback is that this will always construct the data when the resource is fabricated even if we don’t need to use the data.

Alternatively, we could just make sure we’re on the right page before constructing the brand data:

module QA
  module Resource
    class Shirt < Base
      attr_accessor :name

      attribute :project do
        Project.fabricate! do |resource|
          resource.name = 'project-to-create-a-shirt'
        end
      end

      # Attribute populated from the Browser UI (using the block)
      attribute :brand do
        back_url = current_url
        visit!

        Page::Shirt::Show.perform do |shirt_show|
          shirt_show.fetch_brand_from_page
        end

        visit(back_url)
      end

      # ... same as before
    end
  end
end

This will make sure it’s on the shirt page before constructing brand, and move back to the previous page to avoid breaking the state.

Define an attribute based on an API response

Sometimes, you want to define a resource attribute based on the API response from its GET or POST request. For instance, if the creation of a shirt via the API returns

{
  brand: 'a-brand-new-brand',
  style: 't-shirt',
  materials: [[:cotton, 80], [:polyamide, 20]]
}

you may want to store style as-is in the resource, and fetch the first value of the first materials item in a main_fabric attribute.

Let’s take the Shirt resource class, and define a :style and a :main_fabric attributes:

module QA
  module Resource
    class Shirt < Base
      # ... same as before

      # @style from the instance if present,
      # or fetched from the API response if present,
      # or a QA::Resource::Base::NoValueError is raised otherwise
      attribute :style

      # If @main_fabric is not present,
      # and if the API does not contain this field, this block will be
      # used to construct the value based on the API response, and
      # store the result in @main_fabric
      attribute :main_fabric do
        api_response.&dig(:materials, 0, 0)
      end

      # ... same as before
    end
  end
end

Notes on attributes precedence:

  • resource instance variables have the highest precedence
  • attributes from the API response take precedence over attributes from the block (usually from Browser UI)
  • attributes without a value will raise a QA::Resource::Base::NoValueError error

Creating resources in your tests

To create a resource in your tests, you can call the .fabricate! method on the resource class. Note that if the resource class supports API fabrication, this will use this fabrication by default.

Here is an example that will use the API fabrication method under the hood since it’s supported by the Shirt resource class:

my_shirt = Resource::Shirt.fabricate! do |shirt|
  shirt.name = 'my-shirt'
end

expect(page).to have_text(my_shirt.name) # => "my-shirt" from the resource's instance variable
expect(page).to have_text(my_shirt.brand) # => "a-brand-new-brand" from the API response
expect(page).to have_text(my_shirt.style) # => "t-shirt" from the API response
expect(page).to have_text(my_shirt.main_fabric) # => "cotton" from the API response via the block

If you explicitly want to use the Browser UI fabrication method, you can call the .fabricate_via_browser_ui! method instead:

my_shirt = Resource::Shirt.fabricate_via_browser_ui! do |shirt|
  shirt.name = 'my-shirt'
end

expect(page).to have_text(my_shirt.name) # => "my-shirt" from the resource's instance variable
expect(page).to have_text(my_shirt.brand) # => the brand name fetched from the `Page::Shirt::Show` page via the block
expect(page).to have_text(my_shirt.style) # => QA::Resource::Base::NoValueError will be raised because no API response nor a block is provided
expect(page).to have_text(my_shirt.main_fabric) # => QA::Resource::Base::NoValueError will be raised because no API response and the block didn't provide a value (because it's also based on the API response)

You can also explicitly use the API fabrication method, by calling the .fabricate_via_api! method:

my_shirt = Resource::Shirt.fabricate_via_api! do |shirt|
  shirt.name = 'my-shirt'
end

In this case, the result will be similar to calling Resource::Shirt.fabricate!.

Where to ask for help?

If you need more information, ask for help on #quality channel on Slack (internal, GitLab Team only).

If you are not a Team Member, and you still need help to contribute, please open an issue in GitLab CE issue tracker with the ~QA label.