--- stage: none group: unassigned info: Any user with at least the Maintainer role can merge updates to this content. For details, see https://docs.gitlab.com/ee/development/development_processes.html#development-guidelines-review. --- # Page objects in GitLab QA In GitLab QA we are using a known pattern, called _Page Objects_. This means that we have built an abstraction for all pages in GitLab that we use to drive GitLab QA scenarios. Whenever we do something on a page, like filling in a form or selecting a button, we do that only through a page object associated with this area of GitLab. For example, when GitLab QA test harness signs in into GitLab, it needs to fill in user login and user password. To do that, we have a class, called `Page::Main::Login` and `sign_in_using_credentials` methods, that is the only piece of the code, that reads the `user_login` and `user_password` fields. ## Why do we need that? We need page objects because we need to reduce duplication and avoid problems whenever someone changes some selectors in the GitLab source code. Imagine that we have a hundred specs in GitLab QA, and we need to sign into GitLab each time, before we make assertions. Without a page object, one would need to rely on volatile helpers or invoke Capybara methods directly. Imagine invoking `fill_in :user_login` in every `*_spec.rb` file / test example. When someone later changes `t.text_field :login` in the view associated with this page to `t.text_field :username` it generates a different field identifier, what would effectively break all tests. Because we are using `Page::Main::Login.perform(&:sign_in_using_credentials)` everywhere, when we want to sign in to GitLab, the page object is the single source of truth, and we must update `fill_in :user_login` to `fill_in :user_username` only in one place. ## What problems did we have in the past? We do not run QA tests for every commit, because of performance reasons, and the time it would take to build packages and test everything. That is why when someone changes `t.text_field :login` to `t.text_field :username` in the _new session_ view we don't know about this change until our GitLab QA nightly pipeline fails, or until someone triggers `package-and-qa` action in their merge request. Such a change would break all tests. We call this problem a _fragile tests problem_. To make GitLab QA more reliable and robust, we had to solve this problem by introducing coupling between GitLab CE / EE views and GitLab QA. ## How did we solve fragile tests problem? Currently, when you add a new `Page::Base` derived class, you must also define all selectors that your page objects depend on. Whenever you push your code to CE / EE repository, `qa:selectors` sanity test job runs as a part of a CI pipeline. This test validates all page objects that we have implemented in `qa/page` directory. When it fails, it notifies you about missing or invalid views/selectors definition. ## How to properly implement a page object? We have built a DSL to define coupling between a page object and GitLab views it is actually implemented by. See an example below. ```ruby module Page module Main class Login < Page::Base view 'app/views/devise/passwords/edit.html.haml' do element :password_field element :password_confirmation element :change_password_button end view 'app/views/devise/sessions/_new_base.html.haml' do element :login_field element :password_field element :sign_in_button end # ... end end end ``` ### Defining Elements The `view` DSL method corresponds to the Rails view, partial, or Vue component that renders the elements. The `element` DSL method in turn declares an element for which a corresponding `testid=element_name` data attribute must be added, if not already, to the view file. You can also define a value (String or Regexp) to match to the actual view code but **this is deprecated** in favor of the above method for two reasons: - Consistency: there is only one way to define an element - Separation of concerns: QA uses dedicated `data-qa-*` attributes instead of reusing code or classes used by other components (for example, `js-*` classes etc.) ```ruby view 'app/views/my/view.html.haml' do ### Good ### # Implicitly require the CSS selector `[data-testid="logout_button"]` to be present in the view element :logout_button ### Bad ### ## This is deprecated and forbidden by the `QA/ElementWithPattern` RuboCop cop. # Require `f.submit "Sign in"` to be present in `my/view.html.haml element :my_button, 'f.submit "Sign in"' # rubocop:disable QA/ElementWithPattern ## This is deprecated and forbidden by the `QA/ElementWithPattern` RuboCop cop. # Match every line in `my/view.html.haml` against # `/link_to .* "My Profile"/` regexp. element :profile_link, /link_to .* "My Profile"/ # rubocop:disable QA/ElementWithPattern end ``` ### Adding Elements to a View Given the following elements... ```ruby view 'app/views/my/view.html.haml' do element :login_field element :password_field element :sign_in_button end ``` To add these elements to the view, you must change the Rails view, partial, or Vue component by adding a `data-testid` attribute for each element defined. In our case, `data-testid="login_field"`, `data-testid="password_field"` and `data-testid="sign_in_button"` `app/views/my/view.html.haml` ```haml = f.text_field :login, class: "form-control top", autofocus: "autofocus", autocapitalize: "off", autocorrect: "off", required: true, title: "This field is required.", data: { testid: 'login_field' } = f.password_field :password, class: "form-control bottom", required: true, title: "This field is required.", data: { testid: 'password_field' } = f.submit "Sign in", class: "btn btn-confirm", data: { testid: 'sign_in_button' } ``` Things to note: - The name of the element and the `data-testid` must match and be either snake cased or kebab cased - If the element appears on the page unconditionally, add `required: true` to the element. See [Dynamic element validation](dynamic_element_validation.md) - You should not see `data-qa-selector` classes in Page Objects. We should use the [`data-testid`](#data-testid-vs-data-qa-selector) method of definition ### `data-testid` vs `data-qa-selector` > Introduced in GitLab 16.1 Any existing `data-qa-selector` class should be considered deprecated and we should use the `data-testid` method of definition. ### Dynamic element selection > Introduced in GitLab 12.5 A common occurrence in automated testing is selecting a single "one-of-many" element. In a list of several items, how do you differentiate what you are selecting on? The most common workaround for this is via text matching. Instead, a better practice is by matching on that specific element by a unique identifier, rather than by text. We got around this by adding the `data-qa-*` extensible selection mechanism. #### Examples **Example 1** Given the following Rails view (using GitLab Issues as an example): ```haml %ul.issues-list - @issues.each do |issue| %li.issue{data: { testid: 'issue', qa_issue_title: issue.title } }= link_to issue ``` We can select on that specific issue by matching on the Rails model. ```ruby class Page::Project::Issues::Index < Page::Base def has_issue?(issue) has_element?(:issue, issue_title: issue) end end ``` In our test, we can validate that this particular issue exists. ```ruby describe 'Issue' do it 'has an issue titled "hello"' do Page::Project::Issues::Index.perform do |index| expect(index).to have_issue('hello') end end end ``` **Example 2** *By an index...* ```haml %ol - @some_model.each_with_index do |model, idx| %li.model{ data: { testid: 'model', qa_index: idx } } ``` ```ruby expect(the_page).to have_element(:model, index: 1) #=> select on the first model that appears in the list ``` ### Exceptions In some cases, it might not be possible or worthwhile to add a selector. Some UI components use external libraries, including some maintained by third parties. Even if a library is maintained by GitLab, the selector sanity test only runs on code within the GitLab project, so it's not possible to specify the path for the view for code in a library. In such rare cases it's reasonable to use CSS selectors in page object methods, with a comment explaining why an `element` can't be added. ### Define Page concerns Some pages share common behaviors, and/or are prepended with EE-specific modules that adds EE-specific methods. These modules must: 1. Extend from the `QA::Page::PageConcern` module, with `extend QA::Page::PageConcern`. 1. Override the `self.prepended` method if they need to `include`/`prepend` other modules themselves, and/or define `view` or `elements`. 1. Call `super` as the first thing in `self.prepended`. 1. Include/prepend other modules and define their `view`/`elements` in a `base.class_eval` block to ensure they're defined in the class that prepends the module. These steps ensure the sanity selectors check detect problems properly. For example, `qa/qa/ee/page/merge_request/show.rb` adds EE-specific methods to `qa/qa/page/merge_request/show.rb` (with `QA::Page::MergeRequest::Show.prepend_mod_with('Page::MergeRequest::Show', namespace: QA)`) and following is how it's implemented (only showing the relevant part and referring to the 4 steps described above with inline comments): ```ruby module QA module EE module Page module MergeRequest module Show extend QA::Page::PageConcern # 1. def self.prepended(base) # 2. super # 3. base.class_eval do # 4. prepend Page::Component::LicenseManagement view 'app/assets/javascripts/vue_merge_request_widget/components/states/sha_mismatch.vue' do element :head_mismatch, "The source branch HEAD has recently changed." end [...] end end end end end end end ``` ## Running the test locally During development, you can run the `qa:selectors` test by running ```shell bin/qa Test::Sanity::Selectors ``` from within the `qa` directory. ## Where to ask for help? If you need more information, ask for help on `#test-platform` channel on Slack (internal, GitLab Team only). If you are not a Team Member, and you still need help to contribute, open an issue in GitLab CE issue tracker with the `~QA` label.