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diff --git a/doc/development/testing_guide/end_to_end/page_objects.md b/doc/development/testing_guide/end_to_end/page_objects.md new file mode 100644 index 00000000000..d0de33892c4 --- /dev/null +++ b/doc/development/testing_guide/end_to_end/page_objects.md @@ -0,0 +1,134 @@ +# 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 GitLab pages that we use +to drive GitLab QA scenarios. Whenever we do something on a page, like filling +in a form, or clicking 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 a user login and user password. In order 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 has knowledge about `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 GitLab's 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 will generate a different field +identifier, what would effectively break all tests. + +Because we are using `Page::Main::Login.act { sign_in_using_credentials }` +everywhere, when we want to sign into GitLab, the page object is the single +source of truth, and we will need to update `fill_in :user_login` +to `fill_in :user_username` only in a 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 won't know about this +change until our GitLab QA nightly pipeline fails, or until someone triggers +`package-and-qa` action in their merge request. + +Obviously such a change would break all tests. We call this problem a _fragile +tests problem_. + +In order 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 will also need to +define all selectors that your page objects depends on. + +Whenever you push your code to CE / EE repository, `qa:selectors` sanity test +job is going to be run as a part of a CI pipeline. + +This test is going to validate all page objects that we have implemented in +`qa/page` directory. When it fails, you will be notified 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 +``` + +The `view` DSL method declares the filename of the view where an +`element` is implemented. + +The `element` DSL method in turn declares an element for which a corresponding +`qa-element-name-dasherized` CSS class need to be added 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 CSS classes instead of reusing code + or classes used by other components (e.g. `js-*` classes etc.) + +```ruby +view 'app/views/my/view.html.haml' do + # Implicitly require `.qa-logout-button` CSS class to be present in the view + element :logout_button + + ## 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 +``` + +## 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 `#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. |