134 lines
5 KiB
Markdown
134 lines
5 KiB
Markdown
# Page objects in GitLab QA
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In GitLab QA we are using a known pattern, called _Page Objects_.
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This means that we have built an abstraction for all GitLab pages that we use
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to drive GitLab QA scenarios. Whenever we do something on a page, like filling
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in a form, or clicking a button, we do that only through a page object
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associated with this area of GitLab.
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For example, when GitLab QA test harness signs in into GitLab, it needs to fill
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in a user login and user password. In order to do that, we have a class, called
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`Page::Main::Login` and `sign_in_using_credentials` methods, that is the only
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piece of the code, that has knowledge about `user_login` and `user_password`
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fields.
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## Why do we need that?
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We need page objects, because we need to reduce duplication and avoid problems
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whenever someone changes some selectors in GitLab's source code.
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Imagine that we have a hundred specs in GitLab QA, and we need to sign into
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GitLab each time, before we make assertions. Without a page object one would
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need to rely on volatile helpers or invoke Capybara methods directly. Imagine
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invoking `fill_in :user_login` in every `*_spec.rb` file / test example.
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When someone later changes `t.text_field :login` in the view associated with
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this page to `t.text_field :username` it will generate a different field
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identifier, what would effectively break all tests.
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Because we are using `Page::Main::Login.act { sign_in_using_credentials }`
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everywhere, when we want to sign into GitLab, the page object is the single
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source of truth, and we will need to update `fill_in :user_login`
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to `fill_in :user_username` only in a one place.
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## What problems did we have in the past?
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We do not run QA tests for every commit, because of performance reasons, and
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the time it would take to build packages and test everything.
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That is why when someone changes `t.text_field :login` to
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`t.text_field :username` in the _new session_ view we won't know about this
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change until our GitLab QA nightly pipeline fails, or until someone triggers
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`package-and-qa` action in their merge request.
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Obviously such a change would break all tests. We call this problem a _fragile
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tests problem_.
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In order to make GitLab QA more reliable and robust, we had to solve this
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problem by introducing coupling between GitLab CE / EE views and GitLab QA.
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## How did we solve fragile tests problem?
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Currently, when you add a new `Page::Base` derived class, you will also need to
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define all selectors that your page objects depends on.
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Whenever you push your code to CE / EE repository, `qa:selectors` sanity test
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job is going to be run as a part of a CI pipeline.
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This test is going to validate all page objects that we have implemented in
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`qa/page` directory. When it fails, you will be notified about missing
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or invalid views / selectors definition.
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## How to properly implement a page object?
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We have built a DSL to define coupling between a page object and GitLab views
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it is actually implemented by. See an example below.
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```ruby
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module Page
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module Main
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class Login < Page::Base
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view 'app/views/devise/passwords/edit.html.haml' do
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element :password_field
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element :password_confirmation
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element :change_password_button
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end
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view 'app/views/devise/sessions/_new_base.html.haml' do
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element :login_field
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element :password_field
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element :sign_in_button
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end
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# ...
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end
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end
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```
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The `view` DSL method declares the filename of the view where an
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`element` is implemented.
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The `element` DSL method in turn declares an element for which a corresponding
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`qa-element-name-dasherized` CSS class need to be added to the view file.
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You can also define a value (String or Regexp) to match to the actual view
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code but **this is deprecated** in favor of the above method for two reasons:
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- Consistency: there is only one way to define an element
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- Separation of concerns: QA uses dedicated CSS classes instead of reusing code
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or classes used by other components (e.g. `js-*` classes etc.)
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```ruby
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view 'app/views/my/view.html.haml' do
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# Implicitly require `.qa-logout-button` CSS class to be present in the view
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element :logout_button
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## This is deprecated and forbidden by the `QA/ElementWithPattern` RuboCop cop.
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# Require `f.submit "Sign in"` to be present in `my/view.html.haml
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element :my_button, 'f.submit "Sign in"' # rubocop:disable QA/ElementWithPattern
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## This is deprecated and forbidden by the `QA/ElementWithPattern` RuboCop cop.
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# Match every line in `my/view.html.haml` against
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# `/link_to .* "My Profile"/` regexp.
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element :profile_link, /link_to .* "My Profile"/ # rubocop:disable QA/ElementWithPattern
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end
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```
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## Running the test locally
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During development, you can run the `qa:selectors` test by running
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```shell
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bin/qa Test::Sanity::Selectors
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```
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from within the `qa` directory.
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## Where to ask for help?
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If you need more information, ask for help on `#quality` channel on Slack
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(internal, GitLab Team only).
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If you are not a Team Member, and you still need help to contribute, please
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open an issue in GitLab CE issue tracker with the `~QA` label.
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