Merge branch 'docs/qa/gb/document-integration-tests-in-merge-requests' into 'master'

Add docs about end-to-end testing / GitLab QA tests

Closes #39637

See merge request gitlab-org/gitlab-ce!16043

doc/development/testing_guide/end_to_end_tests.md

+# End-to-End Testing
+
+## What is End-to-End testing?
+
+End-to-End testing is a strategy used to check whether your application works
+as expected across entire software stack and architecture, including
+integration of all microservices and components that are supposed to work
+together.
+
+## How do we test GitLab?
+
+We use [Omnibus GitLab][omnibus-gitlab] to build GitLab packages and then we
+test these packages using [GitLab QA][gitlab-qa] project, which is entirely
+black-box, click-driven testing framework.
+
+### Testing nightly builds
+
+We run scheduled pipeline each night to test nightly builds created by Omnibus.
+You can find these nightly pipelines at [GitLab QA pipelines page][gitlab-qa-pipelines].
+
+### Testing code in merge requests
+
+It is possible to run end-to-end tests (eventually being run within a
+[GitLab QA pipeline][gitlab-qa-pipelines]) for a merge request by triggering
+the `package-qa` manual action, that should be present in a merge request
+widget.
+
+Mmanual action that starts end-to-end tests is also available in merge requests
+in Omnibus GitLab project.
+
+Below you can read more about how to use it and how does it work.
+
+#### How does it work?
+
+Currently, we are using _multi-project pipeline_-like approach to run QA
+pipelines.
+
+1. Developer triggers a manual action, that can be found in CE and EE merge
+requests. This starts a chain of pipelines in multiple projects.
+
+1. The script being executed triggers a pipeline in GitLab Omnibus and waits
+for the resulting status. We call this a _status attribution_.
+
+1. GitLab packages are being built in Omnibus pipeline. Packages are going to be
+pushed to Container Registry.
+
+1. When packages are ready, and available in the registry, a final step in the
+pipeline, that is now running in Omnibus, triggers a new pipeline in the GitLab
+QA project. It also waits for a resulting status.
+
+1. GitLab QA pulls images from the registry, spins-up containers and runs tests
+against a test environment that has been just orchestrated by the `gitlab-qa`
+tool.
+
+1. The result of the GitLab QA pipeline is being propagated upstream, through
+Omnibus, back to CE / EE merge request.
+
+#### How do I write tests?
+
+In order to write new tests, you first need to learn more about GitLab QA
+architecture. See the [documentation about it][gitlab-qa-architecture] in
+GitLab QA project.
+
+Once you decided where to put test environment orchestration scenarios and
+instance specs, take a look at the [relevant documentation][instance-qa-readme]
+and examples in [the `qa/` directory][instance-qa-examples].
+
+## Where can I ask for help?
+
+You can ask question in the `#qa` channel on Slack (GitLab internal) or you can
+find an issue you would like to work on in [the issue tracker][gitlab-qa-issues]
+and start a new discussion there.
+
+[omnibus-gitlab]: https://gitlab.com/gitlab-org/omnibus-gitlab
+[gitlab-qa]: https://gitlab.com/gitlab-org/gitlab-qa
+[gitlab-qa-pipelines]: https://gitlab.com/gitlab-org/gitlab-qa/pipelines
+[gitlab-qa-architecture]: https://gitlab.com/gitlab-org/gitlab-qa/blob/master/docs/architecture.md
+[gitlab-qa-issues]: https://gitlab.com/gitlab-org/gitlab-qa/issues
+[instance-qa-readme]: https://gitlab.com/gitlab-org/gitlab-ce/tree/master/qa/README.md
+[instance-qa-examples]: https://gitlab.com/gitlab-org/gitlab-ce/tree/master/qa/qa

doc/development/testing_guide/index.md

@@ -65,6 +65,13 @@ Everything you should know about how to test Rake tasks.
 
 ---
 
+## [End-to-end tests](end_to_end_tests.md)
+
+Everything you should know about how to run end-to-end tests using
+[GitLab QA][gitlab-qa] testing framework.
+
+---
+
 ## Spinach (feature) tests
 
 GitLab [moved from Cucumber to Spinach](https://github.com/gitlabhq/gitlabhq/pull/1426)
@@ -89,3 +96,4 @@ test should be re-implemented using RSpec instead.
 [Capybara]: https://github.com/teamcapybara/capybara
 [Karma]: http://karma-runner.github.io/
 [Jasmine]: https://jasmine.github.io/
+[gitlab-qa]: https://gitlab.com/gitlab-org/gitlab-qa

doc/development/testing_guide/testing_levels.md

@@ -121,6 +121,9 @@ running feature tests (i.e. using Capybara) against it.
 The actual test scenarios and steps are [part of GitLab Rails] so that they're
 always in-sync with the codebase.
 
+Read a separate document about [end-to-end tests](end_to_end_tests.md) to
+learn more.
+
 [multiple pieces]: ../architecture.md#components
 [GitLab Shell]: https://gitlab.com/gitlab-org/gitlab-shell
 [GitLab Workhorse]: https://gitlab.com/gitlab-org/gitlab-workhorse