First pass at a Testing styleguide

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+# Testing Standards and Style Guidelines
+
+This guide outlines standards and best practices for automated testing of GitLab
+CE and EE.
+
+It is meant to be an _extension_ of the [thoughtbot testing
+styleguide](https://github.com/thoughtbot/guides/tree/master/style/testing). If
+this guide defines a rule that contradicts the thoughtbot guide, this guide
+takes precedence. Some guidelines may be repeated verbatim to stress their
+importance.
+
+## Factories
+
+GitLab uses [factory_girl] as a test
+fixture replacement.
+
+- Factory definitions live in `spec/factories/`, named using the pluralization
+  of their corresponding model (`User` factories are defined in `users.rb`).
+- There should be only one top-level factory definition per file.
+- Make use of [Traits] to clean up definitions and usages.
+- When defining a factory, don't define attributes that are not required for the
+  resulting record to pass validation.
+- When instantiating from a factory, don't supply extraneous attributes that
+  aren't required by the test.
+
+[factory_girl]: https://github.com/thoughtbot/factory_girl
+[Traits]: http://www.rubydoc.info/gems/factory_girl/file/GETTING_STARTED.md#Traits
+
+## JavaScript
+
+GitLab uses [Teaspoon] to run its [Jasmine] JavaScript specs. They can be run on
+the command line via `bundle exec teaspoon`, or via a web browser at
+`http://localhost:3000/teaspoon` when the Rails server is running.
+
+- JavaScript tests live in `spec/javascripts/`, matching the folder structure of
+  `app/assets/javascripts/`: `app/assets/javascripts/behaviors/autosize.js.coffee` has a corresponding
+  `spec/javascripts/behaviors/autosize_spec.js.coffee` file.
+- Haml fixtures required for JavaScript tests live in
+  `spec/javascripts/fixtures`. They should contain the bare minimum amount of
+  markup necessary for the test.
+
+  > **Warning:** Keep in mind that a Rails view may change and
+  invalidate your test, but everything will still pass because your fixture
+  doesn't reflect the latest view.
+
+- Keep in mind that in a CI environment, these tests are run in a headless
+  browser and you will not have access to certain APIs, such as
+  [`Notification`](https://developer.mozilla.org/en-US/docs/Web/API/notification),
+  which will have to be stubbed.
+
+[Teaspoon]: https://github.com/modeset/teaspoon
+[Jasmine]: https://github.com/jasmine/jasmine
+
+## RSpec
+
+### General Guidelines
+
+- Use a single, top-level `describe ClassName` block.
+- Use `described_class` instead of repeating the class name being described.
+- Use `.method` to describe class methods and `#method` to describe instance
+  methods.
+- Use `context` to test branching logic.
+- Don't `describe` symbols (see [Gotchas](gotchas.md#dont-describe-symbols)).
+- Prefer `not_to` to `to_not`.
+- Try to match the ordering of tests to the ordering within the class.
+
+### Test speed
+
+GitLab has a massive test suite that, without parallelization, can take more
+than an hour to run. It's important that we make an effort to write tests that
+are accurate and effective _as well as_ fast.
+
+Here are some things to keep in mind regarding test performance:
+
+- `double` and `spy` are faster than `FactoryGirl.build(...)`
+- `FactoryGirl.build(...)` and `.build_stubbed` are faster than `.create`.
+- Don't `create` an object when `build`, `build_stubbed`, `attributes_for`,
+  `spy`, or `double` will do. Database persistence is slow!
+- Use `create(:empty_project)` instead of `create(:project)` when you don't need
+  the underlying repository. Filesystem operations are slow!
+- Don't mark a feature as requiring JavaScript (through `@javascript` in
+  Spinach or `js: true` in RSpec) unless it's _actually_ required for the test
+  to be valid. Headless browser testing is slow!
+
+### Features / Integration
+
+- Feature specs live in `spec/features/` and should be named
+  `ROLE_ACTION_spec.rb`, such as `user_changes_password_spec.rb`.
+- Use only one `feature` block per feature spec file.
+- Use scenario titles that describe the success and failure paths.
+- Avoid scenario titles that add no information, such as "successfully."
+- Avoid scenario titles that repeat the feature title.
+
+## Spinach (feature) tests
+
+GitLab [moved from Cucumber to Spinach](https://github.com/gitlabhq/gitlabhq/pull/1426)
+for its feature/integration tests in September 2012.
+
+As of March 2016, we are [trying to avoid adding new Spinach
+tests](https://gitlab.com/gitlab-org/gitlab-ce/issues/14121) going forward,
+opting for [RSpec feature](#features-integration) specs.
+
+Adding new Spinach scenarios is acceptable _only if_ the new scenario requires
+no more than one new `step` definition. If more than that is required, the
+test should be re-implemented using RSpec instead.