Guidelines for implementing Enterprise Edition features

Place code in ee/: Put all Enterprise Edition (EE) inside the ee/ top-level directory. The rest of the code must be as close to the Community Edition (CE) files as possible.
Write tests: As with any code, EE features must have good test coverage to prevent regressions. All ee/ code must have corresponding tests in ee/.
Write documentation.: Add documentation to the doc/ directory. Describe the feature and include screenshots, if applicable. Indicate what editions the feature applies to.

Submit a MR to the www-gitlab-com project.: Add the new feature to the EE features list.

SaaS-only feature

Use the following guidelines when you develop a feature that is only applicable for SaaS (for example, a CustomersDot integration).

In general, features should be provided for both SaaS and self-managed deployments. However, there are cases when a feature should only be available on SaaS and this guide will help show how that is accomplished.

It is recommended you use Gitlab::Saas.feature_available?. This enables context rich definitions around the reason the feature is SaaS-only.

Implementing a SaaS-only feature with `Gitlab::Saas.feature_available?`

Adding to the FEATURES constant

See the namespacing concepts guide for help in naming a new SaaS-only feature.

Add the new feature to FEATURE in ee/lib/ee/gitlab/saas.rb.

FEATURES = %i[purchases_additional_minutes some_domain_new_feature_name].freeze

Use the new feature in code with Gitlab::Saas.feature_available?(:some_domain_new_feature_name).

SaaS-only feature definition and validation

This process is meant to ensure consistent SaaS feature usage in the codebase. All SaaS features must:

Be known. Only use SaaS features that are explicitly defined.
Have an owner.

All SaaS features are self-documented in YAML files stored in:

ee/config/saas_features

Each SaaS feature is defined in a separate YAML file consisting of a number of fields:

Field	Required	Description
`name`	yes	Name of the SaaS feature.
`introduced_by_url`	no	The URL to the merge request that introduced the SaaS feature.
`milestone`	no	Milestone in which the SaaS feature was created.
`group`	no	The group that owns the feature flag.

Create a new SaaS feature file definition

The GitLab codebase provides bin/saas-feature.rb, a dedicated tool to create new SaaS feature definitions. The tool asks various questions about the new SaaS feature, then creates a YAML definition in ee/config/saas_features.

Only SaaS features that have a YAML definition file can be used when running the development or testing environments.

❯ bin/saas-feature my_saas_feature
You picked the group 'group::acquisition'

>> URL of the MR introducing the SaaS feature (enter to skip and let Danger provide a suggestion directly in the MR):
?> https://gitlab.com/gitlab-org/gitlab/-/merge_requests/38602
create ee/config/saas_features/my_saas_feature.yml
---
name: my_saas_feature
introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/38602
milestone: '16.8'
group: group::acquisition

Opting out of a SaaS-only feature on another SaaS instance (JiHu)

Prepend the ee/lib/ee/gitlab/saas.rb module and override the Gitlab::Saas.feature_available? method.

JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end

Do not use SaaS-only features for functionality in CE

Gitlab::Saas.feature_available? must not appear in CE. See extending CE with EE guide.

SaaS-only features in tests

Introducing a SaaS-only feature into the codebase creates an additional code path that should be tested. It is strongly advised to include automated tests for all code affected by a SaaS-only feature, both when enabled and disabled to ensure the feature works properly.

To enable a SaaS-only feature in a test, use the stub_saas_features helper. For example, to globally disable the purchases_additional_minutes feature flag in a test:

stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false

A common pattern of testing both paths looks like:

it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end

Simulate a SaaS instance

If you're developing locally and need your instance to simulate the SaaS (GitLab.com) version of the product:

Export this environment variable:
```
export GITLAB_SIMULATE_SAAS=1
```
There are many ways to pass an environment variable to your local GitLab instance. For example, you can create an env.runit file in the root of your GDK with the above snippet.
Enable Allow use of licensed EE features to make licensed EE features available to projects only if the project namespace's plan includes the feature.
1. On the left sidebar, at the bottom, select Admin.
2. On the left sidebar, select Settings > General.
3. Expand Account and limit.
4. Select the Allow use of licensed EE features checkbox.
5. Select Save changes.
Ensure the group you want to test the EE feature for is actually using an EE plan:
1. On the left sidebar, at the bottom, select Admin.
2. On the left sidebar, select Overview > Groups.
3. Identify the group you want to modify, and select Edit.
4. Scroll to Permissions and group features. For Plan, select Ultimate.
5. Select Save changes.

Here's a 📺 video demonstrating how to do the steps above.

Implement a new EE feature

If you're developing a GitLab Premium or GitLab Ultimate licensed feature, use these steps to add your new feature or extend it.

GitLab license features are added to ee/app/models/gitlab_subscriptions/features.rb. To determine how to modify this file, first discuss how your feature fits into our licensing with your Product Manager.

Use the following questions to guide you:

Is this a new feature, or are you extending an existing licensed feature?
- If your feature already exists, you don't have to modify features.rb, but you must locate the existing feature identifier to guard it.
- If this is a new feature, decide on an identifier, such as my_feature_name, to add to the features.rb file.
Is this a GitLab Premium or GitLab Ultimate feature?
- Based on the plan you choose to use the feature in, add the feature identifier to PREMIUM_FEATURES or ULTIMATE_FEATURES.
Will this feature be available globally (system-wide for the GitLab instance)?
- Features such as Geo and Database Load Balancing are used by the entire instance and cannot be restricted to individual user namespaces. These features are defined in the instance license. Add these features to GLOBAL_FEATURES.

Guard your EE feature

A licensed feature can only be available to licensed users. You must add a check or guard to determine if users have access to the feature.

To guard your licensed feature:

Locate your feature identifier in ee/app/models/gitlab_subscriptions/features.rb.

Use the following methods, where my_feature_name is your feature identifier:

In a project context:

my_project.licensed_feature_available?(:my_feature_name) # true if available for my_project

In a group or user namespace context:

my_group.licensed_feature_available?(:my_feature_name) # true if available for my_group

For a global (system-wide) feature:

License.feature_available?(:my_feature_name)  # true if available in this instance

Optional. If your global feature is also available to namespaces with a paid plan, combine two feature identifiers to allow both administrators and group users. For example:
```
License.feature_available?(:my_feature_name) || group.licensed_feature_available?(:my_feature_name_for_namespace) # Both admins and group members can see this EE feature
```

Simulate a CE instance when unlicensed

After the implementation of GitLab CE features to work with unlicensed EE instance GitLab Enterprise Edition works like GitLab Community Edition when no license is active.

CE specs should remain untouched as much as possible and extra specs should be added for EE. Licensed features can be stubbed using the spec helper stub_licensed_features in EE::LicenseHelpers.

You can force GitLab to act as CE by either deleting the ee/ directory or by setting the FOSS_ONLY environment variable to something that evaluates as true. The same works for running tests (for example FOSS_ONLY=1 yarn jest).

Simulate a CE instance with a licensed GDK

To simulate a CE instance without deleting the license in a GDK:

Create an env.runit file in the root of your GDK with the line:
```
export FOSS_ONLY=1
```

Then restart the GDK:

gdk restart rails && gdk restart webpack

Remove the line in env.runit if you want to revert back to an EE installation, and repeat step 2.

Run feature specs as CE

When running feature specs as CE, you should ensure that the edition of backend and frontend match. To do so:

Set the FOSS_ONLY=1 environment variable:
```
export FOSS_ONLY=1
```
Start GDK:
```
gdk start
```

Run feature specs:

bin/rspec spec/features/<path_to_your_spec>

Run CI pipelines in a FOSS context

By default, merge request pipelines for development run in an EE-context only. If you are developing features that differ between FOSS and EE, you may wish to run pipelines in a FOSS context as well.

To run pipelines in both contexts, add the ~"pipeline:run-as-if-foss" label to the merge request.

See the As-if-FOSS jobs and cross project downstream pipeline pipelines documentation for more information.

Separation of EE code in the backend

EE-only features

If the feature being developed is not present in any form in CE, we don't need to put the code under the EE namespace. For example, an EE model could go into: ee/app/models/awesome.rb using Awesome as the class name. This is applied not only to models. Here's a list of other examples:

ee/app/controllers/foos_controller.rb
ee/app/finders/foos_finder.rb
ee/app/helpers/foos_helper.rb
ee/app/mailers/foos_mailer.rb
ee/app/models/foo.rb
ee/app/policies/foo_policy.rb
ee/app/serializers/foo_entity.rb
ee/app/serializers/foo_serializer.rb
ee/app/services/foo/create_service.rb
ee/app/validators/foo_attr_validator.rb
ee/app/workers/foo_worker.rb
ee/app/views/foo.html.haml
ee/app/views/foo/_bar.html.haml
ee/config/initializers/foo_bar.rb

This works because for every path in the CE eager-load/auto-load path, we add the same ee/-prepended path in config/application.rb. This also applies to views.

Testing EE-only backend features

To test an EE class that doesn't exist in CE, create the spec file as you usually would in the ee/spec directory, but without the second ee/ subdirectory. For example, a class ee/app/models/vulnerability.rb would have its tests in ee/spec/models/vulnerability_spec.rb.

By default, licensed features are disabled for specs in specs/. Specs in the ee/spec directory have Starter license initialized by default.

To effectively test your feature you must explicitly enable the feature using the stub_licensed_features helper, for example:

  stub_licensed_features(my_awesome_feature_name: true)

Extend CE features with EE backend code

For features that build on existing CE features, write a module in the EE namespace and inject it in the CE class, on the last line of the file that the class resides in. This makes conflicts less likely to happen during CE to EE merges because only one line is added to the CE class - the line that injects the module. For example, to prepend a module into the User class you would use the following approach:

class User < ActiveRecord::Base
  # ... lots of code here ...
end

User.prepend_mod

Do not use methods such as prepend, extend, and include. Instead, use prepend_mod, extend_mod, or include_mod. These methods will try to find the relevant EE module by the name of the receiver module, for example;

module Vulnerabilities
  class Finding
    #...
  end
end

Vulnerabilities::Finding.prepend_mod

will prepend the module named ::EE::Vulnerabilities::Finding.

If the extending module does not follow this naming convention, you can also provide the module name by using prepend_mod_with, extend_mod_with, or include_mod_with. These methods take a String containing the full module name as the argument, not the module itself, like so;

class User
  #...
end

User.prepend_mod_with('UserExtension')

Since the module would require an EE namespace, the file should also be put in an ee/ sub-directory. For example, we want to extend the user model in EE, so we have a module called ::EE::User put inside ee/app/models/ee/user.rb.

This is also not just applied to models. Here's a list of other examples:

ee/app/controllers/ee/foos_controller.rb
ee/app/finders/ee/foos_finder.rb
ee/app/helpers/ee/foos_helper.rb
ee/app/mailers/ee/foos_mailer.rb
ee/app/models/ee/foo.rb
ee/app/policies/ee/foo_policy.rb
ee/app/serializers/ee/foo_entity.rb
ee/app/serializers/ee/foo_serializer.rb
ee/app/services/ee/foo/create_service.rb
ee/app/validators/ee/foo_attr_validator.rb
ee/app/workers/ee/foo_worker.rb

Testing EE features based on CE features

To test an EE namespaced module that extends a CE class with EE features, create the spec file as you usually would in the ee/spec directory, including the second ee/ subdirectory. For example, an extension ee/app/models/ee/user.rb would have its tests in ee/spec/models/ee/user_spec.rb.

In the RSpec.describe call, use the CE class name where the EE module would be used. For example, in ee/spec/models/ee/user_spec.rb, the test would start with:

RSpec.describe User do
  describe 'ee feature added through extension'
end

Overriding CE methods

To override a method present in the CE codebase, use prepend. It lets you override a method in a class with a method from a module, while still having access the class's implementation with super.

There are a few gotchas with it:

you should always extend ::Gitlab::Utils::Override and use override to guard the overrider method to ensure that if the method gets renamed in CE, the EE override isn't silently forgotten.
when the overrider would add a line in the middle of the CE implementation, you should refactor the CE method and split it in smaller methods. Or create a "hook" method that is empty in CE, and with the EE-specific implementation in EE.
when the original implementation contains a guard clause (for example, return unless condition), we cannot easily extend the behavior by overriding the method, because we can't know when the overridden method (that is, calling super in the overriding method) would want to stop early. In this case, we shouldn't just override it, but update the original method to make it call the other method we want to extend, like a template method pattern. For example, given this base:
```
  class Base
    def execute
      return unless enabled?

      # ...
      # ...
    end
  end
```
Instead of just overriding Base#execute, we should update it and extract the behavior into another method:
```
  class Base
    def execute
      return unless enabled?

      do_something
    end

    private

    def do_something
      # ...
      # ...
    end
  end
```
Then we're free to override that do_something without worrying about the guards:
```
  module EE::Base
    extend ::Gitlab::Utils::Override

    override :do_something
    def do_something
      # Follow the above pattern to call super and extend it
    end
  end
```

When prepending, place them in the ee/ specific sub-directory, and wrap class or module in module EE to avoid naming conflicts.

For example to override the CE implementation of ApplicationController#after_sign_out_path_for:

def after_sign_out_path_for(resource)
  current_application_settings.after_sign_out_path.presence || new_user_session_path
end

Instead of modifying the method in place, you should add prepend to the existing file:

JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end
```0

And create a new file in the `ee/` sub-directory with the altered
implementation:

```ruby
JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end
```1

##### Overriding CE class methods

The same applies to class methods, except we want to use
`ActiveSupport::Concern` and put `extend ::Gitlab::Utils::Override`
within the block of `class_methods`. Here's an example:

```ruby
JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end
```2

#### Use self-descriptive wrapper methods

When it's not possible/logical to modify the implementation of a method, then
wrap it in a self-descriptive method and use that method.

For example, in GitLab-FOSS, the only user created by the system is `Users::Internal.ghost`
but in EE there are several types of bot-users that aren't really users. It would
be incorrect to override the implementation of `User#ghost?`, so instead we add
a method `#internal?` to `app/models/user.rb`. The implementation:

```ruby
JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end
```3

In EE, the implementation `ee/app/models/ee/users.rb` would be:

```ruby
JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end
```4

### Code in `config/initializers`

Rails initialization code is located in

- `config/initializers` for CE-only features
- `ee/config/initializers` for EE features

Use `Gitlab.ee { ... }`/`Gitlab.ee?` in `config/initializers` only when
splitting is not possible. For example:

```ruby
JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end
```5

### Code in `config/routes`

When we add `draw :admin` in `config/routes.rb`, the application tries to
load the file located in `config/routes/admin.rb`, and also try to load the
file located in `ee/config/routes/admin.rb`.

In EE, it should at least load one file, at most two files. If it cannot find
any files, an error is raised. In CE, since we don't know if an
EE route exists, it doesn't raise any errors even if it cannot find anything.

This means if we want to extend a particular CE route file, just add the same
file located in `ee/config/routes`. If we want to add an EE only route, we
could still put `draw :ee_only` in both CE and EE, and add
`ee/config/routes/ee_only.rb` in EE, similar to `render_if_exists`.

### Code in `app/controllers/`

In controllers, the most common type of conflict is with `before_action` that
has a list of actions in CE but EE adds some actions to that list.

The same problem often occurs for `params.require` / `params.permit` calls.

**Mitigations**

Separate CE and EE actions/keywords. For instance for `params.require` in
`ProjectsController`:

```ruby
JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end
```6

In the `EE::ProjectsController` module:

```ruby
JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end
```7

### Code in `app/models/`

EE-specific models should be defined in `ee/app/models/`.

To override a CE model create the file in
`ee/app/models/ee/` and add new code to a `prepended` block.

ActiveRecord `enums` should be entirely
[defined in FOSS](database/creating_enums.md#all-of-the-keyvalue-pairs-should-be-defined-in-foss).

### Code in `app/views/`

It's a very frequent problem that EE is adding some specific view code in a CE
view. For instance the approval code in the project's settings page.

**Mitigations**

Blocks of code that are EE-specific should be moved to partials. This
avoids conflicts with big chunks of HAML code that are not fun to
resolve when you add the indentation to the equation.

EE-specific views should be placed in `ee/app/views/`, using extra
sub-directories if appropriate.

#### Using `render_if_exists`

Instead of using regular `render`, we should use `render_if_exists`, which
doesn't render anything if it cannot find the specific partial. We use this
so that we could put `render_if_exists` in CE, keeping code the same between
CE and EE.

The advantages of this:

- Very clear hints about where we're extending EE views while reading CE code.

The disadvantage of this:

- If we have typos in the partial name, it would be silently ignored.

##### Caveats

The `render_if_exists` view path argument must be relative to `app/views/` and `ee/app/views`.
Resolving an EE template path that is relative to the CE view path doesn't work.

```ruby
JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end
```8

#### Using `render_ce`

For `render` and `render_if_exists`, they search for the EE partial first,
and then CE partial. They would only render a particular partial, not all
partials with the same name. We could take the advantage of this, so that
the same partial path (for example, `projects/settings/archive`) could
be referring to the CE partial in CE (that is,
`app/views/projects/settings/_archive.html.haml`), while EE
partial in EE (that is,
`ee/app/views/projects/settings/_archive.html.haml`). This way,
we could show different things between CE and EE.

However sometimes we would also want to reuse the CE partial in EE partial
because we might just want to add something to the existing CE partial. We
could workaround this by adding another partial with a different name, but it
would be tedious to do so.

In this case, we could as well just use `render_ce` which would ignore any EE
partials. One example would be
`ee/app/views/projects/settings/_archive.html.haml`:

```ruby
JH_DISABLED_FEATURES = %i[some_domain_new_feature_name].freeze

override :feature_available?
def feature_available?(feature)
  super && JH_DISABLED_FEATURES.exclude?(feature)
end
```9

In the above example, we can't use
`render 'projects/settings/archive'` because it would find the
same EE partial, causing infinite recursion. Instead, we could use `render_ce`
so it ignores any partials in `ee/` and then it would render the CE partial
(that is, `app/views/projects/settings/_archive.html.haml`)
for the same path (that is, `projects/settings/archive`). This way
we could easily wrap around the CE partial.

### Code in `lib/gitlab/background_migration/`

When you create EE-only background migrations, you have to plan for users that
downgrade GitLab EE to CE. In other words, every EE-only migration has to be present in
CE code but with no implementation, instead you need to extend it on EE side.

GitLab CE:

```ruby
stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
```0

GitLab EE:

```ruby
stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
```1

### Code in `app/graphql/`

EE-specific mutations, resolvers, and types should be added to
`ee/app/graphql/{mutations,resolvers,types}`.

To override a CE mutation, resolver, or type, create the file in
`ee/app/graphql/ee/{mutations,resolvers,types}` and add new code to a
`prepended` block.

For example, if CE has a mutation called `Mutations::Tanukis::Create` and you
wanted to add a new argument, place the EE override in
`ee/app/graphql/ee/mutations/tanukis/create.rb`:

```ruby
stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
```2

### Code in `lib/`

Place EE-specific logic in the top-level `EE` module namespace. Namespace the
class beneath the `EE` module as you usually would.

For example, if CE has LDAP classes in `lib/gitlab/ldap/` then you would place
EE-specific LDAP classes in `ee/lib/ee/gitlab/ldap`.

### Code in `lib/api/`

It can be very tricky to extend EE features by a single line of `prepend_mod_with`,
and for each different [Grape](https://github.com/ruby-grape/grape) feature, we
might need different strategies to extend it. To apply different strategies
easily, we would use `extend ActiveSupport::Concern` in the EE module.

Put the EE module files following
[Extend CE features with EE backend code](#extend-ce-features-with-ee-backend-code).

#### EE API routes

For EE API routes, we put them in a `prepended` block:

```ruby
stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
```3

We need to use the full qualifier for some constants due to namespace differences.

#### EE parameters

We can define `params` and use `use` in another `params` definition to
include parameters defined in EE. However, we need to define the "interface" first
in CE in order for EE to override it. We don't have to do this in other places
due to `prepend_mod_with`, but Grape is complex internally and we couldn't easily
do that, so we follow regular object-oriented practices that we define the
interface first here.

For example, suppose we have a few more optional parameters for EE. We can move the
parameters out of the `Grape::API::Instance` class to a helper module, so we can inject it
before it would be used in the class.

```ruby
stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
```4

Given this CE API `params`:

```ruby
stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
```5

We could override it in EE module:

```ruby
stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
```6

#### EE helpers

To make it easy for an EE module to override the CE helpers, we need to define
those helpers we want to extend first. Try to do that immediately after the
class definition to make it easy and clear:

```ruby
stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
```7

And then we can follow regular object-oriented practices to override it:

```ruby
stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
```8

#### EE-specific behavior

Sometimes we need EE-specific behavior in some of the APIs. Usually we could
use EE methods to override CE methods, however API routes are not methods and
therefore cannot be overridden. We need to extract them into a standalone
method, or introduce some "hooks" where we could inject behavior in the CE
route. Something like this:

```ruby
stub_saas_features(purchases_additional_minutes: false)

::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
```9

`update_merge_request_ee` doesn't do anything in CE, but
then we could override it in EE:

```ruby
it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end
```0

#### EE `route_setting`

It's very hard to extend this in an EE module, and this is storing
some meta-data for a particular route. Given that, we could leave the
EE `route_setting` in CE as it doesn't hurt and we don't use
those meta-data in CE.

We could revisit this policy when we're using `route_setting` more and whether
or not we really need to extend it from EE. For now we're not using it much.

#### Utilizing class methods for setting up EE-specific data

Sometimes we need to use different arguments for a particular API route, and we
can't easily extend it with an EE module because Grape has different context in
different blocks. In order to overcome this, we need to move the data to a class
method that resides in a separate module or class. This allows us to extend that
module or class before its data is used, without having to place a
`prepend_mod_with` in the middle of CE code.

For example, in one place we need to pass an extra argument to
`at_least_one_of` so that the API could consider an EE-only argument as the
least argument. We would approach this as follows:

```ruby
it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end
```1

And then we could easily extend that argument in the EE class method:

```ruby
it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end
```2

It could be annoying if we need this for a lot of routes, but it might be the
simplest solution right now.

This approach can also be used when models define validations that depend on
class methods. For example:

```ruby
it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end
```3

Instead of taking this approach, we would refactor our code into the following:

```ruby
it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end
```4

### Code in `spec/`

When you're testing EE-only features, avoid adding examples to the
existing CE specs. Also do not change existing CE examples, since they
should remain working as-is when EE is running without a license.

Instead place EE specs in the `ee/spec` folder.

### Code in `spec/factories`

Use `FactoryBot.modify` to extend factories already defined in CE.

You cannot define new factories (even nested ones) inside the `FactoryBot.modify` block. You can do so in a
separate `FactoryBot.define` block as shown in the example below:

```ruby
it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end
```5

## Separation of EE code in the frontend

To separate EE-specific JS-files, move the files into an `ee` folder.

For example there can be an
`app/assets/javascripts/protected_branches/protected_branches_bundle.js` and an
EE counterpart
`ee/app/assets/javascripts/protected_branches/protected_branches_bundle.js`.
The corresponding import statement would then look like this:

```ruby
it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end
```6

### Add new EE-only features in the frontend

If the feature being developed is not present in CE, add your entry point in
`ee/`. For example:

```ruby
it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end
```7

Feature guarding `licensed_feature_available?` and `License.feature_available?` typical
occurs in the controller, as described in the [backend guide](#ee-only-features).

#### Testing EE-only frontend features

Add your EE tests to `ee/spec/frontend/` following the same directory structure you use for CE.

Check the note under [Testing EE-only backend features](#testing-ee-only-backend-features) regarding
enabling licensed features.

### Extend CE features with EE frontend code

Use the [`push_licensed_feature`](#guard-your-ee-feature) to guard frontend features that extend
existing views:

```ruby
it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end
```8

```ruby
it 'purchases/additional_minutes is not available' do
  # tests assuming purchases_additional_minutes is not enabled by default
  ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => false
end

context 'when purchases_additional_minutes is available' do
  before do
    stub_saas_features(purchases_additional_minutes: true)
  end

  it 'returns true' do
    ::Gitlab::Saas.feature_available?(:purchases_additional_minutes) # => true
  end
end
```9

```ruby
  stub_licensed_features(my_awesome_feature_name: true)
```0

Verify your feature appears in `gon.licensed_features` in the browser console.

#### Extend Vue applications with EE Vue components

EE licensed features that enhance existing functionality in the UI add new
elements or interactions to your Vue application as components.

You can import EE components inside CE components to add EE features.

Use an `ee_component` alias to import an EE component. In EE the `ee_component` import alias points
to the `ee/app/assets/javascripts` directory. While in CE this alias will be resolved to an empty
component that renders nothing.

Here is an example of an EE component imported to a CE component:

```ruby
  stub_licensed_features(my_awesome_feature_name: true)
```1

NOTE:
An EE component can be imported
[asynchronously](https://v2.vuejs.org/v2/guide/components-dynamic-async.html#Async-Components) if
its rendering within CE codebase relies on some check (e.g. a feature flag check).

Check `glFeatures` to ensure that the Vue components are guarded. The components render only when
the license is present.

```ruby
  stub_licensed_features(my_awesome_feature_name: true)
```2

NOTE:
Do not use mixins unless ABSOLUTELY NECESSARY. Try to find an alternative pattern.

##### Recommended alternative approach (named/scoped slots)

- We can use slots and/or scoped slots to achieve the same thing as we did with mixins. If you only need an EE component there is no need to create the CE component.

1. First, we have a CE component that can render a slot in case we need EE template and functionality to be decorated on top of the CE base.

```ruby
  stub_licensed_features(my_awesome_feature_name: true)
```3

1. Next, we render the EE component, and inside of the EE component we render the CE component and add additional content in the slot.

```ruby
  stub_licensed_features(my_awesome_feature_name: true)
```4

1. Finally, wherever the component is needed we can require it like so

`import MyComponent from 'ee_else_ce/path/my_component'.vue`

- this way the correct component is included for either the CE or EE implementation

**For EE components that need different results for the same computed values, we can pass in props to the CE wrapper as seen in the example.**

- **EE extra HTML**
  - For the templates that have extra HTML in EE we should move it into a new component and use the `ee_else_ce` import alias

#### Extend other JS code

To extend JS files, complete the following steps:

1. Use the `ee_else_ce` helper, where that EE only code must be inside the `ee/` folder.
   1. Create an EE file with only the EE, and extend the CE counterpart.
   1. For code inside functions that can't be extended, move the code to a new file and use `ee_else_ce` helper:

```ruby
  stub_licensed_features(my_awesome_feature_name: true)
```5

In some cases, you'll need to extend other logic in your application. To extend your JS
modules, create an EE version of the file and extend it with your custom logic:

```ruby
  stub_licensed_features(my_awesome_feature_name: true)
```6

```ruby
  stub_licensed_features(my_awesome_feature_name: true)
```7

#### Testing modules using EE/CE aliases

When writing Frontend tests, if the module under test imports other modules with `ee_else_ce/...` and these modules are also needed by the relevant test, then the relevant test **must** import these modules with `ee_else_ce/...`. This avoids unexpected EE or FOSS failures, and helps ensure the EE behaves like CE when it is unlicensed.

For example:

```ruby
  stub_licensed_features(my_awesome_feature_name: true)
```8

```ruby
  stub_licensed_features(my_awesome_feature_name: true)
```9

### Running EE vs CE tests

Whenever you create tests for both CE and EE environments, you need to take some steps to ensure that both tests pass locally and on the pipeline when run.

- By default, tests run in the EE environment, executing both EE and CE tests.
- If you want to test only the CE file in the FOSS environment, you need to run the following command:

```ruby
class User < ActiveRecord::Base
  # ... lots of code here ...
end

User.prepend_mod
```0

As for CE tests we only add CE features, it may fail in the EE environment if EE-specific mock data is missing. To ensure CE tests work in both environments:

- Use the `ee_else_ce_jest` alias when importing mock data. For example:

```ruby
class User < ActiveRecord::Base
  # ... lots of code here ...
end

User.prepend_mod
```1

- Make sure that you have a CE and an EE `mock_data` file with an object (in the example above, `sidebarDataCountResponse`) with the corresponding data. One with only CE features data for the CE file and another with both CE and EE features data.

- In the CE file `expect` blocks, if you need to compare an object, use `toMatchObject` instead of `toEqual`, so it doesn't expect that EE data to exist in the CE data. For example:

```ruby
class User < ActiveRecord::Base
  # ... lots of code here ...
end

User.prepend_mod
```2

#### SCSS code in `assets/stylesheets`

If a component you're adding styles for is limited to EE, it is better to have a
separate SCSS file in an appropriate directory within `app/assets/stylesheets`.

In some cases, this is not entirely possible or creating dedicated SCSS file is an overkill,
for example, a text style of some component is different for EE. In such cases,
styles are usually kept in a stylesheet that is common for both CE and EE, and it is wise
to isolate such ruleset from rest of CE rules (along with adding comment describing the same)
to avoid conflicts during CE to EE merge.

```ruby
class User < ActiveRecord::Base
  # ... lots of code here ...
end

User.prepend_mod
```3

```ruby
class User < ActiveRecord::Base
  # ... lots of code here ...
end

User.prepend_mod
```4

### GitLab-svgs

Conflicts in `app/assets/images/icons.json` or `app/assets/images/icons.svg` can
be resolved by regenerating those assets with
[`yarn run svg`](https://gitlab.com/gitlab-org/gitlab-svgs).