Merge branch '325800-doc-jh-features' into 'master'

Add `prepend_mod` and a new JH merge requests review guidance

See merge request gitlab-org/gitlab!57807

app/helpers/appearances_helper.rb

@@ -83,5 +83,4 @@ module AppearancesHelper
   end
 end
 
-AppearancesHelper.prepend_if_ee('EE::AppearancesHelper')
-AppearancesHelper.prepend_if_jh('JH::AppearancesHelper')
+AppearancesHelper.prepend_mod

app/helpers/application_helper.rb

@@ -409,5 +409,4 @@ module ApplicationHelper
   end
 end
 
-ApplicationHelper.prepend_if_ee('EE::ApplicationHelper')
-ApplicationHelper.prepend_if_jh('JH::ApplicationHelper')
+ApplicationHelper.prepend_mod

config/initializers/0_inject_enterprise_edition_module.rb

@@ -3,42 +3,50 @@
 require 'active_support/inflector'
 
 module InjectEnterpriseEditionModule
-  def prepend_if_ee(constant, with_descendants: false)
-    return unless Gitlab.ee?
-
-    prepend_module(constant.constantize, with_descendants)
+  def prepend_if_ee(constant_with_prefix, namespace: Object, with_descendants: false)
+    prepend_mod_for(
+      constant_without_prefix(constant_with_prefix),
+      namespace: namespace,
+      with_descendants: with_descendants)
   end
 
-  def extend_if_ee(constant)
-    extend(constant.constantize) if Gitlab.ee?
+  def extend_if_ee(constant_with_prefix, namespace: Object)
+    each_extension_for(
+      constant_without_prefix(constant_with_prefix),
+      namespace,
+      &method(:extend))
   end
 
-  def include_if_ee(constant)
-    include(constant.constantize) if Gitlab.ee?
+  def include_if_ee(constant_with_prefix, namespace: Object)
+    each_extension_for(
+      constant_without_prefix(constant_with_prefix),
+      namespace,
+      &method(:include))
   end
 
-  def prepend_ee_mod(with_descendants: false)
-    return unless Gitlab.ee?
-
-    prepend_module(ee_module, with_descendants)
+  def prepend_mod(with_descendants: false)
+    prepend_mod_for(name, with_descendants: with_descendants)
   end
+  alias_method :prepend_ee_mod, :prepend_mod
 
-  def extend_ee_mod
-    extend(ee_module) if Gitlab.ee?
+  def extend_mod
+    each_extension_for(name, Object, &method(:extend))
   end
+  alias_method :extend_ee_mod, :extend_mod
 
-  def include_ee_mod
-    include(ee_module) if Gitlab.ee?
+  def include_mod
+    each_extension_for(name, Object, &method(:include))
   end
+  alias_method :include_ee_mod, :include_mod
 
-  def prepend_if_jh(constant, with_descendants: false)
-    return unless Gitlab.jh?
+  private
 
-    prepend_module(constant.constantize, with_descendants)
+  def prepend_mod_for(constant_name, namespace: Object, with_descendants: false)
+    each_extension_for(constant_name, namespace) do |constant|
+      prepend_module(constant, with_descendants)
+    end
   end
 
-  private
-
   def prepend_module(mod, with_descendants)
     prepend(mod)
 
@@ -47,8 +55,34 @@ module InjectEnterpriseEditionModule
     end
   end
 
-  def ee_module
-    ::EE.const_get(name, false)
+  def each_extension_for(constant_name, namespace)
+    Gitlab.extensions.each do |extension_name|
+      extension_namespace =
+        const_get_maybe_false(namespace, extension_name.upcase)
+
+      extension_module =
+        const_get_maybe_false(extension_namespace, constant_name)
+
+      yield(extension_module) if extension_module
+    end
+  end
+
+  def const_get_maybe_false(mod, name)
+    # We're still heavily relying on Rails autoloading instead of zeitwerk,
+    # therefore this check: `mod.const_defined?(name, false)`
+    # Is not reliable, which may return false while it's defined.
+    # After we moved everything over to zeitwerk we can avoid rescuing
+    # NameError and just check if const_defined?
+    # mod && mod.const_defined?(name, false) && mod.const_get(name, false)
+    mod && mod.const_get(name, false)
+  rescue NameError
+    false
+  end
+
+  def constant_without_prefix(constant_with_prefix)
+    constant_with_prefix
+      .delete_prefix('::') # TODO: Some calling sites are passing this prefix
+      .delete_prefix('EE::')
   end
 end
 

doc/development/jh_features_review.md

+---
+stage: none
+group: unassigned
+info: https://gitlab.com/gitlab-jh/gitlab
+---
+
+# Guidelines for reviewing JiHu (JH) Edition related merge requests
+
+We have two kinds of changes related to JH:
+
+- Inside `jh/`
+  - This is beyond EE repository and not the intention for this documentation.
+- Outside `jh/`
+  - These will have to sit in EE repository, so reviewers and maintainers for
+    EE repository will have to review and maintain. This includes codes like
+    `Gitlab.jh?`, and how it attempts to load codes under `jh/` just like we
+    have codes which will load codes under `ee/`.
+  - This documentation intended to guide how those codes should look like, so
+    we'll have better understanding what are the changes needed for looking up
+    codes under `jh/`.
+  - We will generalize this so both EE and JH can share the same mechanism,
+    then we wouldn't have to treat them differently.
+
+If needed, review the corresponding JH merge request located at [JH repository](https://gitlab.com/gitlab-jh/gitlab)
+
+## Act as EE when `jh/` does not exist
+
+- In the case of EE repository, `jh/` does not exist so it should just act like EE (or CE when the license is absent)
+- In the case of JH repository, `jh/` does exist but `EE_ONLY` environment variable can be set to force it run under EE mode.
+- In the case of JH repository, `jh/` does exist but `FOSS_ONLY` environment variable can be set to force it run under CE mode.
+
+## CI pipelines in a JH context
+
+EE repository does not have `jh/` directory therefore there is no way to run
+JH pipelines in the EE repository. All JH tests should go to [JH repository](https://gitlab.com/gitlab-jh/gitlab).
+
+The top-level JH CI configuration is located at `jh/.gitlab-ci.yml` (which
+does not exist in EE repository) and it'll include EE CI configurations
+accordingly. Sometimes it's needed to update the EE CI configurations for JH
+to customize more easily.
+
+### JH features based on CE or EE features
+
+For features that build on existing CE/EE features, a module in the `JH`
+namespace injected in the CE/EE class/module is needed. This aligns with
+what we're doing with EE features.
+
+See [EE features based on CE features](ee_features.md#ee-features-based-on-ce-features) for more details.
+
+For example, to prepend a module into the `User` class you would use
+the following approach:
+
+```ruby
+class User < ActiveRecord::Base
+  # ... lots of code here ...
+end
+
+User.prepend_mod
+```
+
+Under EE, `User.prepend_mod` will attempt to:
+
+- Load EE module
+
+Under JH, `User.prepend_mod` will attempt to:
+
+- Load EE module, and:
+- Load JH module
+
+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 and JH modules by the name of the receiver module.
+
+If reviewing the corresponding JH file is needed, it should be found at
+[JH repository](https://gitlab.com/gitlab-jh/gitlab).
+
+### General guidance for writing JH extensions
+
+See [Guidelines for implementing Enterprise Edition features](ee_features.md)
+for general guidance.

ee/lib/gitlab/import_export/group_helper.rb

-# frozen_string_literal: true
-
-module Gitlab
-  module ImportExport
-    module GroupHelper
-      def group_wiki_repo_bundle_filename(group_id)
-        "#{group_id}.wiki.bundle"
-      end
-
-      def group_wiki_repo_bundle_path(shared, filename)
-        File.join(shared.export_path, 'repositories', filename)
-      end
-
-      def group_wiki_repo_bundle_full_path(shared, group_id)
-        group_wiki_repo_bundle_path(shared, group_wiki_repo_bundle_filename(group_id))
-      end
-    end
-  end
-end

lib/gitlab.rb

@@ -92,6 +92,16 @@ module Gitlab
     Rails.env.development? || Rails.env.test?
   end
 
+  def self.extensions
+    if jh?
+      %w[ee jh]
+    elsif ee?
+      %w[ee]
+    else
+      %w[]
+    end
+  end
+
   def self.ee?
     @is_ee ||=
       # We use this method when the Rails environment is not loaded. This

lib/gitlab/import_export.rb

@@ -99,11 +99,19 @@ module Gitlab
     def group_config_file
       Rails.root.join('lib/gitlab/import_export/group/import_export.yml')
     end
+
+    def group_wiki_repo_bundle_filename(group_id)
+      "#{group_id}.wiki.bundle"
+    end
+
+    def group_wiki_repo_bundle_path(shared, filename)
+      File.join(shared.export_path, 'repositories', filename)
+    end
+
+    def group_wiki_repo_bundle_full_path(shared, group_id)
+      group_wiki_repo_bundle_path(shared, group_wiki_repo_bundle_filename(group_id))
+    end
   end
 end
 
-Gitlab::ImportExport.prepend_if_ee('EE::Gitlab::ImportExport')
-
-# The methods in `Gitlab::ImportExport::GroupHelper` should be available as both
-# instance and class methods.
-Gitlab::ImportExport.extend_if_ee('Gitlab::ImportExport::GroupHelper')
+Gitlab::ImportExport.prepend_mod

lib/gitlab/subscription_portal.rb

@@ -12,5 +12,5 @@ module Gitlab
   end
 end
 
-Gitlab::SubscriptionPortal.prepend_if_jh('JH::Gitlab::SubscriptionPortal')
+Gitlab::SubscriptionPortal.prepend_mod
 Gitlab::SubscriptionPortal::SUBSCRIPTIONS_URL = Gitlab::SubscriptionPortal.subscriptions_url.freeze

qa/qa/page/admin/menu.rb

@@ -107,4 +107,4 @@ module QA
   end
 end
 
-QA::Page::Admin::Menu.prepend_if_ee('QA::EE::Page::Admin::Menu')
+QA::Page::Admin::Menu.prepend_if_ee('Page::Admin::Menu', namespace: QA)

qa/qa/page/admin/overview/groups/edit.rb

@@ -20,4 +20,4 @@ module QA
   end
 end
 
-QA::Page::Admin::Overview::Groups::Edit.prepend_if_ee('QA::EE::Page::Admin::Overview::Groups::Edit')
+QA::Page::Admin::Overview::Groups::Edit.prepend_if_ee('Page::Admin::Overview::Groups::Edit', namespace: QA)

qa/qa/page/component/issue_board/show.rb

@@ -137,4 +137,4 @@ module QA
   end
 end
 
-QA::Page::Component::IssueBoard::Show.prepend_if_ee('QA::EE::Page::Component::IssueBoard::Show')
+QA::Page::Component::IssueBoard::Show.prepend_if_ee('Page::Component::IssueBoard::Show', namespace: QA)

qa/qa/page/dashboard/projects.rb

@@ -45,4 +45,4 @@ module QA
   end
 end
 
-QA::Page::Dashboard::Projects.prepend_if_ee('QA::EE::Page::Dashboard::Projects')
+QA::Page::Dashboard::Projects.prepend_if_ee('Page::Dashboard::Projects', namespace: QA)

qa/qa/page/file/show.rb

@@ -62,4 +62,4 @@ module QA
   end
 end
 
-QA::Page::File::Show.prepend_if_ee('QA::EE::Page::File::Show')
+QA::Page::File::Show.prepend_if_ee('Page::File::Show', namespace: QA)

qa/qa/page/group/menu.rb

@@ -83,4 +83,4 @@ module QA
   end
 end
 
-QA::Page::Group::Menu.prepend_if_ee('QA::EE::Page::Group::Menu')
+QA::Page::Group::Menu.prepend_if_ee('Page::Group::Menu', namespace: QA)

qa/qa/page/group/settings/general.rb

@@ -129,4 +129,4 @@ module QA
   end
 end
 
-QA::Page::Group::Settings::General.prepend_if_ee('QA::EE::Page::Group::Settings::General')
+QA::Page::Group::Settings::General.prepend_if_ee('Page::Group::Settings::General', namespace: QA)

qa/qa/page/main/menu.rb

@@ -175,4 +175,4 @@ module QA
   end
 end
 
-QA::Page::Main::Menu.prepend_if_ee('QA::EE::Page::Main::Menu')
+QA::Page::Main::Menu.prepend_if_ee('Page::Main::Menu', namespace: QA)

qa/qa/page/merge_request/new.rb

@@ -41,4 +41,4 @@ module QA
   end
 end
 
-QA::Page::MergeRequest::New.prepend_if_ee('QA::EE::Page::MergeRequest::New')
+QA::Page::MergeRequest::New.prepend_if_ee('Page::MergeRequest::New', namespace: QA)

qa/qa/page/merge_request/show.rb

@@ -390,4 +390,4 @@ module QA
   end
 end
 
-QA::Page::MergeRequest::Show.prepend_if_ee('QA::EE::Page::MergeRequest::Show')
+QA::Page::MergeRequest::Show.prepend_if_ee('Page::MergeRequest::Show', namespace: QA)

qa/qa/page/milestone/show.rb

@@ -30,4 +30,4 @@ module QA
   end
 end
 
-QA::Page::Milestone::Show.prepend_if_ee('QA::EE::Page::Milestone::Show')
+QA::Page::Milestone::Show.prepend_if_ee('Page::Milestone::Show', namespace: QA)

qa/qa/page/profile/menu.rb

@@ -56,4 +56,4 @@ module QA
   end
 end
 
-QA::Page::Profile::Menu.prepend_if_ee('QA::EE::Page::Profile::Menu')
+QA::Page::Profile::Menu.prepend_if_ee('Page::Profile::Menu', namespace: QA)

qa/qa/page/project/issue/index.rb

@@ -85,4 +85,4 @@ module QA
   end
 end
 
-QA::Page::Project::Issue::Index.prepend_if_ee('QA::EE::Page::Project::Issue::Index')
+QA::Page::Project::Issue::Index.prepend_if_ee('Page::Project::Issue::Index', namespace: QA)

qa/qa/page/project/issue/show.rb

@@ -70,4 +70,4 @@ module QA
   end
 end
 
-QA::Page::Project::Issue::Show.prepend_if_ee('QA::EE::Page::Project::Issue::Show')
+QA::Page::Project::Issue::Show.prepend_if_ee('Page::Project::Issue::Show', namespace: QA)

qa/qa/page/project/job/show.rb

@@ -75,4 +75,4 @@ module QA
   end
 end
 
-QA::Page::Project::Job::Show.prepend_if_ee('QA::EE::Page::Project::Job::Show')
+QA::Page::Project::Job::Show.prepend_if_ee('Page::Project::Job::Show', namespace: QA)

qa/qa/page/project/menu.rb

@@ -56,4 +56,4 @@ module QA
   end
 end
 
-QA::Page::Project::Menu.prepend_if_ee('QA::EE::Page::Project::Menu')
+QA::Page::Project::Menu.prepend_if_ee('Page::Project::Menu', namespace: QA)

qa/qa/page/project/new.rb

@@ -72,4 +72,4 @@ module QA
   end
 end
 
-QA::Page::Project::New.prepend_if_ee('QA::EE::Page::Project::New')
+QA::Page::Project::New.prepend_if_ee('Page::Project::New', namespace: QA)

qa/qa/page/project/operations/metrics/show.rb

@@ -134,4 +134,4 @@ module QA
   end
 end
 
-QA::Page::Project::Operations::Metrics::Show.prepend_if_ee('QA::EE::Page::Project::Operations::Metrics::Show')
+QA::Page::Project::Operations::Metrics::Show.prepend_if_ee('Page::Project::Operations::Metrics::Show', namespace: QA)

qa/qa/page/project/packages/index.rb

@@ -27,4 +27,4 @@ module QA
   end
 end
 
-QA::Page::Project::Packages::Index.prepend_if_ee('QA::EE::Page::Project::Packages::Index')
+QA::Page::Project::Packages::Index.prepend_if_ee('Page::Project::Packages::Index', namespace: QA)

qa/qa/page/project/pipeline/index.rb

@@ -67,4 +67,4 @@ module QA
   end
 end
 
-QA::Page::Project::Pipeline::Index.prepend_if_ee('QA::EE::Page::Project::Pipeline::Index')
+QA::Page::Project::Pipeline::Index.prepend_if_ee('Page::Project::Pipeline::Index', namespace: QA)

qa/qa/page/project/pipeline/show.rb

@@ -117,4 +117,4 @@ module QA
   end
 end
 
-QA::Page::Project::Pipeline::Show.prepend_if_ee('QA::EE::Page::Project::Pipeline::Show')
+QA::Page::Project::Pipeline::Show.prepend_if_ee('Page::Project::Pipeline::Show', namespace: QA)

qa/qa/page/project/settings/ci_cd.rb

@@ -43,4 +43,4 @@ module QA
   end
 end
 
-QA::Page::Project::Settings::CICD.prepend_if_ee("QA::EE::Page::Project::Settings::CICD")
+QA::Page::Project::Settings::CICD.prepend_if_ee("Page::Project::Settings::CICD", namespace: QA)

qa/qa/page/project/settings/integrations.rb

@@ -23,4 +23,4 @@ module QA
   end
 end
 
-QA::Page::Project::Settings::Integrations.prepend_if_ee('QA::EE::Page::Project::Settings::Integrations')
+QA::Page::Project::Settings::Integrations.prepend_if_ee('Page::Project::Settings::Integrations', namespace: QA)

qa/qa/page/project/settings/main.rb

@@ -57,4 +57,4 @@ module QA
   end
 end
 
-QA::Page::Project::Settings::Main.prepend_if_ee("QA::EE::Page::Project::Settings::Main")
+QA::Page::Project::Settings::Main.prepend_if_ee("Page::Project::Settings::Main", namespace: QA)

qa/qa/page/project/settings/merge_request.rb

@@ -38,4 +38,4 @@ module QA
   end
 end
 
-QA::Page::Project::Settings::MergeRequest.prepend_if_ee("QA::EE::Page::Project::Settings::MergeRequest")
+QA::Page::Project::Settings::MergeRequest.prepend_if_ee("Page::Project::Settings::MergeRequest", namespace: QA)

qa/qa/page/project/settings/mirroring_repositories.rb

@@ -129,4 +129,4 @@ module QA
   end
 end
 
-QA::Page::Project::Settings::MirroringRepositories.prepend_if_ee('QA::EE::Page::Project::Settings::MirroringRepositories')
+QA::Page::Project::Settings::MirroringRepositories.prepend_if_ee('Page::Project::Settings::MirroringRepositories', namespace: QA)

qa/qa/page/project/settings/protected_branches.rb

@@ -69,4 +69,4 @@ module QA
   end
 end
 
-QA::Page::Project::Settings::ProtectedBranches.prepend_if_ee('QA::EE::Page::Project::Settings::ProtectedBranches')
+QA::Page::Project::Settings::ProtectedBranches.prepend_if_ee('Page::Project::Settings::ProtectedBranches', namespace: QA)

qa/qa/page/project/settings/protected_tags.rb

@@ -43,4 +43,4 @@ module QA
   end
 end
 
-QA::Page::Project::Settings::ProtectedTags.prepend_if_ee('QA::EE::Page::Project::Settings::ProtectedTags')
+QA::Page::Project::Settings::ProtectedTags.prepend_if_ee('Page::Project::Settings::ProtectedTags', namespace: QA)

qa/qa/page/project/settings/repository.rb

@@ -62,4 +62,4 @@ module QA
   end
 end
 
-QA::Page::Project::Settings::Repository.prepend_if_ee('QA::EE::Page::Project::Settings::Repository')
+QA::Page::Project::Settings::Repository.prepend_if_ee('Page::Project::Settings::Repository', namespace: QA)

qa/qa/page/project/show.rb

@@ -180,4 +180,4 @@ module QA
   end
 end
 
-QA::Page::Project::Show.prepend_if_ee('QA::EE::Page::Project::Show')
+QA::Page::Project::Show.prepend_if_ee('Page::Project::Show', namespace: QA)

qa/qa/page/project/snippet/index.rb

@@ -26,4 +26,4 @@ module QA
   end
 end
 
-QA::Page::Project::Snippet::Index.prepend_if_ee('QA::EE::Page::Project::Snippet::Index')
+QA::Page::Project::Snippet::Index.prepend_if_ee('Page::Project::Snippet::Index', namespace: QA)

qa/qa/page/project/web_ide/edit.rb

@@ -311,4 +311,4 @@ module QA
   end
 end
 
-QA::Page::Project::WebIDE::Edit.prepend_if_ee('QA::EE::Page::Component::WebIDE::WebTerminalPanel')
+QA::Page::Project::WebIDE::Edit.prepend_if_ee('Page::Component::WebIDE::WebTerminalPanel', namespace: QA)

qa/qa/page/project/wiki/show.rb

@@ -14,4 +14,4 @@ module QA
   end
 end
 
-QA::Page::Project::Wiki::Show.prepend_if_ee('QA::EE::Page::Project::Wiki::Show')
+QA::Page::Project::Wiki::Show.prepend_if_ee('Page::Project::Wiki::Show', namespace: QA)

qa/qa/page/registration/welcome.rb

@@ -21,4 +21,4 @@ module QA
   end
 end
 
-QA::Page::Registration::Welcome.prepend_if_ee('QA::EE::Page::Registration::Welcome')
+QA::Page::Registration::Welcome.prepend_if_ee('Page::Registration::Welcome', namespace: QA)

qa/qa/runtime/env.rb

@@ -403,4 +403,4 @@ module QA
   end
 end
 
-QA::Runtime::Env.extend_if_ee('QA::EE::Runtime::Env')
+QA::Runtime::Env.extend_if_ee('Runtime::Env', namespace: QA)

qa/qa/scenario/test/sanity/selectors.rb

@@ -58,4 +58,4 @@ module QA
   end
 end
 
-QA::Scenario::Test::Sanity::Selectors.prepend_if_ee('QA::EE::Scenario::Test::Sanity::Selectors')
+QA::Scenario::Test::Sanity::Selectors.prepend_if_ee('Scenario::Test::Sanity::Selectors', namespace: QA)

spec/config/inject_enterprise_edition_module_spec.rb

+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+
+RSpec.describe InjectEnterpriseEditionModule do
+  let(:extension_name) { 'FF' }
+  let(:extension_namespace) { Module.new }
+  let(:fish_name) { 'Fish' }
+  let(:fish_class) { Class.new }
+  let(:fish_extension) { Module.new }
+
+  before do
+    # Make sure we're not relying on which mode we're running under
+    allow(Gitlab).to receive(:extensions).and_return([extension_name.downcase])
+
+    # Test on an imagined extension and imagined class
+    stub_const(fish_name, fish_class) # Fish
+    allow(fish_class).to receive(:name).and_return(fish_name)
+  end
+
+  shared_examples 'expand the extension with' do |method|
+    context 'when extension namespace is set at top-level' do
+      before do
+        stub_const(extension_name, extension_namespace) # FF
+        extension_namespace.const_set(fish_name, fish_extension) # FF::Fish
+      end
+
+      it "calls #{method} with the extension module" do
+        expect(fish_class).to receive(method).with(fish_extension)
+
+        fish_class.__send__("#{method}_if_ee", fish_name)
+      end
+
+      it "ignores EE prefix and calls #{method} with the extension module" do
+        expect(fish_class).to receive(method).with(fish_extension)
+
+        fish_class.__send__("#{method}_if_ee", "EE::#{fish_name}")
+      end
+
+      it "ignores ::EE prefix and calls #{method} with the extension module" do
+        expect(fish_class).to receive(method).with(fish_extension)
+
+        fish_class.__send__("#{method}_if_ee", "::EE::#{fish_name}")
+      end
+    end
+
+    context 'when extension namespace is set at another namespace' do
+      let(:another_namespace) { Module.new } # QA
+
+      before do
+        another_namespace.const_set(extension_name, extension_namespace) # QA::FF
+        extension_namespace.const_set(fish_name, fish_extension) # QA::FF::Fish
+      end
+
+      it "calls #{method} with the extension module from the additional namespace" do
+        expect(fish_class).to receive(method).with(fish_extension)
+
+        fish_class.__send__("#{method}_if_ee", fish_name, namespace: another_namespace)
+      end
+    end
+
+    context 'when extension namespace exists but not the extension' do
+      before do
+        stub_const(extension_name, extension_namespace) # FF
+      end
+
+      it "does not call #{method}" do
+        expect(fish_class).not_to receive(method).with(fish_extension)
+
+        fish_class.__send__("#{method}_if_ee", fish_name)
+      end
+    end
+
+    context 'when extension namespace does not exist' do
+      it "does not call #{method}" do
+        expect(fish_class).not_to receive(method).with(fish_extension)
+
+        fish_class.__send__("#{method}_if_ee", fish_name)
+      end
+    end
+  end
+
+  shared_examples 'expand the assumed extension with' do |method|
+    context 'when extension namespace is set at top-level' do
+      before do
+        stub_const(extension_name, extension_namespace) # FF
+        extension_namespace.const_set(fish_name, fish_extension) # FF::Fish
+      end
+
+      it "calls #{method} with the extension module" do
+        expect(fish_class).to receive(method).with(fish_extension)
+
+        fish_class.__send__("#{method}_mod")
+      end
+    end
+
+    context 'when extension namespace exists but not the extension' do
+      before do
+        stub_const(extension_name, extension_namespace) # FF
+      end
+
+      it "does not call #{method}" do
+        expect(fish_class).not_to receive(method).with(fish_extension)
+
+        fish_class.__send__("#{method}_mod")
+      end
+    end
+
+    context 'when extension namespace does not exist' do
+      it "does not call #{method}" do
+        expect(fish_class).not_to receive(method).with(fish_extension)
+
+        fish_class.__send__("#{method}_mod")
+      end
+    end
+  end
+
+  describe '#prepend_if_ee' do
+    it_behaves_like 'expand the extension with', :prepend
+  end
+
+  describe '#extend_if_ee' do
+    it_behaves_like 'expand the extension with', :extend
+  end
+
+  describe '#include_if_ee' do
+    it_behaves_like 'expand the extension with', :include
+  end
+
+  describe '#prepend_mod' do
+    it_behaves_like 'expand the assumed extension with', :prepend
+  end
+
+  describe '#extend_mod' do
+    it_behaves_like 'expand the assumed extension with', :extend
+  end
+
+  describe '#include_mod' do
+    it_behaves_like 'expand the assumed extension with', :include
+  end
+end