Add default branch name e2e test

Adds an e2e test of instance-wide default branch name setting
- Includes a test of creating a project from an existing repo

Update ApplicationSettings
- Makes it a class since it's not intended to be included (and this
avoids rubocop complaints about a module with instance variables)
- Allow settings to be restored
- Dedupe API client code

qa/qa/git/repository.rb

@@ -118,6 +118,10 @@ module QA
         run(%Q{git config user.signingkey #{@gpg_key_id} && git config gpg.program $(command -v gpg) && git commit -S -m "#{message}"}).to_s
       end
 
+      def current_branch
+        run("git rev-parse --abbrev-ref HEAD").to_s
+      end
+
       def push_changes(branch = 'master')
         run("git push #{uri} #{branch}", max_attempts: 3).to_s
       end

qa/qa/resource/project.rb

@@ -13,6 +13,7 @@ module QA
       attr_writer :initialize_with_readme
       attr_writer :auto_devops_enabled
 
+      attribute :default_branch
       attribute :id
       attribute :name
       attribute :add_name_uuid

qa/qa/runtime/application_settings.rb

@@ -2,9 +2,9 @@
 
 module QA
   module Runtime
-    module ApplicationSettings
-      extend self
-      extend Support::Api
+    class ApplicationSettings
+      class << self
+        include Support::Api
 
         APPLICATION_SETTINGS_PATH = '/application/settings'
 
@@ -14,6 +14,8 @@ module QA
         #   #set(allow_local_requests_from_web_hooks_and_services: true)
         # https://docs.gitlab.com/ee/api/settings.html
         def set_application_settings(**application_settings)
+          @original_application_settings = get_application_settings
+
           QA::Runtime::Logger.info("Setting application settings: #{application_settings}")
           r = put(Runtime::API::Request.new(api_client, APPLICATION_SETTINGS_PATH).url, **application_settings)
           raise "Couldn't set application settings #{application_settings.inspect}" unless r.code == QA::Support::Api::HTTP_STATUS_OK
@@ -23,22 +25,16 @@ module QA
           parse_body(get(Runtime::API::Request.new(api_client, APPLICATION_SETTINGS_PATH).url))
         end
 
-      private
-
-      def api_client
-        @api_client ||= begin
-          return Runtime::API::Client.new(:gitlab, personal_access_token: Runtime::Env.admin_personal_access_token) if Runtime::Env.admin_personal_access_token
-
-          user = Resource::User.fabricate_via_api! do |user|
-            user.username = Runtime::User.admin_username
-            user.password = Runtime::User.admin_password
+        def restore_application_settings(*application_settings_keys)
+          set_application_settings(@original_application_settings.slice(*application_settings_keys))
         end
 
-          unless user.admin?
-            raise "Administrator access is required to set application settings. User '#{user.username}' is not an administrator."
-          end
+        private
 
-          Runtime::API::Client.new(:gitlab, user: user)
+        def api_client
+          @api_client ||= Runtime::API::Client.as_admin
+        rescue AuthorizationError => e
+          raise "Administrator access is required to set application settings. #{e.message}"
         end
       end
     end

qa/qa/specs/features/api/3_create/repository/default_branch_name_setting_spec.rb

+# frozen_string_literal: true
+
+require 'securerandom'
+
+module QA
+  RSpec.describe 'Create' do
+    describe 'Default branch name instance setting', :requires_admin, :skip_live_env do
+      before(:context) do
+        Runtime::ApplicationSettings.set_application_settings(default_branch_name: 'main')
+      end
+
+      after(:context) do
+        Runtime::ApplicationSettings.restore_application_settings(:default_branch_name)
+      end
+
+      it 'sets the default branch name for a new project' do
+        project = Resource::Project.fabricate_via_api! do |project|
+          project.name = "default-branch-name"
+          project.initialize_with_readme = true
+        end
+
+        # It takes a moment to create the project. We wait until we
+        # know it exists before we try to clone it
+        Support::Waiter.wait_until { project.has_file?('README.md') }
+
+        Git::Repository.perform do |repository|
+          repository.uri = project.repository_http_location.uri
+          repository.use_default_credentials
+          repository.clone
+
+          expect(repository.current_branch).to eq('main')
+        end
+      end
+
+      it 'allows a project to be created via the CLI with a different default branch name' do
+        project_name = "default-branch-name-via-cli-#{SecureRandom.hex(8)}"
+        group = Resource::Group.fabricate_via_api!
+
+        Git::Repository.perform do |repository|
+          repository.init_repository
+          repository.uri = "#{Runtime::Scenario.gitlab_address}/#{group.full_path}/#{project_name}"
+          repository.use_default_credentials
+          repository.configure_identity('GitLab QA', 'root@gitlab.com')
+          repository.checkout('trunk', new_branch: true)
+          repository.commit_file('README.md', 'Created via the CLI', 'initial commit via CLI')
+          repository.push_changes('trunk')
+        end
+
+        project = Resource::Project.fabricate_via_api! do |project|
+          project.add_name_uuid = false
+          project.name = project_name
+          project.group = group
+        end
+
+        expect(project.default_branch).to eq('trunk')
+        expect(project).to have_file('README.md')
+        expect(project.commits.map { |commit| commit[:message].chomp })
+          .to include('initial commit via CLI')
+      end
+    end
+  end
+end

qa/spec/runtime/application_settings_spec.rb

@@ -16,12 +16,14 @@ describe QA::Runtime::ApplicationSettings do
         .with(api_client, '/application/settings')
         .and_return(request)
 
+      expect(described_class).to receive(:get_application_settings)
+
       expect(described_class)
         .to receive(:put)
         .with(request.url, { allow_local_requests_from_web_hooks_and_services: true })
         .and_return(Struct.new(:code).new(200))
 
-      subject.set_application_settings(allow_local_requests_from_web_hooks_and_services: true)
+      described_class.set_application_settings(allow_local_requests_from_web_hooks_and_services: true)
     end
   end
 
@@ -37,7 +39,7 @@ describe QA::Runtime::ApplicationSettings do
         .with(request.url)
         .and_return(get_response)
 
-      subject.get_application_settings
+      described_class.get_application_settings
     end
   end
 end