Extract AssignRunnerService

app/controllers/admin/runner_projects_controller.rb

@@ -8,7 +8,7 @@ class Admin::RunnerProjectsController < Admin::ApplicationController
   def create
     @runner = Ci::Runner.find(params[:runner_project][:runner_id])
 
-    if @runner.assign_to(@project, current_user)
+    if ::Ci::AssignRunnerService.new(@runner, @project, current_user).execute
       redirect_to edit_admin_runner_url(@runner), notice: s_('Runners|Runner assigned to project.')
     else
       redirect_to edit_admin_runner_url(@runner), alert: 'Failed adding runner to project'

app/controllers/projects/runner_projects_controller.rb

@@ -14,7 +14,7 @@ class Projects::RunnerProjectsController < Projects::ApplicationController
 
     path = project_runners_path(project)
 
-    if @runner.assign_to(project, current_user)
+    if ::Ci::AssignRunnerService.new(@runner, @project, current_user).execute
       redirect_to path, notice: s_('Runners|Runner assigned to project.')
     else
       assign_to_messages = @runner.errors.messages[:assign_to]

app/services/ci/assign_runner_service.rb

+# frozen_string_literal: true
+
+module Ci
+  class AssignRunnerService
+    # @param [Ci::Runner] runner the runner to assign to a project
+    # @param [Project] project the new project to assign the runner to
+    # @param [User] user the user performing the operation
+    def initialize(runner, project, user)
+      @runner = runner
+      @project = project
+      @user = user
+    end
+
+    def execute
+      return false unless @user.nil? || @user.can?(:assign_runner, @runner)
+
+      @runner.assign_to(@project, @user)
+    end
+  end
+end

lib/api/ci/runners.rb

@@ -187,7 +187,7 @@ module API
           runner = get_runner(params[:runner_id])
           authenticate_enable_runner!(runner)
 
-          if runner.assign_to(user_project)
+          if ::Ci::AssignRunnerService.new(runner, user_project, current_user).execute
             present runner, with: Entities::Ci::Runner
           else
             render_validation_error!(runner)

spec/services/ci/assign_runner_service_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe ::Ci::AssignRunnerService, '#execute' do
+  subject { described_class.new(runner, project, user).execute }
+
+  let_it_be(:runner) { build(:ci_runner) }
+  let_it_be(:project) { build(:project) }
+
+  context 'without user' do
+    let(:user) { nil }
+
+    it 'calls assign_to on runner and returns value unchanged' do
+      expect(runner).to receive(:assign_to).with(project, nil).once.and_return('assign_to return value')
+
+      is_expected.to eq('assign_to return value')
+    end
+  end
+
+  context 'with unauthorized user' do
+    let(:user) { build(:user) }
+
+    it 'does not call assign_to on runner and returns false' do
+      expect(runner).not_to receive(:assign_to)
+
+      is_expected.to eq(false)
+    end
+  end
+
+  context 'with admin user', :enable_admin_mode do
+    let(:user) { create_default(:user, :admin) }
+
+    it 'calls assign_to on runner and returns value unchanged' do
+      expect(runner).to receive(:assign_to).with(project, user).once.and_return('assign_to return value')
+
+      is_expected.to eq('assign_to return value')
+    end
+  end
+end