Add new ability check for stopping environment

app/policies/environment_policy.rb

 class EnvironmentPolicy < BasePolicy
+
+  alias_method :environment, :subject
+
   def rules
-    delegate! @subject.project
+    delegate! environment.project
+
+    if environment.stop_action?
+      delegate! environment.stop_action
+    end
+
+    if can?(:create_deployment) && can?(:play_build)
+      can! :stop_environment
+    end
   end
 end

app/services/ci/stop_environments_service.rb

@@ -5,12 +5,11 @@ module Ci
     def execute(branch_name)
       @ref = branch_name
 
-      return unless has_ref?
-      return unless can?(current_user, :create_deployment, project)
+      return unless @ref.present?
 
       environments.each do |environment|
         next unless environment.stop_action?
-        next unless can?(current_user, :play_build, environment.stop_action)
+        next unless can?(current_user, :stop_environment, environment)
 
         environment.stop_with_action!(current_user)
       end
@@ -18,10 +17,6 @@ module Ci
 
     private
 
-    def has_ref?
-      @ref.present?
-    end
-
     def environments
       @environments ||= EnvironmentsFinder
         .new(project, current_user, ref: @ref, recently_updated: true)

spec/policies/environment_policy_spec.rb

+require 'spec_helper'
+
+describe Ci::EnvironmentPolicy do
+  let(:user) { create(:user) }
+  let(:project) { create(:project) }
+
+  let(:environment) do
+    create(:environment, :with_review_app, project: project)
+  end
+
+  let(:policies) do
+    described_class.abilities(user, environment).to_set
+  end
+
+  describe '#rules' do
+    context 'when user does not have access to the project' do
+      let(:project) { create(:project, :private) }
+
+      it 'does not include ability to stop environment' do
+        expect(policies).not_to include :stop_environment
+      end
+    end
+
+    context 'when anonymous user has access to the project' do
+      let(:project) { create(:project, :public) }
+
+      it 'does not include ability to stop environment' do
+        expect(policies).not_to include :stop_environment
+      end
+    end
+
+    context 'when team member has access to the project' do
+      let(:project) { create(:project, :public) }
+
+      before do
+        project.add_master(user)
+      end
+
+      context 'when team member has ability to stop environment' do
+        it 'does includes ability to stop environment' do
+          expect(policies).to include :stop_environment
+        end
+      end
+
+      context 'when team member has no ability to stop environment' do
+        before do
+          create(:protected_branch, :no_one_can_push,
+                 name: 'master', project: project)
+        end
+
+        it 'does not include ability to stop environment' do
+          expect(policies).not_to include :stop_environment
+        end
+      end
+    end
+  end
+end