Add test for instance clusters

Fixed a bug uncovered where we need to refer to top-level `::Project`
constant.

app/services/clusters/update_service.rb

@@ -44,7 +44,7 @@ module Clusters
     end
 
     def management_project_scope(cluster)
-      return Project.all if cluster.instance_type?
+      return ::Project.all if cluster.instance_type?
 
       group =
         if cluster.group_type?

spec/services/clusters/update_service_spec.rb

@@ -92,8 +92,6 @@ describe Clusters::UpdateService do
     end
 
     context 'when params includes :management_project_id' do
-      let(:management_project) { create(:project, namespace: cluster.first_project.namespace) }
-
       context 'management_project is non-existent' do
         let(:params) do
           { management_project_id: 0 }
@@ -109,19 +107,42 @@ describe Clusters::UpdateService do
         end
       end
 
-      context 'user is authorized to adminster manangement_project' do
-        before do
-          management_project.add_maintainer(cluster.user)
-        end
+      shared_examples 'setting a management project' do
+        context 'user is authorized to adminster manangement_project' do
+          before do
+            management_project.add_maintainer(cluster.user)
+          end
 
-        let(:params) do
-          { management_project_id: management_project.id }
+          let(:params) do
+            { management_project_id: management_project.id }
+          end
+
+          it 'updates management_project_id' do
+            is_expected.to eq(true)
+
+            expect(cluster.management_project).to eq(management_project)
+          end
         end
 
-        it 'updates management_project_id' do
-          is_expected.to eq(true)
+        context 'user is not authorized to adminster manangement_project' do
+          let(:params) do
+            { management_project_id: management_project.id }
+          end
 
-          expect(cluster.management_project).to eq(management_project)
+          it 'does not update management_project_id' do
+            is_expected.to eq(false)
+
+            expect(cluster.errors[:management_project_id]).to include('Project does not exist or you don\'t have permission to perform this action')
+
+            cluster.reload
+            expect(cluster.management_project_id).to be_nil
+          end
+        end
+      end
+
+      context 'project cluster' do
+        include_examples 'setting a management project' do
+          let(:management_project) { create(:project, namespace: cluster.first_project.namespace) }
         end
 
         context 'manangement_project is outside of the namespace scope' do
@@ -129,6 +150,10 @@ describe Clusters::UpdateService do
             management_project.update(group: create(:group))
           end
 
+          let(:params) do
+            { management_project_id: management_project.id }
+          end
+
           it 'does not update management_project_id' do
             is_expected.to eq(false)
 
@@ -140,18 +165,38 @@ describe Clusters::UpdateService do
         end
       end
 
-      context 'user is not authorized to adminster manangement_project' do
-        let(:params) do
-          { management_project_id: management_project.id }
+      context 'group cluster' do
+        let(:cluster) { create(:cluster, :group) }
+
+        include_examples 'setting a management project' do
+          let(:management_project) { create(:project, group: cluster.first_group) }
         end
 
-        it 'does not update management_project_id' do
-          is_expected.to eq(false)
+        context 'manangement_project is outside of the namespace scope' do
+          before do
+            management_project.update(group: create(:group))
+          end
 
-          expect(cluster.errors[:management_project_id]).to include('Project does not exist or you don\'t have permission to perform this action')
+          let(:params) do
+            { management_project_id: management_project.id }
+          end
 
-          cluster.reload
-          expect(cluster.management_project_id).to be_nil
+          it 'does not update management_project_id' do
+            is_expected.to eq(false)
+
+            expect(cluster.errors[:management_project_id]).to include('Project does not exist or you don\'t have permission to perform this action')
+
+            cluster.reload
+            expect(cluster.management_project_id).to be_nil
+          end
+        end
+      end
+
+      context 'instance cluster' do
+        let(:cluster) { create(:cluster, :instance) }
+
+        include_examples 'setting a management project' do
+          let(:management_project) { create(:project) }
         end
       end
     end