Stop transition failed errors

app/models/school_project.rb

@@ -40,7 +40,7 @@ def returned?
     state_machine.in_state?(:returned)
   end
 
-  delegate :can_transition_to?, :history, to: :state_machine
+  delegate :can_transition_to?, :history, :in_state?, to: :state_machine
 
   private
 

lib/concepts/school_project/set_status.rb

@@ -4,14 +4,32 @@ class SchoolProject
   class SetStatus
     class << self
       def call(school_project:, status:, user_id:)
-        response = OperationResponse.new
-        response[:school_project] = school_project
-        response[:school_project].transition_status_to!(status, user_id)
-        response
-      rescue StandardError => e
-        Sentry.capture_exception(e)
-        response[:error] = e.message
-        response
+        retry_on(Statesman::TransitionConflictError, attempts: 2, record: school_project) do
+          response = OperationResponse.new
+          response[:school_project] = school_project
+
+          return response if school_project.in_state?(status)
+
+          unless school_project.can_transition_to?(status)
+            message = "Cannot transition from '#{school_project.status}' to '#{status}'"
+            response[:error] = message
+            return response
+          end
+
+          school_project.transition_status_to!(status, user_id)
+          response
+        end
+      end
+
+      private
+
+      def retry_on(exception_class, attempts:, record:)
+        yield
+      rescue exception_class
+        record.reload
+        attempts -= 1
+        retry if attempts.positive?
+        raise
       end
     end
   end

spec/concepts/school_project/set_status_spec.rb

@@ -9,42 +9,54 @@
   let(:school_project) { create(:school_project, school:, project:) }
 
   describe '.call' do
-    context 'when status transition is successful' do
-      it 'returns a successful operation response' do
-        response = described_class.call(school_project:, status: :submitted, user_id: student.id)
-        expect(response.success?).to be(true)
-      end
+    it 'returns a successful operation response' do
+      response = described_class.call(school_project:, status: :submitted, user_id: student.id)
+      expect(response.success?).to be(true)
+    end
 
-      it 'updates the school project status' do
-        described_class.call(school_project:, status: :submitted, user_id: student.id)
-        expect(school_project.status).to eq('submitted')
-      end
+    it 'updates the school project status' do
+      described_class.call(school_project:, status: :submitted, user_id: student.id)
+      expect(school_project.status).to eq('submitted')
+    end
 
-      it 'returns the updated school project in the response' do
-        response = described_class.call(school_project:, status: :submitted, user_id: student.id)
-        expect(response[:school_project]).to be_a(SchoolProject)
-      end
+    it 'returns the updated school project in the response' do
+      response = described_class.call(school_project:, status: :submitted, user_id: student.id)
+      expect(response[:school_project]).to be_a(SchoolProject)
     end
 
-    context 'when status transition fails' do
-      before do
-        allow(school_project).to receive(:transition_status_to!).and_raise(StandardError, 'Transition failed')
-      end
+    it 'returns an error when transitioning to an invalid status' do
+      response = described_class.call(school_project:, status: :returned, user_id: student.id)
+      expect(response.success?).to be(false)
+      expect(response[:error]).to eq("Cannot transition from '#{school_project.status}' to 'returned'")
+    end
 
-      it 'returns a failed operation response' do
-        response = described_class.call(school_project:, status: :submitted, user_id: student.id)
-        expect(response.success?).to be(false)
-      end
+    it 'is successful when transitioning to the same status' do
+      school_project.transition_status_to!(:submitted, student.id)
+      response = described_class.call(school_project:, status: :submitted, user_id: student.id)
+      expect(response.success?).to be(true)
+      expect(school_project.status).to eq('submitted')
+    end
 
-      it 'does not update the school project status' do
-        described_class.call(school_project:, status: :submitted, user_id: student.id)
-        expect(school_project.status).to eq('unsubmitted')
-      end
+    it 'retries when transition raises a "Statesman::TransitionConflictError" error' do
+      call_count = 0
+      allow(school_project).to receive(:transition_status_to!).and_wrap_original do |original, *args|
+        call_count += 1
+        raise Statesman::TransitionConflictError if call_count == 1
 
-      it 'includes the error message in the response' do
-        response = described_class.call(school_project:, status: :submitted, user_id: student.id)
-        expect(response[:error]).to eq('Transition failed')
+        original.call(*args)
       end
+
+      response = described_class.call(school_project:, status: :submitted, user_id: student.id)
+      expect(response.success?).to be(true)
+      expect(school_project.status).to eq('submitted')
+    end
+
+    it 'raises the "Statesman::TransitionConflictError" error after 2 attempts' do
+      allow(school_project).to receive(:transition_status_to!).and_raise(Statesman::TransitionConflictError).twice
+
+      expect do
+        described_class.call(school_project:, status: :submitted, user_id: student.id)
+      end.to raise_error(Statesman::TransitionConflictError)
     end
   end
 end

spec/features/school_project/complete_spec.rb

@@ -60,21 +60,6 @@
         expect(student_project.school_project).to be_complete
       end
     end
-
-    context 'when attempting an invalid status transition' do
-      before do
-        student_project.school_project.transition_status_to!(:complete, student.id)
-        post("/api/projects/#{student_project.identifier}/complete", headers:)
-      end
-
-      it 'completes unauthorized response' do
-        expect(response).to have_http_status(:unprocessable_content)
-      end
-
-      it 'completes error message' do
-        expect(JSON.parse(response.body)['error']).to eq("Cannot transition from 'complete' to 'complete'")
-      end
-    end
   end
 
   context 'when user does not own the project and is not the class teacher' do