fix checking for blank UUID while importing and exporting

app/controllers/exercises_controller.rb

@@ -150,10 +150,10 @@ def import_uuid_check
     user = user_from_api_key
     return render json: {}, status: :unauthorized if user.nil?
 
-    uuid = params[:uuid]
+    uuid = params[:uuid].presence
     exercise = Exercise.find_by(uuid:)
 
-    return render json: {uuid_found: false} if exercise.nil?
+    return render json: {uuid_found: false} if uuid.blank? || exercise.nil?
     return render json: {uuid_found: true, update_right: false} unless ExercisePolicy.new(user, exercise).update?
 
     render json: {uuid_found: true, update_right: true}

app/services/exercise_service/check_external.rb

@@ -9,6 +9,8 @@ def initialize(uuid:, codeharbor_link:)
     end
 
     def execute
+      return {error: false, message: message(false, true)} if @uuid.blank?
+
       response = self.class.connection.post @codeharbor_link.check_uuid_url do |req|
         req.headers['Content-Type'] = 'application/json'
         req.headers['Authorization'] = "Bearer #{@codeharbor_link.api_key}"

spec/controllers/exercises_controller_spec.rb

@@ -459,6 +459,18 @@
         expect(response.parsed_body.symbolize_keys[:uuid_found]).to be false
       end
     end
+
+    context 'when uuid is nil' do
+      let(:exercise) { create(:dummy, uuid: nil) }
+      let(:uuid) { nil }
+
+      it 'renders correct response' do
+        post_request
+        expect(response).to have_http_status(:success)
+
+        expect(response.parsed_body.symbolize_keys[:uuid_found]).to be false
+      end
+    end
   end
 
   describe 'POST #import_task' do

spec/services/exercise_service/check_external_spec.rb

@@ -84,5 +84,17 @@
         expect(check_external_service).to eql(error: true, message: I18n.t('exercises.export_codeharbor.error'))
       end
     end
+
+    context 'with no uuid' do
+      let(:uuid) { nil }
+
+      it 'does not make a request' do
+        expect(check_external_service).not_to have_requested(:post, codeharbor_link.check_uuid_url)
+      end
+
+      it 'returns the correct hash' do
+        expect(check_external_service).to eql(error: false, message: I18n.t('exercises.export_codeharbor.check.no_task'))
+      end
+    end
   end
 end