Improve CodeOcean::FilePolicy with specs

app/policies/code_ocean/file_policy.rb

@@ -14,7 +14,7 @@ module CodeOcean
 
     def create?
       if @record.context.is_a?(Exercise)
-        admin? # FIXME: || author?
+        admin? || author?
       elsif @record.context.is_a?(Submission) and @record.context.exercise.allow_file_creation
         author?
       else

spec/controllers/code_ocean/files_controller_spec.rb

@@ -9,7 +9,10 @@ describe CodeOcean::FilesController do
 
     context 'with a valid file' do
       let(:perform_request) { proc { post :create, params: { code_ocean_file: FactoryBot.build(:file, context: submission).attributes, format: :json } } }
-      before(:each) { perform_request.call }
+      before(:each) do
+        submission.exercise.update(allow_file_creation: true)
+        perform_request.call
+      end
 
       expect_assigns(file: CodeOcean::File)
 
@@ -22,7 +25,10 @@ describe CodeOcean::FilesController do
     end
 
     context 'with an invalid file' do
-      before(:each) { post :create, params: { code_ocean_file: {context_id: submission.id, context_type: Submission}, format: :json } }
+      before(:each) do
+        submission.exercise.update(allow_file_creation: true)
+        post :create, params: { code_ocean_file: {context_id: submission.id, context_type: Submission}, format: :json }
+      end
 
       expect_assigns(file: CodeOcean::File)
       expect_json

spec/policies/code_ocean/file_policy_spec.rb

@@ -28,8 +28,24 @@ describe CodeOcean::FilePolicy do
     context 'as part of a submission' do
       let(:file) { submission.files.first }
 
-      it 'grants access to authors' do
-        expect(subject).to permit(submission.author, file)
+      context 'where file creation is allowed' do
+        before do
+          submission.exercise.update(allow_file_creation: true)
+        end
+
+        it 'grants access to authors' do
+          expect(subject).to permit(submission.author, file)
+        end
+      end
+
+      context 'where file creation is not allowed' do
+        before do
+          submission.exercise.update(allow_file_creation: false)
+        end
+
+        it 'grants access to authors' do
+          expect(subject).not_to permit(submission.author, file)
+        end
       end
 
       it 'does not grant access to all other users' do