Allow creating & showing remix for scratch project

The extends the `project_type` param mechanism introduced in #513 into
the `Api::Projects::RemixesController` so that the experience-cs app [1]
can create a remix of a Scratch project and then load the remix. See
this pull request [2] for more details.

[1]: https://github.com/RaspberryPiFoundation/experience-cs
[2]: RaspberryPiFoundation/experience-cs#290

Author: floehopper

app/controllers/api/projects/remixes_controller.rb

@@ -36,14 +36,18 @@ def create
       private
 
       def project
-        @project ||= Project.find_by!(identifier: params[:project_id])
+        @project ||= project_scope.find_by!(identifier: params[:project_id])
       end
 
       def load_and_authorize_remix
-        @project = Project.find_by!(remixed_from_id: project.id, user_id: current_user&.id)
+        @project = project_scope.find_by!(remixed_from_id: project.id, user_id: current_user&.id)
         authorize! :show, @project
       end
 
+      def project_scope
+        Project.only_scratch(params[:project_type] == Project::Types::SCRATCH)
+      end
+
       def remix_params
         params.require(:project)
               .permit(:name,

spec/requests/projects/remix_spec.rb

@@ -3,7 +3,8 @@
 require 'rails_helper'
 
 RSpec.describe 'Remix requests' do
-  let!(:original_project) { create(:project) }
+  let!(:original_project) { create(:project, project_type: original_project_type) }
+  let(:original_project_type) { Project::Types::PYTHON }
   let(:project_params) do
     {
       name: original_project.name,
@@ -53,8 +54,10 @@
     end
 
     describe '#show' do
+      let(:project_type) { Project::Types::PYTHON }
+
       before do
-        create(:project, remixed_from_id: original_project.id, user_id: authenticated_user.id)
+        create(:project, remixed_from_id: original_project.id, user_id: authenticated_user.id, project_type:)
       end
 
       it 'returns success response' do
@@ -68,6 +71,23 @@
 
         expect(response).to have_http_status(:not_found)
       end
+
+      context 'when original project and remix are scratch projects' do
+        let(:original_project_type) { Project::Types::SCRATCH }
+        let(:project_type) { Project::Types::SCRATCH }
+
+        it 'returns 404 response if scratch projects are not explicitly included' do
+          get("/api/projects/#{original_project.identifier}/remix", headers:)
+
+          expect(response).to have_http_status(:not_found)
+        end
+
+        it 'returns success response if scratch projects are explicitly included' do
+          get("/api/projects/#{original_project.identifier}/remix?project_type=scratch", headers:)
+
+          expect(response).to have_http_status(:ok)
+        end
+      end
     end
 
     describe '#create' do
@@ -104,6 +124,22 @@
           expect(response.body).to eq({ error: 'Something went wrong' }.to_json)
         end
       end
+
+      context 'when original project is scratch project' do
+        let(:original_project_type) { Project::Types::SCRATCH }
+
+        it 'returns 404 response if scratch projects are not explicitly included' do
+          post("/api/projects/#{original_project.identifier}/remix", params: { project: project_params }, headers:)
+
+          expect(response).to have_http_status(:not_found)
+        end
+
+        it 'returns success response if scratch projects are explicitly included' do
+          post("/api/projects/#{original_project.identifier}/remix?project_type=scratch", params: { project: project_params }, headers:)
+
+          expect(response).to have_http_status(:ok)
+        end
+      end
     end
   end