Allow students to view the preview projects

app/models/ability.rb

@@ -23,7 +23,12 @@ def initialize(user)
   private
 
   def define_common_non_student_abilities(user)
-    return if user&.student?
+    if user&.student?
+      # Allow students to view the Experience CS preview starter template.
+      can :show, Project, user_id: nil, school_id: nil, project_type: Project::Types::CODE_EDITOR_SCRATCH
+      can :show, Component, project: { user_id: nil, school_id: nil, project_type: Project::Types::CODE_EDITOR_SCRATCH }
+      return
+    end
 
     # Anyone can view projects not owned by a user or a school.
     can :show, Project, user_id: nil, school_id: nil

spec/models/ability_spec.rb

@@ -147,6 +147,34 @@
       end
     end
 
+    context 'with a persisted school student' do
+      let(:school) { create(:school) }
+      let(:user) { create(:user, id: user_id) }
+      let(:public_scratch_starter) do
+        build(:project,
+              user_id: nil,
+              school_id: nil,
+              project_type: Project::Types::CODE_EDITOR_SCRATCH)
+      end
+      let(:public_python_starter) do
+        build(:project,
+              user_id: nil,
+              school_id: nil,
+              project_type: Project::Types::PYTHON)
+      end
+      let(:public_scratch_component) { build(:component, project: public_scratch_starter) }
+      let(:public_python_component) { build(:component, project: public_python_starter) }
+
+      before do
+        create(:student_role, user_id: user.id, school:)
+      end
+
+      it { is_expected.to be_able_to(:show, public_scratch_starter) }
+      it { is_expected.not_to be_able_to(:show, public_python_starter) }
+      it { is_expected.to be_able_to(:show, public_scratch_component) }
+      it { is_expected.not_to be_able_to(:show, public_python_component) }
+    end
+
     context 'with an experience-cs admin' do
       let(:user) { build(:experience_cs_admin_user, id: user_id) }
       let(:another_project) { build(:project) }