Fix WorkshopsController#rsvp 500 when member already has a nil-attending invitation

app/controllers/workshops_controller.rb

@@ -44,9 +44,10 @@ def find_attending_invitation(workshop, user)
   end
 
   def find_or_create_invitation(workshop, user, role)
-    WorkshopInvitation.create_or_find_by(workshop: workshop,
-                                         member: user,
-                                         role: role)
+    invitation = WorkshopInvitation.create_or_find_by(workshop:,
+                                                      member: user,
+                                                      role:)
+    invitation.persisted? ? invitation : WorkshopInvitation.find_by(workshop:, member: user, role:)
   end
 
   def user_attending_or_waitlisted?(workshop, user)

spec/controllers/workshops_controller_spec.rb

@@ -0,0 +1,50 @@
+RSpec.describe WorkshopsController do
+  let(:member) { Fabricate(:member) }
+  let(:workshop) { Fabricate(:workshop) }
+
+  before { login(member) }
+
+  describe 'POST #rsvp' do
+    context 'when the member already has an invitation for the workshop and role with attending nil' do
+      let!(:invitation) do
+        Fabricate(:workshop_invitation, workshop: workshop, member: member, role: 'Coach', attending: nil)
+      end
+
+      it 'redirects to the existing invitation page' do
+        post :rsvp, params: { id: workshop.id, role: 'Coach' }
+
+        expect(response).to redirect_to(invitation_path(invitation))
+      end
+
+      it 'does not create a new invitation' do
+        expect do
+          post :rsvp, params: { id: workshop.id, role: 'Coach' }
+        end.not_to change(WorkshopInvitation, :count)
+      end
+    end
+
+    context 'when the member does not have an invitation for the workshop and role' do
+      it 'creates a new invitation and redirects' do
+        expect do
+          post :rsvp, params: { id: workshop.id, role: 'Coach' }
+        end.to change(WorkshopInvitation, :count).by(1)
+
+        invitation = WorkshopInvitation.last
+        expect(response).to redirect_to(invitation_path(invitation))
+      end
+    end
+
+    context 'when the member is already attending' do
+      before do
+        Fabricate(:attending_workshop_invitation, workshop: workshop, member: member, role: 'Coach')
+      end
+
+      it 'redirects back with already wish to attend message' do
+        post :rsvp, params: { id: workshop.id, role: 'Coach' }
+
+        expect(response).to redirect_to(root_path)
+        expect(flash[:notice]).to eq(I18n.t('workshops.already_wish_to_attend'))
+      end
+    end
+  end
+end