Check person relationship

app/interactors/accept_as_supporter.rb

@@ -4,6 +4,7 @@ class AcceptAsSupporter
   include Interactor
 
   around :wrap_into_transaction
+  before :validate_person
   before :validate_account
   after :reload_records
 
@@ -28,6 +29,10 @@ private
     context.person.reload
   end
 
+  def validate_person
+    context.fail! unless context.person.current_relationship.nil?
+  end
+
   def validate_account
     context.fail! unless context.initiator_account.can_initiate_relationship? \
       context.regional_office

spec/interactors/accept_as_supporter_spec.rb

@@ -37,6 +37,36 @@ RSpec.describe AcceptAsSupporter do
     )
   end
 
+  context 'when person is a supporter' do
+    let!(:person) { create :supporter_person }
+
+    specify { expect(subject).to be_failure }
+
+    specify do
+      expect { subject }.not_to change(Relationship, :count)
+    end
+  end
+
+  context 'when person is a member' do
+    let!(:person) { create :member_person }
+
+    specify { expect(subject).to be_failure }
+
+    specify do
+      expect { subject }.not_to change(Relationship, :count)
+    end
+  end
+
+  context 'when person is excluded' do
+    let!(:person) { create :excluded_person }
+
+    specify { expect(subject).to be_failure }
+
+    specify do
+      expect { subject }.not_to change(Relationship, :count)
+    end
+  end
+
   context 'when initiator is a federal secretary' do
     let!(:initiator_account) { create :personal_account }