feat: add host management methods to WorkshopSponsor

Adds methods for managing sponsor host status:
- set_as_host! - designates sponsor as workshop host
- remove_as_host! - removes host designation

Includes unit tests.

Author: mroderick

app/models/workshop_sponsor.rb

@@ -3,4 +3,12 @@ class WorkshopSponsor < ApplicationRecord
   belongs_to :workshop
 
   validates :sponsor_id, uniqueness: { scope: :workshop_id, message: :already_sponsoring }
+
+  def set_as_host!
+    update!(host: true)
+  end
+
+  def remove_as_host!
+    update!(host: false)
+  end
 end

spec/models/workshop_sponsor_spec.rb

@@ -1,9 +1,37 @@
 RSpec.describe WorkshopSponsor do
   context 'validates' do
     it 'sponsor_id for uniqueness' do
-      is_expected.to validate_uniqueness_of(:sponsor_id)
+      expect(subject).to validate_uniqueness_of(:sponsor_id)
         .scoped_to(:workshop_id)
         .with_message('already a sponsor')
     end
   end
+
+  describe '#set_as_host!' do
+    let(:workshop_sponsor) { Fabricate(:workshop_sponsor, host: false) }
+
+    it 'sets host to true' do
+      workshop_sponsor.set_as_host!
+      expect(workshop_sponsor.reload.host).to be true
+    end
+
+    it 'raises RecordInvalid on validation failure' do
+      allow(workshop_sponsor).to receive(:valid?).and_return(false)
+      expect { workshop_sponsor.set_as_host! }.to raise_error(ActiveRecord::RecordInvalid)
+    end
+  end
+
+  describe '#remove_as_host!' do
+    let(:workshop_sponsor) { Fabricate(:workshop_sponsor, host: true) }
+
+    it 'sets host to false' do
+      workshop_sponsor.remove_as_host!
+      expect(workshop_sponsor.reload.host).to be false
+    end
+
+    it 'raises RecordInvalid on validation failure' do
+      allow(workshop_sponsor).to receive(:valid?).and_return(false)
+      expect { workshop_sponsor.remove_as_host! }.to raise_error(ActiveRecord::RecordInvalid)
+    end
+  end
 end