disallows reserved usernames

app/controllers/discourse_donations/charges_controller.rb

@@ -15,6 +15,8 @@ module DiscourseDonations
         end
         if params[:username].nil?
           output['messages'] << 'Please enter a username'
+        elsif ::User.reserved_username?(params[:username])
+          output['messages'] << I18n.t('login.reserved_username')
         end
       end
 

spec/controllers/discourse_donations/charges_controller_spec.rb

@@ -18,17 +18,6 @@ module DiscourseDonations
       expect(response).to have_http_status(200)
     end
 
-    it 'responds with a message when the email is empty' do
-      post :create, { create_account: 'true', email: '' }
-      expect(body['messages']).to include('Please enter your email address')
-    end
-
-    it 'responds ok when the email is empty' do
-      post :create, { create_account: 'true' }
-      expect(body['messages']).to include('Please enter your email address')
-      expect(response).to have_http_status(200)
-    end
-
     it 'expects a username if accounts are being created' do
       post :create, { email: 'zipitydoodah@example.com', create_account: 'true' }
       expect(body['messages']).to include('Please enter a username')
@@ -42,6 +31,24 @@ module DiscourseDonations
       expect(response).to have_http_status(200)
     end
 
+    describe 'new user' do
+      it 'has a message when the email is empty' do
+        post :create, { create_account: 'true', email: '' }
+        expect(body['messages']).to include('Please enter your email address')
+      end
+
+      it 'has a message when the email is empty' do
+        post :create, { create_account: 'true' }
+        expect(body['messages']).to include('Please enter your email address')
+      end
+
+      it 'has a message when the username is reserved' do
+        User.expects(:reserved_username?).returns(true)
+        post :create, { username: 'admin', create_account: 'true', email: 'something@example.com' }
+        expect(body['messages']).to include(I18n.t('login.reserved_username'))
+      end
+    end
+
     describe 'rewards' do
       let(:group_name) { 'Zasch' }
       let(:badge_name) { 'Beanie' }