[#92] relying on subject to ensure correct class in test

spec/examples/generic_adapter_examples.rb

@@ -30,7 +30,7 @@
     it 'ensures apartment_adapter is properly set during init' do
       Thread.current[:apartment_adapter] = Apartment::Adapters::AbstractAdapter.new(config)
       Apartment::Railtie.config.to_prepare_blocks.map(&:call)
-      expect(Apartment::Tenant.adapter.class.name).to eq 'Apartment::Adapters::PostgresqlAdapter'
+      expect(Apartment::Tenant.adapter.class.name).to eq subject.class.name
     end
   end