Monkey-patching an ActiveRecord connection to test a query optimization

gistfile1.txt

     it "does only one query" do
        connection = Dest::Base.connection
        def connection.query_count
          @query_count || 0
        end
        def connection.exec_query(*args)
          @query_count ||= 0
          @query_count += 1
          super
        end
        migration_tracker.unless_migrated(source_row_1) {}
        migration_tracker.unless_migrated(source_row_2) {}
        expect(connection.query_count).to eq 1
      end