assert_called_on_instance_of

# File activesupport/lib/active_support/testing/method_call_assertions.rb, line 51
        def assert_called_on_instance_of(klass, method_name, message = nil, times: 1, returns: nil)
          times_called = 0
          klass.define_method("stubbed_#{method_name}") do |*|
            times_called += 1

            returns
          end

          klass.alias_method "original_#{method_name}", method_name
          klass.alias_method method_name, "stubbed_#{method_name}"

          yield

          error = "Expected #{method_name} to be called #{times} times, but was called #{times_called} times"
          error = "#{message}.\n#{error}" if message

          assert_equal times, times_called, error
        ensure
          klass.alias_method method_name, "original_#{method_name}"
          klass.undef_method "original_#{method_name}"
          klass.undef_method "stubbed_#{method_name}"
        end