w.Write([]byte(r.RemoteAddr))

	// Include the address of the net.Conn in addition to the RemoteAddr,
	// in case kernels reuse source ports quickly (see Issue 52450)
	if c, ok := ResponseWriterConnForTesting(w); ok {
		fmt.Fprintf(w, ", %T %p", c, c)
	}
})

// testCloseConn is a net.Conn tracked by a testConnSet.
type testCloseConn struct {
	net.Conn
	set *testConnSet
}