}
	_, err = conn.Write([]byte("GET /?underwrite=1 HTTP/1.1\r\nHost: foo\r\n\r\n"))
	if err != nil {
		t.Fatalf("error writing: %v", err)
	}

	// The ReadAll will hang for a failing test.
	got, _ := io.ReadAll(conn)
	expectedSuffix := "\r\n\r\ntoo short"
	if !strings.HasSuffix(string(got), expectedSuffix) {
		t.Errorf("Expected output to end with %q; got response body %q",