network := "ip:tcp"
	if !testableNetwork(network) {
		t.Skipf("skipping %s test", network)
	}

	raddr := &IPAddr{IP: IPv4(127, 0, 0, 1).To4()}
	c, err := DialIP(network, &IPAddr{IP: IPv4(127, 0, 0, 1)}, raddr)
	if testenv.SyscallIsNotSupported(err) {
		// May be inside a container that disallows creating a socket.
		t.Skipf("skipping %s test: %v", network, err)
	} else if err != nil {
		t.Fatal(err)
	}

	"time"
)

func TestRepeatBootstrap(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping test that rebuilds the entire toolchain")
	}
	switch runtime.GOOS {
	case "android", "ios", "js", "wasip1":
		t.Skipf("skipping because the toolchain does not have to bootstrap on GOOS=%s", runtime.GOOS)
	}

	realGoroot := testenv.GOROOT(t)

	// To ensure that bootstrapping doesn't unexpectedly depend

func TestConnAndListener(t *testing.T) {
	for i, network := range []string{"tcp", "unix", "unixpacket"} {
		i, network := i, network
		t.Run(network, func(t *testing.T) {
			if !testableNetwork(network) {
				t.Skipf("skipping %s test", network)
			}

			ls := newLocalServer(t, network)
			defer ls.teardown()
			ch := make(chan error, 1)
			handler := func(ls *localServer, ln Listener) { ls.transponder(ln, ch) }

			return
		}

		b := testenv.Builder()
		if b == "" {
			// We shouldn't make assumptions about what kind of sandbox or build
			// environment external Go users may be running in.
			t.Skipf("skipping: 'go build' unavailable")
		}

		// Since we control the Go builders, we know which ones ought
		// to be able to run 'go build'. Check that they can.
		//

	})
}

// test1: shared library can be dynamically loaded and exported symbols are accessible.
func TestExportedSymbolsWithDynamicLoad(t *testing.T) {
	if GOOS == "windows" {
		t.Skipf("Skipping on %s", GOOS)
	}
	globalSkip(t)
	testenv.MustHaveCGO(t)
	testenv.MustHaveExec(t)

	t.Parallel()

	cmd := "testp1"
	bin := cmdToRun(cmd)

	createHeadersOnce(t)

	const minRlimitCore = 100 << 20 // 100 MB
	if lim.Max < minRlimitCore {
		t.Skipf("RLIMIT_CORE max too low: %#+v", lim)
	}

	// Make sure core pattern will send core to the current directory.
	b, err := os.ReadFile("/proc/sys/kernel/core_pattern")
	if err != nil {
		t.Fatalf("error reading core_pattern: %v", err)
	}
	if string(b) != "core\n" {
		t.Skipf("Unexpected core pattern %q", string(b))
	}

	coreUsesPID := false

	out, err := exec.Command("gdb", "--version").CombinedOutput()
	if err != nil {
		t.Skipf("skipping: error executing gdb: %v", err)
	}
	re := regexp.MustCompile(`([0-9]+)\.([0-9]+)`)
	matches := re.FindSubmatch(out)
	if len(matches) < 3 {
		t.Skipf("skipping: can't determine gdb version from\n%s\n", out)
	}
	major, err1 := strconv.Atoi(string(matches[1]))

	{1 * time.Millisecond, 0},
	{0, 1 * time.Millisecond},
	{1 * time.Millisecond, 5 * time.Second}, // timeout over deadline
}

func TestDialTimeout(t *testing.T) {
	switch runtime.GOOS {
	case "plan9":
		t.Skipf("not supported on %s", runtime.GOOS)
	}

	t.Parallel()

	ln := newLocalListener(t, "tcp")
	defer func() {
		if err := ln.Close(); err != nil {
			t.Error(err)
		}
	}()

	const nonPollable = "/dev/net/tun"

	f, err := os.OpenFile(nonPollable, os.O_RDWR, 0)
	if err != nil {
		if errors.Is(err, fs.ErrNotExist) || errors.Is(err, fs.ErrPermission) || testenv.SyscallIsNotSupported(err) {
			t.Skipf("can't open %q: %v", nonPollable, err)
		}
		t.Fatal(err)
	}
	f.Close()

	// On a Linux laptop, before the problem was fixed,
	// this test failed about 50% of the time with this
	// number of iterations.

// following:
//	golang.org/x/net/ipv4
//	golang.org/x/net/ipv6
//	golang.org/x/net/icmp

func TestTCPListenerSpecificMethods(t *testing.T) {
	switch runtime.GOOS {
	case "plan9":
		t.Skipf("not supported on %s", runtime.GOOS)
	}

	la, err := ResolveTCPAddr("tcp4", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	ln, err := ListenTCP("tcp4", la)
	if err != nil {
		t.Fatal(err)
	}