You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: fs_test.go
    path of file: ./repos/gccrs/libgo/go/net/http
    
    the code of the file until where you have to start completion: // Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-st
    
func TestLinuxSendfile(t *testing.T) {
	setParallel(t)
	defer afterTest(t)
	if runtime.GOOS != "linux" {
		t.Skip("skipping; linux-only test")
	}
	if _, err := exec.LookPath("strace"); err != nil {
		t.Skip("skipping; strace not found in path")
	}

	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	lnf, err := ln.(*net.TCPListener).File()
	if err != nil {
		t.Fatal(err)
	}
	defer ln.Close()

	// Attempt to run strace, and skip on failure - this test requires SYS_PTRACE.
	if err := exec.Command("strace", "-f", "-q", os.Args[0], "-test.run=^$").Run(); err != nil {
		t.Skipf("skipping; failed to run strace: %v", err)
	}

	filename := fmt.Sprintf("1kb-%d", os.Getpid())
	filepath := path.Join(os.TempDir(), filename)

	if err := os.WriteFile(filepath, bytes.Repeat([]byte{'a'}, 1<<10), 0755); err != nil {
		t.Fatal(err)
	}
	defer os.Remove(filepath)

	var buf bytes.Buffer
	child := exec.Command("strace", "-f", "-q", os.Args[0], "-test.run=TestLinuxSendfileChild")
	child.ExtraFiles = append(child.ExtraFiles, lnf)
	child.Env = append([]string{"GO_WANT_HELPER_PROCESS=1"}, os.Environ()...)
	child.Stdout = &buf
	child.Stderr = &buf
	if err := child.Start(); err != nil {
		t.Skipf("skipping; failed to start straced child: %v", err)
	}

	res, err := Get(fmt.Sprintf("http://%s/%s", ln.Addr(), filename))
	if err != nil {
		t.Fatalf("http client error: %v", err)
	}
	_, err = io.Copy(io.Discard, res.Body)
	if err != nil {
		t.Fatalf("client body read error: %v", err)
	}
	res.Body.Close()

	// Force child to exit cleanly.
	Post(fmt.Sprintf("http://%s/quit", ln.Addr()), "", nil)
	child.Wait()

	rx := regexp.MustCompile(`\b(n64:)?sendfile(64)?\(`)
	out := buf.String()
	if !rx.MatchString(out) {
		t.Errorf("no sendfile system call found in:\n%s", out)
	}
}