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: lock_test.go
    path of file: ./repos/learning/golang/practice/go-crontab/gopath/src/github.com/coreos/etcd/pkg/fileutil
    
    the code of the file until where you have to start completion: // Copyright 2015 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distrib
    
func TestLockAndUnlock(t *testing.T) {
	f, err := ioutil.TempFile("", "lock")
	if err != nil {
		t.Fatal(err)
	}
	f.Close()
	defer func() {
		err = os.Remove(f.Name())
		if err != nil {
			t.Fatal(err)
		}
	}()

	// lock the file
	l, err := LockFile(f.Name(), os.O_WRONLY, PrivateFileMode)
	if err != nil {
		t.Fatal(err)
	}

	// try lock a locked file
	if _, err = TryLockFile(f.Name(), os.O_WRONLY, PrivateFileMode); err != ErrLocked {
		t.Fatal(err)
	}

	// unlock the file
	if err = l.Close(); err != nil {
		t.Fatal(err)
	}

	// try lock the unlocked file
	dupl, err := TryLockFile(f.Name(), os.O_WRONLY, PrivateFileMode)
	if err != nil {
		t.Errorf("err = %v, want %v", err, nil)
	}

	// blocking on locked file
	locked := make(chan struct{}, 1)
	go func() {
		bl, blerr := LockFile(f.Name(), os.O_WRONLY, PrivateFileMode)
		if blerr != nil {
			t.Fatal(blerr)
		}
		locked <- struct{}{}
		if blerr = bl.Close(); blerr != nil {
			t.Fatal(blerr)
		}
	}()

	select {
	case <-locked:
		t.Error("unexpected unblocking")
	case <-time.After(100 * time.Millisecond):
	}

	// unlock
	if err = dupl.Close(); err != nil {
		t.Fatal(err)
	}

	// the previously blocked routine should be unblocked
	select {
	case <-locked:
	case <-time.After(1 * time.Second):
		t.Error("unexpected blocking")
	}
}