github.com/szq-123/codingpractice@v0.0.0-20240430111904-2778dfaf7994/golang/io_test.go (about)

     1  package golang
     2  
     3  import (
     4  	"GolangPractice/utils/logger"
     5  	"archive/zip"
     6  	"bufio"
     7  	"bytes"
     8  	"github.com/gookit/color"
     9  	"io"
    10  	"os"
    11  	"testing"
    12  )
    13  
    14  // here are some frequently used package provided by the official group.
    15  // io: basic `reader`, `writer`, etc. pipe,
    16  // os: file
    17  // bufio: reading and writing with buffer.
    18  // ioutil: read and write files. It's about to be obsolete. previous functions will be translocated to package `io`,`os`.
    19  // archive/zip: read and write compressed files with buffer.
    20  // io/fs: file system.
    21  
    22  func TestWorkDir(t *testing.T) {
    23  	// Get current work directory
    24  	workDir, err := os.Getwd()
    25  	if err != nil {
    26  		logger.Errorln(err)
    27  		return
    28  	}
    29  	logger.Infoln("workDir:", workDir)
    30  
    31  	// change current directory
    32  	err = os.Chdir("/root")
    33  	if err != nil {
    34  		logger.Errorln(err)
    35  		return
    36  	}
    37  }
    38  
    39  func TestFile(t *testing.T) {
    40  	// get user home dir
    41  	homeDir, _ := os.UserHomeDir()
    42  
    43  	// flag `os.O_CREATE` used for creating a file when not existing. you can use os.Create() instead.
    44  	f, err := os.OpenFile(homeDir+"test.txt", os.O_RDWR|os.O_CREATE, 0666)
    45  	if err != nil {
    46  		logger.Errorln("open file err:", err)
    47  		return
    48  	}
    49  	defer f.Close()
    50  
    51  	n, err := f.Write([]byte(`you are the beast!`))
    52  	if err != nil {
    53  		logger.Errorf("writing does not finish. %d bytes writed\n", n)
    54  	}
    55  
    56  	os.Remove("test1.txt")
    57  }
    58  
    59  func TestReadFile(t *testing.T) {
    60  	// METHOD 1: os.Open just for Reading.
    61  	file, err := os.Open("test.txt")
    62  	if err != nil {
    63  		logger.Errorln("open file err: ", err)
    64  		return
    65  	}
    66  	defer file.Close()
    67  
    68  	content := bytes.NewBuffer(nil)
    69  	var buf [128]byte
    70  	for {
    71  		n, err1 := file.Read(buf[:])
    72  		// complete reading file.
    73  		if err1 == io.EOF {
    74  			break
    75  		}
    76  		if err1 != nil {
    77  			logger.Errorln("read file err:", err1)
    78  			return
    79  		}
    80  		content.Write(buf[:n])
    81  	}
    82  	logger.Infoln("content:", content.String())
    83  
    84  	// METHOD 2
    85  	content1, err := os.ReadFile("test.txt")
    86  	logger.Infof("content1: %s, 				err: %s\n", content1, err.Error())
    87  }
    88  
    89  func TestZip(t *testing.T) {
    90  	// TODO
    91  	f, _ := os.OpenFile("demo.zip", os.O_RDWR|os.O_CREATE, 0666)
    92  	defer f.Close()
    93  
    94  	z := zip.NewWriter(f)
    95  	defer z.Close() // `Flush` will execute in the function.
    96  }
    97  
    98  func TestStd(t *testing.T) {
    99  	input := make([]byte, 0, 20)
   100  	_, err := os.Stdin.Read(input)
   101  	logger.Infof("input: %s, 					err: %s", input, err.Error())
   102  
   103  	_, err = os.Stdout.Write(input)
   104  	logger.Errorln("Write err:", err)
   105  
   106  	// TODO doesn't work well
   107  	// redirect output to particular file
   108  	redirectFile, err := os.OpenFile("/tmp/redirectFile", os.O_RDWR|os.O_CREATE|os.O_SYNC, 0766)
   109  	if err != nil {
   110  		color.Redln("failed to open redirectFile file, reason: ", err.Error())
   111  		return
   112  	}
   113  	defer redirectFile.Close()
   114  	os.Stdout = redirectFile
   115  	os.Stderr = redirectFile
   116  
   117  	logger.Infoln("output after redirect")
   118  }
   119  
   120  func TestBufIO(t *testing.T) {
   121  	f, err := os.OpenFile("test.txt", os.O_RDWR|os.O_CREATE, 0666)
   122  	if err != nil {
   123  		logger.Errorln("open file err: ", err)
   124  		return
   125  	}
   126  	defer f.Close()
   127  
   128  	bufWriter := bufio.NewWriter(f)
   129  	for i := 0; i < 10; i++ {
   130  		bufWriter.Write([]byte("123\n"))
   131  		bufWriter.Flush()
   132  	}
   133  
   134  	// bufio.NewReader(f) = bufio.NewReaderSize(f, 4096)
   135  	reader := bufio.NewReaderSize(f, 4096)
   136  
   137  	reader.ReadBytes('\n')
   138  }