refactor: move from io/ioutil to io and os package

The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

cio/io_test.go

@@ -23,7 +23,6 @@ import (
 	"bytes"
 	"context"
 	"io"
-	"io/ioutil"
 	"net/url"
 	"os"
 	"path/filepath"
@@ -50,7 +49,7 @@ func TestNewFIFOSetInDir(t *testing.T) {
 		t.Skip("NewFIFOSetInDir has different behaviour on windows")
 	}
 
-	root, err := ioutil.TempDir("", "test-new-fifo-set")
+	root, err := os.MkdirTemp("", "test-new-fifo-set")
 	assert.NilError(t, err)
 	defer os.RemoveAll(root)
 
@@ -69,12 +68,12 @@ func TestNewFIFOSetInDir(t *testing.T) {
 	}
 	assert.Assert(t, is.DeepEqual(fifos, expected, cmpFIFOSet))
 
-	files, err := ioutil.ReadDir(root)
+	files, err := os.ReadDir(root)
 	assert.NilError(t, err)
 	assert.Check(t, is.Len(files, 1))
 
 	assert.NilError(t, fifos.Close())
-	files, err = ioutil.ReadDir(root)
+	files, err = os.ReadDir(root)
 	assert.NilError(t, err)
 	assert.Check(t, is.Len(files, 0))
 }
@@ -102,19 +101,19 @@ func TestNewAttach(t *testing.T) {
 	fifos, err := NewFIFOSetInDir("", "theid", false)
 	assert.NilError(t, err)
 
-	io, err := attacher(fifos)
+	attachedFifos, err := attacher(fifos)
 	assert.NilError(t, err)
-	defer io.Close()
+	defer attachedFifos.Close()
 
-	producers := setupFIFOProducers(t, io.Config())
+	producers := setupFIFOProducers(t, attachedFifos.Config())
 	initProducers(t, producers, expectedStdout, expectedStderr)
 
-	actualStdin, err := ioutil.ReadAll(producers.Stdin)
+	actualStdin, err := io.ReadAll(producers.Stdin)
 	assert.NilError(t, err)
 
-	io.Wait()
-	io.Cancel()
-	assert.NilError(t, io.Close())
+	attachedFifos.Wait()
+	attachedFifos.Cancel()
+	assert.NilError(t, attachedFifos.Close())
 
 	assert.Check(t, is.Equal(expectedStdout, stdout.String()))
 	assert.Check(t, is.Equal(expectedStderr, stderr.String()))

cio/io_unix.go

@@ -22,7 +22,6 @@ package cio
 import (
 	"context"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sync"
@@ -39,7 +38,7 @@ func NewFIFOSetInDir(root, id string, terminal bool) (*FIFOSet, error) {
 			return nil, err
 		}
 	}
-	dir, err := ioutil.TempDir(root, "")
+	dir, err := os.MkdirTemp(root, "")
 	if err != nil {
 		return nil, err
 	}

cio/io_unix_test.go

@@ -22,7 +22,6 @@ package cio
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -66,7 +65,7 @@ func TestOpenFifosWithTerminal(t *testing.T) {
 	var ctx, cancel = context.WithCancel(context.Background())
 	defer cancel()
 
-	ioFifoDir, err := ioutil.TempDir("", fmt.Sprintf("cio-%s", t.Name()))
+	ioFifoDir, err := os.MkdirTemp("", fmt.Sprintf("cio-%s", t.Name()))
 	if err != nil {
 		t.Fatalf("unexpected error during creating temp dir: %v", err)
 	}