pkg/system: use t.TempDir(), remove some test-utils

With t.TempDir(), some of the test-utilities became so small that
it was more transparent to inline them. This also helps separating
concenrs, as we're in the process of thinning out and decoupling
some packages.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

pkg/system/chtimes_linux_test.go

@@ -2,6 +2,7 @@ package system // import "github.com/docker/docker/pkg/system"
 
 import (
 	"os"
+	"path/filepath"
 	"syscall"
 	"testing"
 	"time"
@@ -9,8 +10,10 @@ import (
 
 // TestChtimesLinux tests Chtimes access time on a tempfile on Linux
 func TestChtimesLinux(t *testing.T) {
-	file, dir := prepareTempFile(t)
-	defer os.RemoveAll(dir)
+	file := filepath.Join(t.TempDir(), "exist")
+	if err := os.WriteFile(file, []byte("hello"), 0o644); err != nil {
+		t.Fatal(err)
+	}
 
 	beforeUnixEpochTime := unixEpochTime.Add(-100 * time.Second)
 	afterUnixEpochTime := unixEpochTime.Add(100 * time.Second)

pkg/system/chtimes_test.go

@@ -7,24 +7,12 @@ import (
 	"time"
 )
 
-// prepareTempFile creates a temporary file in a temporary directory.
-func prepareTempFile(t *testing.T) (string, string) {
-	dir, err := os.MkdirTemp("", "docker-system-test")
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	file := filepath.Join(dir, "exist")
-	if err := os.WriteFile(file, []byte("hello"), 0644); err != nil {
-		t.Fatal(err)
-	}
-	return file, dir
-}
-
 // TestChtimes tests Chtimes on a tempfile. Test only mTime, because aTime is OS dependent
 func TestChtimes(t *testing.T) {
-	file, dir := prepareTempFile(t)
-	defer os.RemoveAll(dir)
+	file := filepath.Join(t.TempDir(), "exist")
+	if err := os.WriteFile(file, []byte("hello"), 0o644); err != nil {
+		t.Fatal(err)
+	}
 
 	beforeUnixEpochTime := unixEpochTime.Add(-100 * time.Second)
 	afterUnixEpochTime := unixEpochTime.Add(100 * time.Second)

pkg/system/chtimes_windows_test.go

@@ -5,6 +5,7 @@ package system // import "github.com/docker/docker/pkg/system"
 
 import (
 	"os"
+	"path/filepath"
 	"syscall"
 	"testing"
 	"time"
@@ -12,8 +13,10 @@ import (
 
 // TestChtimesWindows tests Chtimes access time on a tempfile on Windows
 func TestChtimesWindows(t *testing.T) {
-	file, dir := prepareTempFile(t)
-	defer os.RemoveAll(dir)
+	file := filepath.Join(t.TempDir(), "exist")
+	if err := os.WriteFile(file, []byte("hello"), 0o644); err != nil {
+		t.Fatal(err)
+	}
 
 	beforeUnixEpochTime := unixEpochTime.Add(-100 * time.Second)
 	afterUnixEpochTime := unixEpochTime.Add(100 * time.Second)

pkg/system/lstat_unix_test.go

@@ -5,13 +5,17 @@ package system // import "github.com/docker/docker/pkg/system"
 
 import (
 	"os"
+	"path/filepath"
 	"testing"
 )
 
 // TestLstat tests Lstat for existing and non existing files
 func TestLstat(t *testing.T) {
-	file, invalid, _, dir := prepareFiles(t)
-	defer os.RemoveAll(dir)
+	tmpDir := t.TempDir()
+	file := filepath.Join(tmpDir, "exist")
+	if err := os.WriteFile(file, []byte("hello"), 0o644); err != nil {
+		t.Fatal(err)
+	}
 
 	statFile, err := Lstat(file)
 	if err != nil {
@@ -21,7 +25,7 @@ func TestLstat(t *testing.T) {
 		t.Fatal("returned empty stat for existing file")
 	}
 
-	statInvalid, err := Lstat(invalid)
+	statInvalid, err := Lstat(filepath.Join(tmpDir, "nosuchfile"))
 	if err == nil {
 		t.Fatal("did not return error for non-existing file")
 	}

pkg/system/stat_unix_test.go

@@ -5,6 +5,7 @@ package system // import "github.com/docker/docker/pkg/system"
 
 import (
 	"os"
+	"path/filepath"
 	"syscall"
 	"testing"
 
@@ -13,8 +14,10 @@ import (
 
 // TestFromStatT tests fromStatT for a tempfile
 func TestFromStatT(t *testing.T) {
-	file, _, _, dir := prepareFiles(t)
-	defer os.RemoveAll(dir)
+	file := filepath.Join(t.TempDir(), "exist")
+	if err := os.WriteFile(file, []byte("hello"), 0o644); err != nil {
+		t.Fatal(err)
+	}
 
 	stat := &syscall.Stat_t{}
 	err := syscall.Lstat(file, stat)

pkg/system/utimes_unix_test.go

@@ -11,30 +11,26 @@ import (
 )
 
 // prepareFiles creates files for testing in the temp directory
-func prepareFiles(t *testing.T) (string, string, string, string) {
-	dir, err := os.MkdirTemp("", "docker-system-test")
-	if err != nil {
+func prepareFiles(t *testing.T) (file, invalid, symlink string) {
+	t.Helper()
+	dir := t.TempDir()
+
+	file = filepath.Join(dir, "exist")
+	if err := os.WriteFile(file, []byte("hello"), 0o644); err != nil {
 		t.Fatal(err)
 	}
 
-	file := filepath.Join(dir, "exist")
-	if err := os.WriteFile(file, []byte("hello"), 0644); err != nil {
-		t.Fatal(err)
-	}
-
-	invalid := filepath.Join(dir, "doesnt-exist")
-
-	symlink := filepath.Join(dir, "symlink")
+	invalid = filepath.Join(dir, "doesnt-exist")
+	symlink = filepath.Join(dir, "symlink")
 	if err := os.Symlink(file, symlink); err != nil {
 		t.Fatal(err)
 	}
 
-	return file, invalid, symlink, dir
+	return file, invalid, symlink
 }
 
 func TestLUtimesNano(t *testing.T) {
-	file, invalid, symlink, dir := prepareFiles(t)
-	defer os.RemoveAll(dir)
+	file, invalid, symlink := prepareFiles(t)
 
 	before, err := os.Stat(file)
 	if err != nil {