all: use T.TempDir to create temporary test directories (#24633)

This commit replaces ioutil.TempDir with t.TempDir in tests. The
directory created by t.TempDir is automatically removed when the test
and all its subtests complete.

Prior to this commit, temporary directory created using ioutil.TempDir
had to be removed manually by calling os.RemoveAll, which is omitted in
some tests. The error handling boilerplate e.g.

	defer func() {
		if err := os.RemoveAll(dir); err != nil {
			t.Fatal(err)
		}
	}

is also tedious, but t.TempDir handles this for us nicely.

Reference: https://pkg.go.dev/testing#T.TempDir
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

cmd/geth/accountcmd_test.go

@@ -33,7 +33,7 @@ import (
 // are copied into a temporary keystore directory.
 
 func tmpDatadirWithKeystore(t *testing.T) string {
-	datadir := tmpdir(t)
+	datadir := t.TempDir()
 	keystore := filepath.Join(datadir, "keystore")
 	source := filepath.Join("..", "..", "accounts", "keystore", "testdata", "keystore")
 	if err := cp.CopyAll(keystore, source); err != nil {
@@ -111,7 +111,7 @@ func TestAccountImport(t *testing.T) {
 }
 
 func importAccountWithExpect(t *testing.T, key string, expected string) {
-	dir := tmpdir(t)
+	dir := t.TempDir()
 	keyfile := filepath.Join(dir, "key.prv")
 	if err := ioutil.WriteFile(keyfile, []byte(key), 0600); err != nil {
 		t.Error(err)

cmd/geth/consolecmd_test.go

@@ -19,7 +19,6 @@ package main
 import (
 	"crypto/rand"
 	"math/big"
-	"os"
 	"path/filepath"
 	"runtime"
 	"strconv"
@@ -92,9 +91,7 @@ func TestAttachWelcome(t *testing.T) {
 	if runtime.GOOS == "windows" {
 		ipc = `\\.\pipe\geth` + strconv.Itoa(trulyRandInt(100000, 999999))
 	} else {
-		ws := tmpdir(t)
-		defer os.RemoveAll(ws)
-		ipc = filepath.Join(ws, "geth.ipc")
+		ipc = filepath.Join(t.TempDir(), "geth.ipc")
 	}
 	// And HTTP + WS attachment
 	p := trulyRandInt(1024, 65533) // Yeah, sometimes this will fail, sorry :P
@@ -118,6 +115,7 @@ func TestAttachWelcome(t *testing.T) {
 		waitForEndpoint(t, endpoint, 3*time.Second)
 		testAttachWelcome(t, geth, endpoint, httpAPIs)
 	})
+	geth.ExpectExit()
 }
 
 func testAttachWelcome(t *testing.T, geth *testgeth, endpoint, apis string) {

cmd/geth/dao_test.go

@@ -19,7 +19,6 @@ package main
 import (
 	"io/ioutil"
 	"math/big"
-	"os"
 	"path/filepath"
 	"testing"
 
@@ -106,8 +105,7 @@ func TestDAOForkBlockNewChain(t *testing.T) {
 
 func testDAOForkBlockNewChain(t *testing.T, test int, genesis string, expectBlock *big.Int, expectVote bool) {
 	// Create a temporary data directory to use and inspect later
-	datadir := tmpdir(t)
-	defer os.RemoveAll(datadir)
+	datadir := t.TempDir()
 
 	// Start a Geth instance with the requested flags set and immediately terminate
 	if genesis != "" {

cmd/geth/genesis_test.go

@@ -18,7 +18,6 @@ package main
 
 import (
 	"io/ioutil"
-	"os"
 	"path/filepath"
 	"testing"
 )
@@ -73,8 +72,7 @@ var customGenesisTests = []struct {
 func TestCustomGenesis(t *testing.T) {
 	for i, tt := range customGenesisTests {
 		// Create a temporary data directory to use and inspect later
-		datadir := tmpdir(t)
-		defer os.RemoveAll(datadir)
+		datadir := t.TempDir()
 
 		// Initialize the data directory with the custom genesis block
 		json := filepath.Join(datadir, "genesis.json")

cmd/geth/run_test.go

@@ -19,7 +19,6 @@ package main
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"testing"
 	"time"
@@ -29,14 +28,6 @@ import (
 	"github.com/ethereum/go-ethereum/rpc"
 )
 
-func tmpdir(t *testing.T) string {
-	dir, err := ioutil.TempDir("", "geth-test")
-	if err != nil {
-		t.Fatal(err)
-	}
-	return dir
-}
-
 type testgeth struct {
 	*cmdtest.TestCmd
 
@@ -82,15 +73,9 @@ func runGeth(t *testing.T, args ...string) *testgeth {
 		}
 	}
 	if tt.Datadir == "" {
-		tt.Datadir = tmpdir(t)
-		tt.Cleanup = func() { os.RemoveAll(tt.Datadir) }
+		// The temporary datadir will be removed automatically if something fails below.
+		tt.Datadir = t.TempDir()
 		args = append([]string{"--datadir", tt.Datadir}, args...)
-		// Remove the temporary datadir if something fails below.
-		defer func() {
-			if t.Failed() {
-				tt.Cleanup()
-			}
-		}()
 	}
 
 	// Boot "geth". This actually runs the test binary but the TestMain