core/rawdb: simplify TestDiskSeek to use memorydb (ethereum#25182)

core/state/snapshot/disklayer_test.go

@@ -18,15 +18,11 @@ package snapshot
 
 import (
 	"bytes"
-	"io/ioutil"
-	"os"
 	"testing"
 
 	"github.com/VictoriaMetrics/fastcache"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/rawdb"
-	"github.com/ethereum/go-ethereum/ethdb"
-	"github.com/ethereum/go-ethereum/ethdb/leveldb"
 	"github.com/ethereum/go-ethereum/ethdb/memorydb"
 	"github.com/ethereum/go-ethereum/rlp"
 )
@@ -518,18 +514,7 @@ func TestDiskMidAccountPartialMerge(t *testing.T) {
 // TestDiskSeek tests that seek-operations work on the disk layer
 func TestDiskSeek(t *testing.T) {
 	// Create some accounts in the disk layer
-	var db ethdb.Database
-
-	if dir, err := ioutil.TempDir("", "disklayer-test"); err != nil {
-		t.Fatal(err)
-	} else {
-		defer os.RemoveAll(dir)
-		diskdb, err := leveldb.New(dir, 256, 0, "", false)
-		if err != nil {
-			t.Fatal(err)
-		}
-		db = rawdb.NewDatabase(diskdb)
-	}
+	db := rawdb.NewMemoryDatabase()
 	// Fill even keys [0,2,4...]
 	for i := 0; i < 0xff; i += 2 {
 		acc := common.Hash{byte(i)}