test: use T.TempDir to create temporary test directory

The directory created by `T.TempDir` is automatically removed when the
test and all its subtests complete.

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

node/repo/fsrepo_test.go

@@ -2,16 +2,11 @@
 package repo
 
 import (
-	"io/ioutil"
-	"os"
 	"testing"
 )
 
-func genFsRepo(t *testing.T) (*FsRepo, func()) {
-	path, err := ioutil.TempDir("", "lotus-repo-")
-	if err != nil {
-		t.Fatal(err)
-	}
+func genFsRepo(t *testing.T) *FsRepo {
+	path := t.TempDir()
 
 	repo, err := NewFS(path)
 	if err != nil {
@@ -22,13 +17,10 @@ func genFsRepo(t *testing.T) (*FsRepo, func()) {
 	if err != ErrRepoExists && err != nil {
 		t.Fatal(err)
 	}
-	return repo, func() {
-		_ = os.RemoveAll(path)
-	}
+	return repo
 }
 
 func TestFsBasic(t *testing.T) {
-	repo, closer := genFsRepo(t)
-	defer closer()
+	repo := genFsRepo(t)
 	basicTest(t, repo)
 }