diff --git a/main.go b/main.go
index 2b165c1f..65ed4fd5 100644
--- a/main.go
+++ b/main.go
@@ -113,9 +113,8 @@ func (s *DB) DataSource() string {
 func (s *DB) CopyDB() (*sql.DB, error) {
 	if s.copyDB != nil {
 		return s.copyDB, nil
-	} else {
-		return sql.Open(s.Dialect().GetName(), s.DataSource())
 	}
+		return sql.Open(s.Dialect().GetName(), s.DataSource())
 }
 
 type closer interface {
diff --git a/main_test.go b/main_test.go
index dbcd8621..62e798b1 100644
--- a/main_test.go
+++ b/main_test.go
@@ -1061,15 +1061,24 @@ func TestBlockGlobalUpdate(t *testing.T) {
 
 func TestDB_DataSource(t *testing.T) {
 	source := "user=gorm password=gorm DB.name=gorm port=9920 sslmode=disable"
-	if DB.DataSource() != source {
-		t.Fatal(fmt.Sprintf("want '%s', but got '%s'", source, DB.DataSource()))
+	db,er := gorm.Open("postgres", source)
+	if er!=nil {
+		panic(fmt.Sprintf("No error should happen when connecting to test database, but got err=%+v", er))
+	}
+	if db.DataSource() != source {
+		t.Fatal(fmt.Sprintf("want '%s', but got '%s'", source, db.DataSource()))
 	}
 
 }
 func TestDB_CopyIn(t *testing.T) {
-	e:=DB.Exec("create table if not exists example(name varchar, age integer)").Error
+	source := "user=gorm password=gorm DB.name=gorm port=9920 sslmode=disable"
+	db,er := gorm.Open("postgres", source)
+	if er!=nil {
+		panic(fmt.Sprintf("No error should happen when connecting to test database, but got err=%+v", er))
+	}
+	e:=db.Exec("create table if not exists example(name varchar, age integer)").Error
 	defer func(){
-		er := DB.Exec("drop table if exists example").Error
+		er := db.Exec("drop table if exists example").Error
 		if er != nil {
 			t.Fatal(e.Error())
 		}
@@ -1077,7 +1086,7 @@ func TestDB_CopyIn(t *testing.T) {
 	if e != nil {
 		t.Fatal(e.Error())
 	}
-	defer DB.Exec("drop table")
+	defer db.Exec("drop table")
 	var args = make([][]interface{}, 0)
 	args = append(args, []interface{}{
 		"tom", 9,
@@ -1086,7 +1095,7 @@ func TestDB_CopyIn(t *testing.T) {
 	}, []interface{}{
 		"jim", 11,
 	})
-	e = DB.CopyIn(true, "example", args, "name", "age")
+	e = db.CopyIn(true, "example", args, "name", "age")
 	if e != nil {
 		t.Fatal(e.Error())
 	}
@@ -1095,7 +1104,7 @@ func TestDB_CopyIn(t *testing.T) {
 		Age  int
 	}
 	var examples = make([]Example, 0)
-	e = DB.Raw("select * from example").Find(&examples).Error
+	e = db.Raw("select * from example").Find(&examples).Error
 	if e != nil {
 		t.Fatal(e.Error())
 	}