t.Fatalf("no error should happen but got %v", err)
	}
}

func TestPreparedStmtFromTransaction(t *testing.T) {
	db := DB.Session(&gorm.Session{PrepareStmt: true, SkipDefaultTransaction: true})

	tx := db.Begin()
	defer func() {
		if r := recover(); r != nil {
			tx.Rollback()
		}
	}()
	if err := tx.Error; err != nil {
		t.Errorf("Failed to start transaction, got error %v\n", err)
	}

		}
	}()

	db, err := gorm.Open(mysql.New(mysql.Config{Conn: conn, DisableWithReturning: true}))
	if err != nil {
		t.Fatalf("Should open db success, but got %v", err)
	}

	tx := db.Begin()
	user := *GetUser("transaction", Config{})

	if err = tx.Save(&user).Error; err != nil {
		t.Fatalf("No error should raise, but got %v", err)
	}

	db.Mux.Unlock()

	// prepare completed
	defer close(cacheStmt.prepared)

	// Reason why cannot lock conn.PrepareContext
	// suppose the maxopen is 1, g1 is creating record and g2 is querying record.
	// 1. g1 begin tx, g1 is requeue because of waiting for the system call, now `db.ConnPool` db.numOpen == 1.
	// 2. g2 select lock `conn.PrepareContext(ctx, query)`, now db.numOpen == db.maxOpen , wait for release.