func findOne(coll *mongo.Collection, t *testing.T) { ss := &smallStruct{PER_TRIAL / 2} obj, err := mongo.Marshal(ss) if err != nil { t.Errorf("findOne Marshal: %v\n", err) } for i := 0; i < PER_TRIAL; i++ { _, err = coll.FindOne(obj) if err != nil { t.Errorf("findOne FindOne: %v\n", err) } } }