渡槽：错误状态：找不到“_MyEntity”的实体。您是否忘记创建 'ManagedContext'？

Question

我正在开始一个新项目并希望使用测试驱动 development.This 是我的实体：

import 'package:aqueduct/aqueduct.dart';

class MyEntity extends ManagedObject<_MyEntity> implements _MyEntity {}class _MyEntity {
  @primaryKey
  int id;
  int myValue;
}

我想在从文本文件中提取一些数据时独立于数据库使用 MyEntity。但是当我尝试像这样测试它时

void main() {
  test('DatabaseBuilder returns multiple entities', () {
    List<MyEntity> entities = [];
    entities.add(MyEntity());
    expect(entities.length, greaterThan(0));
  });
}

我收到以下错误：

Bad state: No entity found for '_MyEntity. Did you forget to create a 'ManagedContext'?

是否不允许我将实体用于非数据库逻辑？

Answer 1

This question was answered on the Aqueduct Slack channel 所以我把它移到这里是为了更容易搜索。

Reductions answered:

You will need to start a TestHarness with TestHarnessORMMixin mixed in. After that you can used the MnagedObject (sic) however you find fit.

joeconwaystk followed up:

Yes, what Reductions said… the framework handles TDD with the ORM by creating a temporary schema in your database server during testing (with the TestHarnessORMixin)

所以我将 test/harness/app.dart 文件更新为如下所示：

class Harness extends TestHarness<MyChannel> with TestHarnessORMMixin {
  @override
  Future onSetUp() async {
    await resetData();
  }

  @override
  Future onTearDown() async {}

  @override
  ManagedContext get context => channel.context;
}

我的测试看起来像这样：

Future main() async {
  final harness = Harness()..install();

  test('DatabaseBuilder returns multiple entities', () {
    List<MyEntity> entities = [];
    entities.add(MyEntity());
    expect(entities.length, greaterThan(0));
  });
}

即使我没有直接使用线束，安装它也足以消除错误。

如果您不喜欢这种方法，我发现的另一个选择是创建一个模型 class 来镜像 _MyEntity 而不扩展 ManagedObject:

class MyEntityModel implements _MyEntity {
  @override
  int id;

  @override
  int myValue;
}

这可以在实际插入数据库时映射到 MyEntity。只安装测试工具并直接使用 MyEntity 似乎更好，所以我就是这样做的。

有关设置测试的更多帮助，请参阅 this video and the documentation。

Answer 2

对我来说，实例化一个 ManagedContext:

就足够了

void main() {
  final dataModel = ManagedDataModel.fromCurrentMirrorSystem();
  final _ = ManagedContext(dataModel, null);

  // my tests go here
}

我做一个简单的单元测试，不需要数据库。

渡槽：错误状态：找不到“_MyEntity”的实体。您是否忘记创建 'ManagedContext'？

Aqueduct: Bad state: No entity found for '_MyEntity'. Did you forget to create a 'ManagedContext'?

database

tdd

dart

server

aqueduct