Flutter 联合测试颤振/飞镖未来误差的正确方法是什么？

我正在编写的单元测试应该在异常时失败，我希望使用匹配器匹配抛出的错误，但我得到了一个错误

我现在做错了什么？这里的错误是什么？ 如果我做得不正确，对于返回未来的方法，测试错误场景的正确方法是什么？为什么会有异步间隙

下面是我要测试的方法：

Future<void> registerUser(String name, String email, String password) async {
auth.signUp(email, password, name).then((_) {
      auth.getCurrentUser().then((user) async {
        // Doing something
    }).catchError((onError) {
      throw onError;
    });

我得到这个错误：

package:mockito/src/mock.dart 403:7               PostExpectation.thenThrow.<fn>
package:mockito/src/mock.dart 130:45              Mock.noSuchMethod
package:dive/repository/register_repo.dart 25:12  RegisterRepository.registerUser.<fn>
===== asynchronous gap ===========================
dart:async                                        Future.then
package:dive/repository/register_repo.dart 24:40  RegisterRepository.registerUser
test/repository/register_repo_test.dart 61:20     main.<fn>.<fn>

Closure: (dynamic) => Null

package:mockito/src/mock.dart 403:7 postExpection.thenthorn。
包：mockito/src/mock.dart 130:45 mock.noSuchMethod
包：dive/repository/register_repo.dart 25:12 RegisterRepository.registerUser。
======异步间隙===========================
dart:async Future.then
包：dive/repository/register_repo.dart 24:40 RegisterRepository.registerUser
测试/存储库/注册存储测试。dart 61:20主。。
闭包：（动态）=>Null

对于将来面临此问题的任何其他人

我从正在测试的方法中删除了async关键字，这里不需要async关键字。链接调用使其更具可读性：

---

测试现在通过。

感谢您演示如何捕获和测试Completer.completeError。我可以看到我的代码返回正确的东西，但我无法确定如何测试它。

package:mockito/src/mock.dart 403:7               PostExpectation.thenThrow.<fn>
package:mockito/src/mock.dart 130:45              Mock.noSuchMethod
package:dive/repository/register_repo.dart 25:12  RegisterRepository.registerUser.<fn>
===== asynchronous gap ===========================
dart:async                                        Future.then
package:dive/repository/register_repo.dart 24:40  RegisterRepository.registerUser
test/repository/register_repo_test.dart 61:20     main.<fn>.<fn>

Closure: (dynamic) => Null

Future<void> registerUser(String name, String email, String password) {
return auth
        .signUp(email, password, name)
        .then((_) => auth.getCurrentUser())
        .then((user) {
        // Doing something
    }).catchError((onError) {
      throw onError;
    });

test('should fail to register if fetching user fails', () async {
      MockAuth auth = MockAuth();
      RegisterRepository repo = RegisterRepository(auth);

      String password = 'password';
      String email = 'email';
      String name = 'name';

      when(auth.signUp(email, password, name))
          .thenAnswer((_) => Future.value());
      when(auth.getCurrentUser()).thenAnswer((_) => Future.error('error'));

      repo.registerUser(name, email, password).catchError((onError) {
        expect(onError.toString(), 'error');

        verify(auth.signUp(email, password, name)).called(1);
        verify(auth.getCurrentUser()).called(1);
        verifyNoMoreInteractions(auth);
      });
    });