如何對 Flutter 中依賴於 3rd-Party-Package 的代碼進行單元測試？

Question

如何測試 flutter 中的代碼，這取決於 path_provider 插件？

對依賴於 path_provider 插件的代碼執行測試時，出現以下錯誤：

  MissingPluginException(No implementation found for method getStorageDirectory on channel plugins.flutter.io/path_provider)
  package:flutter/src/services/platform_channel.dart 319:7                         MethodChannel.invokeMethod
  ===== asynchronous gap ===========================
  dart:async                                                                       _asyncErrorWrapperHelper
  package: mypackage someClass.save
  unit_tests/converter_test.dart 19:22   

                                 main.<fn>

Answer 1

您需要模擬被測試代碼調用的所有方法（如果它調用它們並取決於它們的結果）

在您的情況下，您應該模擬方法getStorageDirectory()以使其返回一些滿足您的測試的結果

有關如何模擬檢查這個和這個的更多信息

如何模擬的一個簡短示例：

class MyRepo{
  int myMethod(){
    return 0;
  }
}

class MockRepo extends Mock implements MyRepo{}

void main(){
  MockRepo mockRepo = MockRepo();
  test('should test some behaviour',
          () async {
            // arrange
            when(mockRepo.myMethod()).thenAnswer(1);//in the test when myMethod is called it will return 1 and not 0
            // act
            //here put some method that will invoke myMethod on the MockRepo and not on the real repo
            // assert
            verify(mockRepo.myMethod());//verify that myMethod was called
          },
        );
}