Missing stub error on Mockito in Flutter. Trying to use post of Dio

I think the problem was in the “FormData” instance in the prod function:

var formData = FormData.fromMap({
    'profileImage': await MultipartFile.fromFile(imagePath),
});

Every time the test runs, a new instance is created and the stub is not the same.

So the solution I found, is to use a type matcher to check if any parameter of type 'FormData' is called with the function.

 test('should verify if post method is successful called', () async {
    httpStubs.setUpMockHttpClientAppSuccess(expectedUrl, formData);

    await dataSource.setUserProfileImage(
      email: email,
      imagePath: imagePath,
    );

    verify(
      () => httpClientApp.post(
        expectedUrl,
        body: isA<FormData>(),
      ),
    ).called(1);
  });

The stub function:

void setUpMockHttpClientAppSuccess(String url, dynamic payload) {
when(
  () => httpClientApp.post(
    any(),
    body: any(named: 'body'),
  ),
).thenAnswer(
  (_) async => Response(
    data: null,
    statusCode: 200,
    requestOptions: CommomMocks.getRequestOptions(url),
  ),
);

}

I'm not sure if the solution is the best or the best practice, therefore this resolves my test problem. If someone knows a better solution, please tell me.

Thanks to all!! :)