模拟补丁方法和一个属性

我想修补一个方法返回的数据的一个属性。

假设我有以下简化的工件代码:

@patch('requests.post')
class TestKeywordsApi(BaseTest):
    # Instantiate API class and set the apikey
    def setUp(self):
        BaseTest.setUp(self)
        self.fixtures = FIXTURES
        self.api = BaseApi()

    def mock_requests_post(self, url, data=None):
        ''' Mock method for post method from responses library.
            It replaces the responses.post calls in Api class.
        '''
        url = self.encode_url(url, data)
        if url:
            return self.fixtures[url]

    def test_save_success(self, mock_post):
        mock_post.side_effect = self.mock_requests_post

        response = self.api.post(keyword, params={...})

        # list of asserts

# original class calling requests.post    
import requests
class BaseApi(object):
    def post(self, action, params):
        ''' Sends a POST request to API '''
        response = requests.post(self.build_url(action), data=params).content

上面的代码失败了,因为mock方法没有为请求库中存在的“content”属性提供mock/stub。有人知道如何截断内容属性吗?