Question

我是Python新手，所以如果这是一个重复或过于简单的问题，我会道歉。我编写了一个协调器类，调用另外两个使用kafka-python库来发送/读取Kafka数据的类。我想为我的协调员课程编写一个单元测试，但是我很难弄清楚如何最好地解决这个问题。我希望我可以创建一个替代构造函数，我可以将我的模拟对象传递给它，但是这似乎不起作用，因为我得到一个错误，即test_mycoordinator无法解析。我是否会以错误的方式测试这门课程？我应该测试一种pythonic方式吗？

这是我的测试类到目前为止的样子：

import unittest
from mock import Mock
from mypackage import mycoordinator

class MyTest(unittest.TestCase):

    def setUpModule(self):
        # Create a mock producer
        producer_attributes = ['__init__', 'run', 'stop']
        mock_producer = Mock(name='Producer', spec=producer_attributes)

        # Create a mock consumer
        consumer_attributes = ['__init__', 'run', 'stop']
        data_out = [{u'dataObjectID': u'test1'},
                    {u'dataObjectID': u'test2'},
                    {u'dataObjectID': u'test3'}]
        mock_consumer = Mock(
            name='Consumer', spec=consumer_attributes, return_value=data_out)

        self.coor = mycoordinator.test_mycoordinator(mock_producer, mock_consumer)

    def test_send_data(self):
        # Create some data and send it to the producer
        count = 0
        while count < 3:
            count += 1
            testName = 'test' + str(count)
            self.coor.sendData(testName , None)

以下是我要测试的课程：

class MyCoordinator():
    def __init__(self):
        # Process Command Line Arguments using argparse  
        ...

        # Initialize the producer and the consumer
        self.myproducer = producer.Producer(self.servers,
                                            self.producer_topic_name)

        self.myconsumer = consumer.Consumer(self.servers,
                                            self.consumer_topic_name)

    # Constructor used for testing -- DOES NOT WORK
    @classmethod
    def test_mycoordinator(cls, mock_producer, mock_consumer):
        cls.myproducer = mock_producer
        cls.myconsumer = mock_consumer

    # Send the data to the producer
    def sendData(self, data, key):
        self.myproducer.run(data, key)

    # Receive data from the consumer
    def getData(self):
        data = self.myconsumer.run()
        return data

Answer 1

无需提供单独的构造函数。模拟修补代码以用模拟替换对象。只需在测试方法上使用mock.patch() decorator;它将传递对生成的模拟对象的引用。

在创建实例之前， producer.Producer()和consumer.Consumer()都会被模拟出：

import mock class MyTest(unittest.TestCase): @mock.patch('producer.Producer', autospec=True) @mock.patch('consumer.Consumer', autospec=True) def test_send_data(self, mock_consumer, mock_producer): # configure the consumer instance run method consumer_instance = mock_consumer.return_value consumer_instance.run.return_value = [ {u'dataObjectID': u'test1'}, {u'dataObjectID': u'test2'}, {u'dataObjectID': u'test3'}] coor = MyCoordinator() # Create some data and send it to the producer for count in range(3): coor.sendData('test{}'.format(count) , None) # Now verify that the mocks have been called correctly mock_producer.assert_has_calls([ mock.Call('test1', None), mock.Call('test2', None), mock.Call('test3', None)])

因此，在调用test_send_data时，mock.patch()代码将模拟对象替换为producer.Producer引用。然后，您的MyCoordinator类使用这些模拟对象而不是真实代码。调用producer.Producer()返回一个新的模拟对象（mock_producer.return_value引用的同一对象）等。

我假设producer和consumer是顶级模块名称。如果不是，请提供完整的导入路径。来自mock.patch()文档：

target 应为'package.module.ClassName'形式的字符串。导入目标并将指定的对象替换为新对象，因此目标必须可从您正在调用的环境中导入patch()。执行修饰函数时导入目标，而不是在装饰时导入。

我如何模拟部分python构造函数进行测试？

1 个答案: