python - 如何测试在对象实例化期间创建的函数？

Question

我正在尝试编写测试以确保我的程序在给定特定输入的情况下生成特定输出。我已经成功地模拟了我想要测试的输入，但是我一直无法模拟输出函数。我对我尝试过的事情和他们的错误留下了一些评论。我怎样才能使这些测试起作用？

这是我的测试:

from src_dir import my_class

    class Mock_Dependency:
        def __init__( self ):
            pass
        def print_stuff( self, stuff ):
            ##return MagicMock() - does not have attribute called
            return stuff

    @fixture
    @patch('src_dir.dependency.Dependency, Mock_Dependency)
    def subject():
        return my_class.My_Class()

    ##@patch('subject.print_stuff', MagicMock) - No module named subject
    ##@patch('my_class.My_Class.print_stuff', MagicMock) - does not have attribute print stuff
    def test_print_stuff_was_called( subject ):
        assert subject.print_stuff.called
    def test_print_stuff_printed( subject ):
        assert subject.print_stuff == 'a word'

这是我的课:

from dependency import Dependency

class My_Class:
  def __init__( self ):
    self.print_stuff = Dependency.print_stuff()
  def run( self ):
    self.print_stuff('a word')

Answer 1

我的问题的解决方案是在收到夹具 subject 后在测试函数中模拟 print_stuff :

def test_print_stuff_was_called( subject ):
    with patch.object(subject, 'print_stuff') as mock:
        subject.run()
    mock.assert_called_with('a word') # pass
    mock.assert_called_with('anything else') # fail