如何在测试中伪造Popen?

时间:2019-05-08 14:32:20

标签: python pytest popen

我已经使用自己的Fake实现成功地伪造了其他模块 monkeypatch。但是在这种情况下,同时使用伪造实现或Monkeypatch 因subprocess.Popen而失败:

  • 使用monkeypatch失败。结果还是真实的打开 Windows标题,而不是“ foo”。
class TestController:

    def test_get_all_windows(self, ctrl_fixture, monkeypatch):

        def fake_communicate(a):
            return "foo"

        monkeypatch.setattr(subprocess.Popen, 'communicate', fake_communicate)
        output = ctrl_fixture.get_all_windows()
        print(output)

  • 使用伪造也失败了,我试图模仿original,但 它仍然失败。 output的结果仍然是真实的窗口 标题,而不是“ foo”
class FakePopen(object):
    def __init__(self, args, stdout=None):
        super().__init__()      
        self.args = args
        self.stdout = stdout

    def communicate(self):
        return "foo"

class TestController:
    def test_get_all_windows(self, ctrl_fixture, monkeypatch, mocker):

        def fake_communicate(a):
            return "foo"
        subprocess.Popen = FakePopen
        subprocess.Popen.communicate = fake_communicate
        output = ctrl_fixture.get_all_windows()
        print(output)

我的功能是:

    def get_all_windows(self):
        all_windows = ""
        all_windows_proc = Popen(["wmctrl", "-l"], stdout=PIPE)
        all_windows_dirty, err = all_windows_proc.communicate()
        for line in all_windows_dirty.splitlines():
            windows_name = line.split(None, 3)[-1].decode()
            all_windows += "{}\n".format(windows_name)
        return all_windows

上面使用print而不是assert的测试导致我仍然要检查输出。

谢谢。

更新解决方案

根据munk条评论。非常感谢他。

两种解决方案均有效:

def test_get_all_windows_one(self, ctrl, monkeypatch):

    window_title = b"0x006000ab  0 machine-name foo_window_title"

    def fake_communicate(a):
        return window_title, "err"

    Lupr.controllers.controller.Popen = FakePopen
    Lupr.controllers.controller.Popen.communicate = fake_communicate

    output = ctrl.get_all_windows()
    assert output == "foo_window_title\n"

def test_get_all_windows_two(self, ctrl, monkeypatch):

    window_title = b"0x006000ab  0 machine-name foo_window_title"

    def fake_communicate(a):
        return window_title, "err"

    monkeypatch.setattr(Lupr.controllers.controller, "Popen", FakePopen)
    monkeypatch.setattr(
        Lupr.controllers.controller.Popen, "communicate", fake_communicate
    )
    output = ctrl.get_all_windows()
    assert output == "foo_window_title\n"

1 个答案:

答案 0 :(得分:0)

您正在修补subprocess.Popen,但是在测试功能中,您正在直接使用Popen。您正在更改错误的符号表。

如果您的函数位于foo.py中,则您想修补foo.Popen或将其功能更改为使用subprocess.Popen