pytest：未引发上下文管理器内的 AssertionError

Question

还有一些类似的问题，例如Pytests with context manager. Still I don't get it. Why is this assertion inside a context manager没有提出来？

class foo:
    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        return self

def test_context_manager():
    with foo():
        assert False  # <- works outside the with statement but not here

使用：python3.9 和 pytest6.2.5

更新： 当上下文管理器的 __exit__ 方法不是 return 时它起作用。这有效：

class foo:
    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        pass  # <- this fixes it

但问题依然存在。为什么第一种情况会失败。这是一个错误吗？我要举报吗？

Answer 1

上下文管理器旨在捕获此类异常并将其传递给 __exit__。如果要抛出异常，需要自己处理：

class foo:
    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        if exc_value:
            raise exc_value # AssertionError raised here
        return self

def test_context_manager():
    with foo():
        assert False

test_context_manager()

pytest：未引发上下文管理器内的 AssertionError

pytest: AssertionError inside Context Manager not raised

python

contextmanager

pytest

python-3.x