如何使用pytest测试异常和错误？

Question

I have functions in my Python code that raise exceptions in response to certain conditions, and would like to confirm that they behave as expected in my pytest scripts.

Currently I have

def test_something():
    try:
        my_func(good_args)
        assert True
    except MyError as e:
        assert False
    try:
        my_func(bad_args)
        assert False
    except MyError as e:
        assert e.message == "My expected message for bad args"

but this seems cumbersome (and needs to be repeated for each case).

Is there way to test exceptions and errors using Python, or a preferred pattern for doing so?

def test_something():
    with pytest.raises(TypeError) as e:
        my_func(bad_args)
        assert e.message == "My expected message for bad args"

does not work (ie it passes even if I replace the assertion with assert False ).

Answer 1

This way:

with pytest.raises(<YourException>) as exc_info:
    <your code that should raise YourException>

exception_raised = exc_info.value
<do asserts here>