Wrap each pytest test function into try-except

问题

I want to wrap each of my test functions into a try-except block to execute code in the except block. This code should only be executed if the test is failing.

I want to achieve this without altering the test functions, but instead use some kind of decorator/fixture. Unfortunately I can not find any examples.

Example of what I'm trying to achieve:

def test_1():
    some_method_that_might_throw_an_exception()

I have multiple tests and all of them should run a function run_only_if_exception_was_thrown() if an exception was thrown by the test. I want to achieve this without using a try/catch block inside the tests.

My current approach is to use sys.last_value inside a fixture to check if an exception was thrown:

@pytest.fixture
def fix():
    yield X()
    try:
        if sys.last_value:
            # error
    except AttributeError:
            # no error thrown

def test1(fix):
    some_method_that_might_throw_an_exception()

回答1:

How about this:

def test_dec(test_func):
    def test_wrapper(fix):
        try:
            test_func(fix)
        except:
            run_only_if_exception_was_thrown(fix)
            # re-raise exception to make the test fail
            raise

    return test_wrapper

Then in your test suite:

...
@test_dec
def test_one(fix):
    # test code

来源：https://stackoverflow.com/questions/43937748/wrap-each-pytest-test-function-into-try-except