Pytest: Deselecting tests

With pytest, one can mark tests using a decorator

@pytest.mark.slow
def some_slow_test():
    pass

Then, from the command line, one can tell pytest to skip the tests marked "slow"

pytest -k-slow

If I have an additional tag:

@pytest.mark.long
def some_long_test()
    pass

I would like to be able to skip both long AND slow tests. I've tried this:

pytest -k-slow -k-long

and this:

pytest -k-slow,long

And neither seems to work.

At the command line, how do I tell pytest to skip both the slow AND the long tests?

Additionally, with the recent addition of the "-m" command line option you should be able to write:

py.test -m "not (slow or long)"

IOW, the "-m" option accepts an expression which can make use of markers as boolean values (if a marker does not exist on a test function it's value is False, if it exists, it is True).

Looking through the pytest code (mark.py) and further experimentation shows the following seems to work:

pytest -k "-slow -long"

(Using the --collect-only option speeds up experimentation)