`test` crashes on built-in functions

[mwermelinger]

The test function uses f.__code__.co_argcount to find out how many arguments f has, but built-in functions don't have the __code__ attribute and thus something like test(sorted, [...]) crashes. This is a minor limitation as we usually don't test built-in functions. The solution is to

• add to the documentation that built-in functions can't be tested

or

• find another way of determining the number of arguments, and preferably only the positional arguments

[densnow]

It looks like the inspect module could be a more robust way to do this, and more specifically inspect.signature. I'll just leave the link to the documentation here for now.

[mwermelinger]

Thanks, but the inspect documentation says that some CPython built-ins can't be handled either, so I'll just change the test docstring.