on pypy, skip test that depends on gc behaviour

[mattip]

The test added in #5510 does not pass on PyPy. Without adding a gc.collect, the releaseis never called. But even when addinggc.collect() between the deletions, the output is different. With this change:

from cython.parallel cimport prange
 cimport cython
+import gc
 from random import randint, random
 
 include "../buffers/mockbuffers.pxi"
@@ -43,8 +44,11 @@ def refcounting_stress_test(int N):
 
     # make "release" order predictable
     del aview
+    gc.collect()
     del bview
+    gc.collect()
     del cview
+    gc.collect()
 
     return total

I get as output (release c comes before release b)

    acquired a
    acquired b
    acquired c
    released a
    released c
    released b

I don't think there is a way to get doctest to have alternatives based on implementation, so I suggest skipping the test.

[da-woods]

Thanks @mattip

I don't think there is a way to get doctest to have alternatives based on implementation,

What you can do is put in on the global or class docstring (since these are editable easily) rather than a function docstring:

if pypy:
  __doc__ += """
    >>> something
   """
else:
  __doc__ += """
    >>> something_else
    """

I think in this case skipping is the way to go though.

The other option would be to use Doctest.ELLIPSIS - we care that there's three releases, but we don't really care about the order, so we could rephrase the test to just look for that.

[mattip]

Thanks. Maybe at some point git blame will bring someone who is trying to unskip PyPy tests to your comment.