pytest.skip() does not work with testing.condition

Test code:

import unittest                 
import pytest                   
from chainer.testing import condition                           

class TestAaa(unittest.TestCase):                               

    @condition.retry(32)        
    def test_aaa(self):         
        pytest.skip('aaa')      
        assert False            

Result:

________________________________________________________ TestAaa.test_aaa ________________________________________________________
chainer/testing/condition.py:74: in wrapper
    fail()
chainer/testing/condition.py:51: in fail
    instance.fail(msg)
E   AssertionError: 
E   Fail: 32, Success: 0
E   
E   The first error message:
E   Traceback (most recent call last):
E     File "/data/work/w/repos/chainer/chainer/testing/condition.py", line 60, in <lambda>
E       lambda: f(ins, *args[1:], **kwargs),
E     File "/data/work/w/repos/chainer/tests/chainer_tests/test_aaa.py", line 9, in test_aaa
E       pytest.skip('aaa')
E     File "/home/niboshi/anaconda/anaconda3/lib/python3.6/site-packages/_pytest/outcomes.py", line 72, in skip
E       raise Skipped(msg=msg)
E   Skipped: aaa
==================================================== 1 failed in 0.65 seconds ====================================================

After removing retry:

=================================================== 1 skipped in 0.60 seconds ====================================================

[kmaehashi]

Let’s fix chainer.testing to pass-through unittest.case.SkipTest exception, so that we can use the standard self.skipTest() until the discussion in #4557 has settled.

[niboshi]

It’s better to fix condition and allow pytest.skip(). https://github.com/cupy/cupy/pull/2483#discussion_r327523206