self.skipTest does not produce the same results as unittest does

Given this test case:

from unittest import TestCase, main

class T(TestCase):

    def test_foo(self):
        for i in range(5):
            with self.subTest(msg="custom", i=i):
                if i % 2 == 0:
                    self.skipTest('even number')


if __name__ == '__main__':
    main()

Running with python:

λ python .tmp\test-ut-skip.py
sss
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK (skipped=3)

Running with pytest:

 λ pytest .tmp\test-ut-skip.py -q
ss                                                             [100%]
2 skipped in 0.01 seconds

The problem is that TestCaseFunction.addSkip will append the exception info to a list, but pytest_runtest_makereport will only pop one item off the list. We need to find a way to hook into TestCase.subTest to issue pytest_runtest_logreport from within the with statement.

Start by reproducing the example with both unittest and pytest, then inspect TestCaseFunction.addSkip and pytest_runtest_makereport. Trace how each self.subTest skip is recorded and reported; done means pytest reports all three skipped subtests, matching unittest's result.