Python subTest usage and how py.test is not able to report subTest failures.

py.test.txt

$ py.test test.py 
=============================================== test session starts ===============================================
platform linux -- Python 3.5.2, pytest-3.0.5, py-1.4.31, pluggy-0.4.0
rootdir: /home/elyezer/code, inifile: 
collected 1 items 

test.py F

==================================================== FAILURES =====================================================
_______________________________________ TestIsEven.test_should_all_be_even ________________________________________

self = <test.TestIsEven testMethod=test_should_all_be_even>

    def test_should_all_be_even(self):
        for n in (0, 4, -2, 3, 7, 11):
            with self.subTest(n=n):
>               self.assertTrue(is_even(n))
E               AssertionError: False is not true

test.py:12: AssertionError
============================================ 1 failed in 0.04 seconds =============================================

test.py

from unittest import TestCase


def is_even(n):
        return n % 2 == 0


class TestIsEven(TestCase):
    def test_should_all_be_even(self):
        for n in (0, 4, -2, 3, 7, 11):
            with self.subTest(n=n):
                self.assertTrue(is_even(n))

unittest.txt

$ python3 -m unittest test.py

======================================================================
FAIL: test_should_all_be_even (test.TestIsEven) (n=3)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/elyezer/code/pulp-smash/test.py", line 12, in test_should_all_be_even
    self.assertTrue(is_even(n))
AssertionError: False is not true

======================================================================
FAIL: test_should_all_be_even (test.TestIsEven) (n=7)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/elyezer/code/pulp-smash/test.py", line 12, in test_should_all_be_even
    self.assertTrue(is_even(n))
AssertionError: False is not true

======================================================================
FAIL: test_should_all_be_even (test.TestIsEven) (n=11)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/elyezer/code/pulp-smash/test.py", line 12, in test_should_all_be_even
    self.assertTrue(is_even(n))
AssertionError: False is not true

----------------------------------------------------------------------
Ran 1 test in 0.001s

FAILED (failures=3)