Nosetest multi-process will run "TestCase" concurrently, but not smaller than that

Using --processes=4 which enables the multi-process testing mode for Noetest you might expect tests be run in fully concurrent, but here only each TestCase will be run that way, not a smaller unit than that.

import unittest
import os

'''
nosetest will run each class concurrently but each method sequentially
'''

class A(unittest.TestCase):

    def test_aa(self):
        import time
        time.sleep(1)
        self.assertEqual(0, os.getpid())

    def test_ab(self):
        import time
        time.sleep(1)
        self.assertEqual(0, os.getpid())

class B(unittest.TestCase):

    def test_ba(self):
        import time
        time.sleep(1)
        self.assertEqual(0, os.getpid())

    def test_bb(self):
        import time
        time.sleep(1)
        self.assertEqual(0, os.getpid())

class C(unittest.TestCase):

    def test_ca(self):
        import time
        time.sleep(1)
        self.assertEqual(0, os.getpid())

    def test_cb(self):
        import time
        time.sleep(1)
        self.assertEqual(0, os.getpid())