'Test `tee` from a pipe to a pipe'

def test_tee_pipe_to_pipe(self):

    with pipe() as (p1a, p1b):
        with pipe() as (p2a, p2b):
            os.write(p1b, 'abcdef')
            res = tee(p1a, p2b, 3, 0)
            self.assertEqual(res, 3)
            self.assertEqual(os.read(p2a, 3), 'abc')
            self.assertEqual(os.read(p1a, 6), 'abcdef')
