PYTHON setup.py build_ext --inplace
PYTHON -c "import a"

######## setup.py ########

from Cython.Build.Dependencies import cythonize
from distutils.core import setup

setup(
    ext_modules = cythonize("**/*.pyx"),
    )

######## a.pyx ########

import sys
import a
assert a in sys.modules.values(), list(sys.modules)
assert sys.modules['a'] is a, list(sys.modules)

from atest.package import module

######## atest/__init__.py ########

######## atest/package/__init__.py ########

######## atest/package/module.pyx ########

import sys
assert 'atest.package.module' in sys.modules

import a
import atest.package.module as module
assert module in sys.modules.values(), list(sys.modules)
assert sys.modules['atest.package.module'] is module, list(sys.modules)