pytest - mockup a complex module import - pytest

Question

I have found several posts on how to "hide" a package and simulate an ImportError with pytest, however, I haven't succeeded in my case and I am looking for some help:
Test for import of optional dependencies in __init__.py with pytest: Python 3.5 /3.6 differs in behaviour
Test behavior of code if optional module is not installed
and related
Here is the content of an __about__.py file that I want to test with pytest.
"""Get the metadata from the package or from setup.py."""
try:
import importlib
metadata = importlib.metadata
except ImportError:
import importlib_metadata as metadata
try:
data = metadata.metadata("mypackage")
__version__ = data["Version"]
__author__ = data["Author"]
__name__ = data["Name"]
except metadata.PackageNotFoundError:
# The repo of the package is accessible to python to get at least the version
import re
from pathlib import Path
try:
from nested_grid_plotter import __file__ as loc
with open(Path(loc).parent.joinpath("../setup.py"), "r") as f:
data = f.read()
except FileNotFoundError:
data = ""
def version_parser(v):
"""Parse the version from the setup file."""
version_pattern = (
r"""(version\s*=\s*)["|'](\d+(=?\.(\d+(=?\.(\d+)*)*)*)*)["|']"""
)
regex_matcher = re.compile(version_pattern).search(v)
if regex_matcher is None:
return "unknwon"
return regex_matcher.group(2)
try:
__version__ = version_parser(data)
except Exception:
__version__ = "unknown"
__author__ = "unknown"
__name__ = "unknown"
Here is the __init__.py at the root of the package:
from .__about__ import __version__, __name__, __author__
And here is the tests that I have come up with until now. However, I am not able to hide importlib.
"""Test the file __about__.py."""
import pytest
import sys
class PackageDiscarder:
def __init__(self):
self.pkgnames = []
def find_spec(self, fullname, path, target=None):
if fullname in self.pkgnames:
raise ImportError()
#pytest.fixture
def no_requests():
sys.modules.pop("importlib", None)
d = PackageDiscarder()
d.pkgnames.append("importlib")
sys.meta_path.insert(0, d)
yield
sys.meta_path.remove(d)
#pytest.fixture(autouse=True)
def cleanup_imports():
yield
sys.modules.pop("mypackage", None)
def test_requests_available():
import mypackage
assert mypackage.__version__ != "unknwon"
#pytest.mark.usefixtures("no_requests")
def test_requests_missing():
import mypackage
assert mypackage.__version__ != "unknwon"
Here is the coverage report:
Name Stmts Miss Cover Missing
----------------------------------------------------------------
mypackage/__about__.py 31 10 68% 5-6, 10-12, 23-24, 33, 38-39
----------------------------------------------------------------
TOTAL 31 10 68%