Can't find lib with modulefinder if there is importlib.import_module

Question

My task is to write a function that takes the name of the file and analyzes it and outputs all the non-standard libraries that it uses. And I can't use non-standard libraries to write a script.Example:

import sys
from modulefinder import ModuleFinder

finder = ModuleFinder(['file_test_me.py'])
finder.run_script('file_test_me.py')

result = set(finder.badmodules.keys())
exclude = result - sys.modules.keys()

print(exclude)

file_test_me.py:

import os
import pytest

from numpy import matrix

def something():
    import math
    import scipy
    import pandas as pd
    import importlib
    module = importlib.import_module('sklearn')
    dir(module)

The result I want to get from 1 script is: {'scipy', 'numpy', 'pandas', 'pytest', 'sklearn'}, but I don't get sklearn in this list.