pytest fails due to ModuleNotFoundError, but works when using "python -m pytest"

Similarly to this OP's issue, but the other way around, pytest works for me within my virtual environment ("venv") only when running python -m pytest, but not with just running pytest in my console.

I'm working with VS Code on Windows 10 within the built-in console.

The command pytest does not work in neither scenario: neither in the global scope, nor in the target venv. By contrast, python -m pytest works within said venv.

I'm working with CLI from the root directory of the project whose full directory tree is:

(Testing) PS C:\Users\user\Documents\Programming\Testing> tree /F
Folder PATH listing for volume Windows
Volume serial number is 50BE-501E
C:.
│   default_python_script.py
│
├───.benchmarks
├───.pytest_cache
│   │   .gitignore
│   │   CACHEDIR.TAG
│   │   README.md
│   │
│   └───v
│       └───cache
│               lastfailed
│               nodeids
│               stepwise
│
├───.vscode
│       launch.json
│       settings.json
│
├───cli_testapp
│   │   cli_testapp.py
│   │   __init__.py
│   │
│   └───__pycache__
│           cli_testapp.cpython-39.pyc
│           __init__.cpython-39.pyc
│
├───my_sum
│   │   my_sum.py
│   │   __init__.py
│   │
│   └───__pycache__
│           my_sum.cpython-39.pyc
│           __init__.cpython-39.pyc
│
├───tests
│   │   errors_pytest.log
│   │   test.py
│   │   testing.py
│   │   test_with_pytest.py
│   │
│   ├───.benchmarks
│   ├───.pytest_cache
│   │   │   .gitignore
│   │   │   CACHEDIR.TAG
│   │   │   README.md
│   │   │
│   │   └───v
│   │       └───cache
│   │               lastfailed
│   │               nodeids
│   │               stepwise
│   │
│   └───__pycache__
│           test.cpython-39.pyc
│           testing.cpython-39.pyc
│           test_with_pytest.cpython-39-pytest-6.2.3.pyc
│           test_with_pytest.cpython-39.pyc
│
└───__pycache__
        test.cpython-39.pyc
        testing.cpython-39.pyc

What's annoying about it is that I'd like to use the helpful VS Code testing kit, which facilitates employing any testing framework, also pytest. The problem is that VS Code uses the following command by default to run the testing:

python c:\Users\user\.vscode\extensions\ms-python.python-2021.3.680753044\pythonFiles\testing_tools\run_adapter.py discover pytest -- --rootdir c:\Users\user\Documents\Programming\Testing -s tests

As one can inspect, it uses pytest instead of python -m pytest. Apparently, the default way of implementation via VS Code doesn't load correctly the environmental variables, since it always produces the following error:

Test Discovery failed:
Error: ============================= test session starts =============================
platform win32 -- Python 3.9.0a4, pytest-6.2.3, py-1.10.0, pluggy-0.13.1
benchmark: 3.4.1 (defaults: timer=time.perf_counter disable_gc=False min_rounds=5 min_time=0.000005 max_time=1.0 calibration_precision=10 warmup=False warmup_iterations=100000)
rootdir: c:\Users\user\Documents\Programming\Testing
plugins: benchmark-3.4.1
collected 0 items / 1 error

=================================== ERRORS ====================================
_________________ ERROR collecting tests/test_with_pytest.py __________________
ImportError while importing test module 'c:\Users\user\Documents\Programming\Testing\tests\test_with_pytest.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
..\..\..\.pyenv\pyenv-win\versions\3.9.0a4\lib\importlib\__init__.py:127: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
tests\test_with_pytest.py:22: in <module>
    from cli_testapp import cli_testapp
E   ModuleNotFoundError: No module named 'cli_testapp'
=========================== short test summary info ===========================
ERROR tests/test_with_pytest.py
!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!
==================== no tests collected, 1 error in 0.23s =====================

Traceback (most recent call last):
  File "c:\Users\user\.vscode\extensions\ms-python.python-2021.3.680753044\pythonFiles\testing_tools\run_adapter.py", line 22, in <module>
    main(tool, cmd, subargs, toolargs)
  File "c:\Users\user\.vscode\extensions\ms-python.python-2021.3.680753044\pythonFiles\testing_tools\adapter\__main__.py", line 100, in main
    parents, result = run(toolargs, **subargs)
  File "c:\Users\user\.vscode\extensions\ms-python.python-2021.3.680753044\pythonFiles\testing_tools\adapter\pytest\_discovery.py", line 44, in discover
    raise Exception("pytest discovery failed (exit code {})".format(ec))
Exception: pytest discovery failed (exit code 2)

For the sake of completeness, I'm going to post how it looks like with python -m pytest within the venv correctly loaded (CLI utilized here):

(Testing) PS C:\Users\user\Documents\Programming\Testing> python -m pytest
=================================================================== test session starts ===================================================================
platform win32 -- Python 3.9.0a4, pytest-6.2.3, py-1.10.0, pluggy-0.13.1
benchmark: 3.4.1 (defaults: timer=time.perf_counter disable_gc=False min_rounds=5 min_time=0.000005 max_time=1.0 calibration_precision=10 warmup=False warmup_iterations=100000)
rootdir: C:\Users\user\Documents\Programming\Testing
plugins: benchmark-3.4.1
collected 7 items

tests\test_with_pytest.py .F....F                                                                                                                    [100%]

======================================================================== FAILURES =========================================================================
____________________________________________________________________ test_always_fails ____________________________________________________________________

    def test_always_fails():
        """Function docs:\n
        See above with function docs of "test_always_passes()".
        """
>       assert False
E       assert False

tests\test_with_pytest.py:46: AssertionError
______________________________________________________________ test_initial_transform[dict] _______________________________________________________________

generate_initial_transform_parameters = ({'city': 'Anytown', 'name': ...})

    def test_initial_transform(generate_initial_transform_parameters):
        test_input = generate_initial_transform_parameters[0]
        expected_output = generate_initial_transform_parameters[1]
>       assert cli_testapp.initial_transform(test_input) == expected_output
E       AssertionError: assert {'city': 'Any...e': 'FL', ...} == {'city': 'Any...Public'], ...}
E         Omitting 5 identical items, use -vv to show
...

tests\test_with_pytest.py:118: AssertionError
================================================================= short test summary info =================================================================
FAILED tests/test_with_pytest.py::test_always_fails - assert False
FAILED tests/test_with_pytest.py::test_initial_transform[dict] - AssertionError: assert {'city': 'Any...e': 'FL', ...} == {'city': 'Any...Public'], ...}
=============================================================== 2 failed, 5 passed in 0.31s ===============================================================

How can I resolve this issue that it'll always work, also with just pytest? This is particularly important, because I'd love to leverage the amenities provided by VS Code, which employs a default command based on just pytest.