How to report number of collected tests correctly after filter via pytest_collection_modifyitems

[mgaitan]

I'm developing a plugin to balance the execution of long suite among several instances that runs only a subset of the items. I was able to "filter" the tests, but the report is done before I mutate the items list, so it shows the original number of collected tests.

Suppose this

$ pytest --co tests/account/test_account.py 
==================================================================================== test session starts =====================================================================================
platform linux -- Python 3.6.8, pytest-6.2.1, py-1.8.1, pluggy-0.13.1 -- /usr/bin/python3
cachedir: .pytest_cache
rootdir: /src, configfile: pytest.ini
plugins: mock-3.5.0, typeguard-2.7.1, vcr-1.0.2, cov-2.6.1, freezegun-0.3.0.post1
collected 4 items                                                                                                                                                                            

<Package account>
  <Module test_account.py>
    <Function test_keys>
    <Function test_values>
    <Function test_account_new_feature_check>
    <Function test_account_get_warehouses_when_profile_is_not_defined>


================================================================================ 4 tests collected in 21.19s 

When I implement something like this

def pytest_collection_modifyitems(config, items):
    items[:]  = items[:len(items)//2]

I got

$ pytest --co tests/account/test_account.py 
==================================================================================== test session starts =====================================================================================
platform linux -- Python 3.6.8, pytest-6.2.1, py-1.8.1, pluggy-0.13.1 -- /usr/bin/python3
cachedir: .pytest_cache
rootdir: /src, configfile: pytest.ini
plugins: mock-3.5.0, typeguard-2.7.1, vcr-1.0.2, cov-2.6.1, freezegun-0.3.0.post1
collected 4 items                                                                                                                                                                            

<Package account>
  <Module test_account.py>
    <Function test_keys>
    <Function test_values>



================================================================================ 4 tests collected in 20.48s

How can I report correctly that "2 tests were collected" ?

[RonnyPfannschmidt]

The pytest_deselected hook has to be invoked atm

[mgaitan]

thanks!

[ws1088]

can you please elaborate the solution? thanks!