#19977 Pants swallowing PYTHONBREAKPOINT when attempting to use ipdb.set_trace Issue created by Jackevansevo Current Behaviour As demonstrated in the below example,

ipdb

is importable, and

PYTHONBREAKPOINT

is exported as

'ipdb.set_trace'

, yet

pdb

is still being used instead of

ipdb

.

def test_example():
    breakpoint()
    assert True

(3.11.4) ➜ pants test --debug test_example.py -- -s -q

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> PDB set_trace >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> /private/var/folders/yn/4q7r_wwd16v279lryh84bgtc0000gq/T/pants-sandbox-MQYs89/test_example.py(3)test_example()
-> assert True
(Pdb)

Expected Behaviour I should get an ipdb prompt. Currently this can only be achieved with:

python -m pytest

(3.11.4) ➜ PYTHONBREAKPOINT=ipdb.set_trace python -m pytest test_example.py -s -q
> /Users/jack/code/pants-ipdb-bug/test_example.py(3)test_example()
      1 def test_example():
      2     breakpoint()
----> 3     assert True

ipdb>

* * * Possible Cause After some discussion on slack: https://pantsbuild.slack.com/archives/C046T6T9U/p1696365035778499 It's believed this is because the

pytest

script is calling

python -sE

which wipes certain variables. After running

pants export ::

and activating the virtualenv this can be confirmed:

(3.11.4) ➜ head -1 $(which pytest)
#!/Users/jack/code/pants-ipdb-bug/dist/export/python/virtualenvs/python-default/3.11.4/bin/python3.11 -sE

Steps to reproduce I have the following environment:

BUILD

python_tests(
    name="root",
)

python_requirement(
    name="ipdb",
    requirements=["ipdb==0.13.13"],
)

python_requirement(
    name="pytest",
    requirements=["pytest==7.4.2"],
)

pants.toml

[GLOBAL]
pants_version = "2.17.0"
backend_packages = ["pants.backend.python"]

[python]
interpreter_constraints = ['==3.11.*']
enable_resolves = true

[python-infer]
use_rust_parser = true

[pytest]
install_from_resolve = "python-default"
requirements = [
  "//:pytest",
  "//:ipdb",
]

[test]
extra_env_vars = ["PYTHONBREAKPOINT=ipdb.set_trace"]

test_example.py

def test_example():
    breakpoint()
    assert True

Pants version 2.17.0 OS MacOS Additional info N/a pantsbuild/pants