Python 3.12.0b1/2 Missing Coverage for Exiting a Conditional in a Finally Block

[rmartin16]

Describe the bug
Covered branch for exiting from a conditional in a finally block is being reported uncovered in Python 3.12.0 beta 1 and beta 2.

To Reproduce
How can we reproduce the problem? Please be specific. Don't link to a failing CI job. Answer the questions below:

1. What version of Python are you using?

• 3.12.0b1 and 3.12.0b2

2. What version of coverage.py shows the problem? The output of coverage debug sys is helpful.

• All of my testing was with coverage==7.2.7 but this problem also occurs for master.

coverage debug sys

~/github/beeware via 🐍 v3.12.0b2+ (venv-3.12-briefcase) took 2s 
❯ coverage debug sys
-- sys -------------------------------------------------------
               coverage_version: 7.2.7
                coverage_module: /home/russell/github/beeware/briefcase/venv-3.12-briefcase/lib/python3.12/site-packages/coverage/__init__.py
                         tracer: -none-
                        CTracer: available
           plugins.file_tracers: -none-
            plugins.configurers: -none-
      plugins.context_switchers: -none-
              configs_attempted: .coveragerc
                                 setup.cfg
                                 tox.ini
                                 pyproject.toml
                   configs_read: -none-
                    config_file: None
                config_contents: -none-
                      data_file: -none-
                         python: 3.12.0b2+ (heads/3.12:8c4cf96a06, Jun 10 2023, 14:09:05) [GCC 11.3.0]
                       platform: Linux-6.2.6-76060206-generic-x86_64-with-glibc2.35
                 implementation: CPython
                     executable: /home/russell/github/beeware/briefcase/venv-3.12-briefcase/bin/python
                   def_encoding: utf-8
                    fs_encoding: utf-8
                            pid: 1331663
                            cwd: /home/russell/github/beeware
                           path: /home/russell/github/beeware/briefcase/venv-3.12-briefcase/bin
                                 /home/russell/.pyenv/versions/3.12-dev/lib/python312.zip
                                 /home/russell/.pyenv/versions/3.12-dev/lib/python3.12
                                 /home/russell/.pyenv/versions/3.12-dev/lib/python3.12/lib-dynload
                                 /home/russell/github/beeware/briefcase/venv-3.12-briefcase/lib/python3.12/site-packages
                                 /home/russell/github/beeware/briefcase/src
                    environment: CONDA_PYTHON_EXE = /home/russell/anaconda3/bin/python
                                 HOME = /home/russell
                                 PYENV_ROOT = /home/russell/.pyenv
                                 PYENV_SHELL = bash
                                 PYENV_VIRTUALENV_INIT = 1
                                 PYTHONDEVMODE = 1
                   command_line: /home/russell/github/beeware/briefcase/venv-3.12-briefcase/bin/coverage debug sys
         sqlite3_sqlite_version: 3.37.2
             sqlite3_temp_store: 0
        sqlite3_compile_options: ATOMIC_INTRINSICS=1, COMPILER=gcc-11.3.0, DEFAULT_AUTOVACUUM,
                                 DEFAULT_CACHE_SIZE=-2000, DEFAULT_FILE_FORMAT=4,
                                 DEFAULT_JOURNAL_SIZE_LIMIT=-1, DEFAULT_MMAP_SIZE=0, DEFAULT_PAGE_SIZE=4096,
                                 DEFAULT_PCACHE_INITSZ=20, DEFAULT_RECURSIVE_TRIGGERS,
                                 DEFAULT_SECTOR_SIZE=4096, DEFAULT_SYNCHRONOUS=2,
                                 DEFAULT_WAL_AUTOCHECKPOINT=1000, DEFAULT_WAL_SYNCHRONOUS=2,
                                 DEFAULT_WORKER_THREADS=0, ENABLE_COLUMN_METADATA, ENABLE_DBSTAT_VTAB,
                                 ENABLE_FTS3, ENABLE_FTS3_PARENTHESIS, ENABLE_FTS3_TOKENIZER, ENABLE_FTS4,
                                 ENABLE_FTS5, ENABLE_JSON1, ENABLE_LOAD_EXTENSION, ENABLE_MATH_FUNCTIONS,
                                 ENABLE_PREUPDATE_HOOK, ENABLE_RTREE, ENABLE_SESSION, ENABLE_STMTVTAB,
                                 ENABLE_UNLOCK_NOTIFY, ENABLE_UPDATE_DELETE_LIMIT, HAVE_ISNAN,
                                 LIKE_DOESNT_MATCH_BLOBS, MALLOC_SOFT_LIMIT=1024, MAX_ATTACHED=10,
                                 MAX_COLUMN=2000, MAX_COMPOUND_SELECT=500, MAX_DEFAULT_PAGE_SIZE=32768,
                                 MAX_EXPR_DEPTH=1000, MAX_FUNCTION_ARG=127, MAX_LENGTH=1000000000,
                                 MAX_LIKE_PATTERN_LENGTH=50000, MAX_MMAP_SIZE=0x7fff0000,
                                 MAX_PAGE_COUNT=1073741823, MAX_PAGE_SIZE=65536, MAX_SCHEMA_RETRY=25,
                                 MAX_SQL_LENGTH=1000000000, MAX_TRIGGER_DEPTH=1000,
                                 MAX_VARIABLE_NUMBER=250000, MAX_VDBE_OP=250000000, MAX_WORKER_THREADS=8,
                                 MUTEX_PTHREADS, OMIT_LOOKASIDE, SECURE_DELETE, SOUNDEX, SYSTEM_MALLOC,
                                 TEMP_STORE=1, THREADSAFE=1, USE_URI

4. What versions of what packages do you have installed? The output of pip freeze is helpful.

pip freeze

❯ pip freeze
arrow==1.2.3
binaryornot==0.4.4
-e git+https://github.com/beeware/briefcase.git@b62e9c91a85dcbf681c349df642d4fc3438e0c9c#egg=briefcase
build==0.10.0
cachetools==5.3.1
certifi==2023.5.7
cfgv==3.3.1
chardet==5.1.0
charset-normalizer==3.1.0
click==8.1.3
colorama==0.4.6
cookiecutter==2.1.1
coverage==7.2.7
coverage-conditional-plugin==0.9.0
distlib==0.3.6
execnet==1.9.0
filelock==3.12.1
gitdb==4.0.10
GitPython==3.1.31
identify==2.5.24
idna==3.4
iniconfig==2.0.0
Jinja2==3.1.2
jinja2-time==0.2.0
markdown-it-py==2.2.0
MarkupSafe==2.1.3
mdurl==0.1.2
nodeenv==1.8.0
packaging==23.1
pipdeptree==2.9.0
platformdirs==3.5.3
pluggy==1.0.0
pre-commit==3.3.2
psutil==5.9.5
Pygments==2.15.1
pyproject_api==1.5.1
pyproject_hooks==1.0.0
pytest==7.3.2
pytest-xdist==3.3.1
python-dateutil==2.8.2
python-slugify==8.0.1
PyYAML==6.0
requests==2.31.0
rich==13.4.1
setuptools-scm==7.1.0
six==1.16.0
smmap==5.0.0
text-unidecode==1.3
tomli_w==1.0.0
tox==4.6.0
typing_extensions==4.6.3
urllib3==2.0.3
virtualenv==20.23.0

5. What code shows the problem? Give us a specific commit of a specific repo that we can check out. If you've already worked around the problem, please provide a commit before that fix.

import pytest


def example(raise_exc: bool, enter_finally_cond: bool):
    try:
        if raise_exc:
            print("raising exception")
            raise Exception
        print("not raising exception")
    finally:
        if enter_finally_cond:
            print("in finally conditional")

    print("after finally")


@pytest.mark.parametrize("enter_finally_cond", (True, False))
def test_example_success(enter_finally_cond):
    example(raise_exc=False, enter_finally_cond=enter_finally_cond)


@pytest.mark.parametrize("enter_finally_cond", (True, False))
def test_example_fails(enter_finally_cond):
    with pytest.raises(Exception):
        example(raise_exc=True, enter_finally_cond=enter_finally_cond)

6. What commands should we run to reproduce the problem? Be specific. Include everything, even git clone, pip install, and so on. Explain like we're five!

• Run coverage run --branch -m pytest test.py && coverage report -m for the sample code above in a file named test.py.

Expected behavior
This example code should be 100% covered on Python 3.12 as on Python 3.11.

Additional Information

Example Runs

❯ ./briefcase/venv-3.11-briefcase/bin/python -m coverage run --branch -m pytest test.py && coverage report -m
=================================== test session starts ====================================
platform linux -- Python 3.11.3, pytest-7.4.0.dev127+g52cf700f, pluggy-1.0.0
rootdir: /home/russell/github/beeware
plugins: xdist-3.3.1
collected 4 items                                                                          

test.py ....                                                                         [100%]

==================================== 4 passed in 0.01s =====================================
Name      Stmts   Miss Branch BrPart  Cover   Missing
-----------------------------------------------------
test.py      17      0     13      0   100%
-----------------------------------------------------
TOTAL        17      0     13      0   100%

❯ ./briefcase/venv-3.12.0b1-briefcase/bin/python -m coverage run --branch -m pytest test.py && coverage report -m
=================================== test session starts ====================================
platform linux -- Python 3.12.0b1, pytest-7.3.1, pluggy-1.0.0
rootdir: /home/russell/github/beeware
plugins: xdist-3.3.1
collected 4 items                                                                          

test.py ....                                                                         [100%]

==================================== 4 passed in 0.02s =====================================
Name      Stmts   Miss Branch BrPart  Cover   Missing
-----------------------------------------------------
test.py      17      0     13      1    97%   12->exit
-----------------------------------------------------
TOTAL        17      0     13      1    97%

❯ ./briefcase/venv-3.12-briefcase/bin/python -m coverage run --branch -m pytest test.py && coverage report -m
=================================== test session starts ====================================
platform linux -- Python 3.12.0b2+, pytest-7.3.2, pluggy-1.0.0
rootdir: /home/russell/github/beeware
plugins: xdist-3.3.1
collected 4 items                                                                          

test.py ....                                                                         [100%]

==================================== 4 passed in 0.02s =====================================
Name      Stmts   Miss Branch BrPart  Cover   Missing
-----------------------------------------------------
test.py      17      0     13      1    97%   12->exit
-----------------------------------------------------
TOTAL        17      0     13      1    97%

[nedbat]

Thanks, I've reported this as a bug against 3.12: python/cpython#105658