AST parser fails on Python 3.9

[bnavigator]

These tests fail with Python 3.9.2 while they pass with 3.8.8:

[   32s] ============================= test session starts ==============================
[   32s] platform linux -- Python 3.9.2, pytest-6.2.2, py-1.10.0, pluggy-0.13.1
[   32s] rootdir: /home/abuild/rpmbuild/BUILD/requirementslib-1.5.16, configfile: setup.cfg
[   32s] plugins: hypothesis-6.8.1, timeout-1.4.2
[   32s] timeout: 300.0s
[   32s] timeout method: signal
[   32s] timeout func_only: False
[   32s] collected 189 items / 20 deselected / 169 selected
[   32s] 
[   32s] tests/unit/test_exceptions.py ......                                     [  3%]
[   34s] tests/unit/test_lockfile.py ...                                          [  5%]
[   34s] tests/unit/test_markers.py .........................................     [ 29%]
[   42s] tests/unit/test_metadata.py ..                                           [ 30%]
[   42s] tests/unit/test_pipfile.py ........                                      [ 35%]
[   42s] tests/unit/test_project.py ....................                          [ 47%]
[   46s] tests/unit/test_requirements.py ........................................ [ 71%]
[   46s] .....                                                                    [ 73%]
[   46s] tests/unit/test_setup_info.py .......F...F..                             [ 82%]
[   49s] tests/unit/test_uri.py ..                                                [ 83%]
[   49s] tests/unit/test_utils.py ............................                    [100%]
[   49s] 
[   49s] =================================== FAILURES ===================================
[   49s] _________________ test_ast_parser_handles_repeated_assignments _________________
[   49s] 
[   49s] setup_py_dir = PosixPath('/home/abuild/rpmbuild/BUILD/requirementslib-1.5.16/tests/fixtures/setup_py')
[   49s] 
[   49s]     def test_ast_parser_handles_repeated_assignments(setup_py_dir):
[   49s]         target = setup_py_dir.joinpath(
[   49s]             "package_with_repeated_assignments/setup.py"
[   49s]         ).as_posix()
[   49s]         parsed = ast_parse_setup_py(target)
[   49s]         analyzer = ast_parse_file(target)
[   49s]         assert parsed["name"] == "test_package_with_repeated_assignments"
[   49s] >       assert isinstance(parsed["version"], str) is False
[   49s] E       AssertionError: assert True is False
[   49s] E        +  where True = isinstance('os.environ', str)
[   49s] 
[   49s] tests/unit/test_setup_info.py:269: AssertionError

requirementslib/tests/fixtures/setup_py/package_with_repeated_assignments/setup.py

Line 6 in 6441984

version = os.environ["PACKAGE_VERSION"]

[   49s] _ test_ast_parser_handles_dependency_on_env_vars[env_vars1-expected_install_requires1] _
[   49s] 
[   49s] env_vars = {'READTHEDOCS': '1'}
[   49s] expected_install_requires = ['sphinx', 'sphinx-argparse']
[   49s] setup_py_dir = PosixPath('/home/abuild/rpmbuild/BUILD/requirementslib-1.5.16/tests/fixtures/setup_py')
[   49s] 
[   49s]     @pytest.mark.parametrize(
[   49s]         "env_vars, expected_install_requires",
[   49s]         [
[   49s]             ({"NOTHING": "1"}, []),
[   49s]             ({"READTHEDOCS": "1"}, ["sphinx", "sphinx-argparse"]),
[   49s]         ],
[   49s]     )
[   49s]     def test_ast_parser_handles_dependency_on_env_vars(
[   49s]         env_vars, expected_install_requires, setup_py_dir
[   49s]     ):
[   49s]         @contextlib.contextmanager
[   49s]         def modified_environ(**update):
[   49s]             env = os.environ
[   49s]             try:
[   49s]                 env.update(update)
[   49s]                 yield
[   49s]             finally:
[   49s]                 [env.pop(k) for k in update]
[   49s]     
[   49s]         with modified_environ(**env_vars):
[   49s]             parsed = ast_parse_setup_py(
[   49s]                 setup_py_dir.joinpath(
[   49s]                     "package_with_dependence_on_env_vars/setup.py"
[   49s]                 ).as_posix()
[   49s]             )
[   49s] >           assert list(sorted(parsed["install_requires"])) == list(
[   49s]                 sorted(expected_install_requires)
[   49s]             )
[   49s] E           AssertionError: assert ['docs'] == ['sphinx', 'sphinx-argparse']
[   49s] E             At index 0 diff: 'docs' != 'sphinx'
[   49s] E             Right contains one more item: 'sphinx-argparse'
[   49s] E             Use -v to get the full diff
[   49s] 
[   49s] tests/unit/test_setup_info.py:327: AssertionError

requirementslib/tests/fixtures/setup_py/package_with_dependence_on_env_vars/setup.py

Line 14 in 6441984

install_requires=extras_require["docs"] if "READTHEDOCS" in os.environ else [],