test_export_uses_requirements_txt_format_by_default TypeError: expected str, bytes or os.PathLike object, not NoneType

test_export_groups[--with opt-foo==1.0.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.6" and python_version < "4.0"\nopt==2.2.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.6" and python_version < "4.0"\n] TypeError: expected str, bytes or os.PathLike object, not NoneType

test_export_includes_extras_by_flag[feature_bar-bar==1.1.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.6" and python_version < "4.0"\nfoo==1.0.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.6" and python_version < "4.0"\n] TypeError: expected str, bytes or os.PathLike object, not NoneType

test_export_groups[--only dev-baz==2.0.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.6" and python_version < "4.0"\n] TypeError: expected str, bytes or os.PathLike object, not NoneType

test_export_groups[--without opt-foo==1.0.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.6" and python_version < "4.0"\n] TypeError: expected str, bytes or os.PathLike object, not NoneType

test_extras_conflicts_all_extras TypeError: expected str, bytes or os.PathLike object, not NoneType

test_export_groups[-foo==1.0.0 ; python_version >= "2.7" and python_version < "2.8" or python_version >= "3.6" and python_version < "4.0"\n] TypeError: expected str, bytes or os.PathLike object, not NoneType

test_export_with_urls TypeError: expected str, bytes or os.PathLike object, not NoneType

test_export_with_all_extras TypeError: expected str, bytes or os.PathLike object, not NoneType