v4.0.2

Compare Source

False Positives Fixed

• Fix false positive for invalid-name on a partially uninferable module-level constant.

  Closes #​10652

• Fix a false positive for invalid-name on exclusive module-level assignments
  composed of three or more branches. We won't raise disallowed-name on module-level names that can't be inferred
  until a further refactor to remove this false negative is done.

  Closes #​10664

• Fix false positive for invalid-name for TypedDict instances.

  Closes #​10672

v4.0.1

Compare Source

What's new in Pylint 4.0.1?

Release date: 2025-10-14

False Positives Fixed

• Exclude __all__ and __future__.annotations from unused-variable.

  Closes #​10019

• Fix false-positive for bare-name-capture-pattern if a case guard is used.

  Closes #​10647

• Check enums created with the Enum() functional syntax to pass against the
  --class-rgx for the invalid-name check, like other enums.

  Closes #​10660

v4.0.0

Compare Source

• Pylint now supports Python 3.14.

• Pylint's inference engine (astroid) is now much more precise,
  understanding implicit booleanness and ternary expressions. (Thanks @​zenlyj!)

Consider this example:

class Result:
    errors: dict | None = None

result = Result()
if result.errors:
    result.errors[field_key]

##### inference engine understands result.errors cannot be None
##### pylint no longer raises unsubscriptable-object

The required astroid version is now 4.0.0. See the astroid changelog for additional fixes, features, and performance improvements applicable to pylint.

• Handling of invalid-name at the module level was patchy. Now,
  module-level constants that are reassigned are treated as variables and checked
  against --variable-rgx rather than --const-rgx. Module-level lists,
  sets, and objects can pass against either regex.

Here, LIMIT is reassigned, so pylint only uses --variable-rgx:

LIMIT = 500  # [invalid-name]
if sometimes:
    LIMIT = 1  # [invalid-name]

If this is undesired, refactor using exclusive assignment so that it is
evident that this assignment happens only once:

if sometimes:
    LIMIT = 1
else:
    LIMIT = 500  # exclusive assignment: uses const regex, no warning

Lists, sets, and objects still pass against either const-rgx or variable-rgx
even if reassigned, but are no longer completely skipped:

MY_LIST = []
my_list = []
My_List = []  # [invalid-name]

Remember to adjust the regexes and allow lists to your liking.

Breaking Changes

• invalid-name now distinguishes module-level constants that are assigned only once
  from those that are reassigned and now applies --variable-rgx to the latter. Values
  other than literals (lists, sets, objects) can pass against either the constant or
  variable regexes (e.g. "LOGGER" or "logger" but not "LoGgEr").

  Remember that --good-names or --good-names-rgxs can be provided to explicitly
  allow good names.

  Closes #​3585

• The unused pylintrc argument to PyLinter.__init__() is deprecated
  and will be removed.

  Refs #​6052

• Commented out code blocks such as # bar() # TODO: remove dead code will no longer emit fixme.

  Refs #​9255

• pyreverse Run was changed to no longer call sys.exit() in its __init__.
  You should now call Run(args).run() which will return the exit code instead.
  Having a class that always raised a SystemExit exception was considered a bug.

  Normal usage of pyreverse through the CLI will not be affected by this change.

  Refs #​9689

• The suggestion-mode option was removed, as pylint now always emits user-friendly hints instead
  of false-positive error messages. You should remove it from your conf if it's defined.

  Refs #​9962

• The async.py checker module has been renamed to async_checker.py since async is a Python keyword
  and cannot be imported directly. This allows for better testing and extensibility of the async checker functionality.

  Refs #​10071

• The message-id of continue-in-finally was changed from E0116 to W0136. The warning is
  now emitted for every Python version since it will raise a syntax warning in Python 3.14.
  See PEP 765 - Disallow return/break/continue that exit a finally block.

  Refs #​10480

• Removed support for nmp.NaN alias for numpy.NaN being recognized in ':ref:nan-comparison'. Use np or numpy instead.

  Refs #​10583

• Version requirement for isort has been bumped to >=5.0.0.
  The internal compatibility for older isort versions exposed via pylint.utils.IsortDriver has
  been removed.

  Refs #​10637

New Features

• comparison-of-constants now uses the unicode from the ast instead of reformatting from
  the node's values preventing some bad formatting due to utf-8 limitation. The message now uses
  " instead of ' to better work with what the python ast returns.

  Refs #​8736

• Enhanced pyreverse to properly distinguish between UML relationship types (association, aggregation, composition) based on object ownership semantics. Type annotations without assignment are now treated as associations, parameter assignments as aggregations, and object instantiation as compositions.

  Closes #​9045
  Closes #​9267

• The fixme check can now search through docstrings as well as comments, by using
  check-fixme-in-docstring = true in the [tool.pylint.miscellaneous] section.

  Closes #​9255

• The use-implicit-booleaness-not-x checks now distinguish between comparisons
  used in boolean contexts and those that are not, enabling them to provide more accurate refactoring suggestions.

  Closes #​9353

• The verbose option now outputs the filenames of the files that have been checked.
  Previously, it only included the number of checked and skipped files.

  Closes #​9357

• colorized reporter now colorizes messages/categories that have been configured as fail-on in red inverse.
  This makes it easier to quickly find the errors that are causing pylint CI job failures.

  Closes #​9898

• Enhanced support for @​property decorator in pyreverse to correctly display return types of annotated properties when generating class diagrams.

  Closes #​10057

• Add --max-depth option to pyreverse to control diagram complexity. A depth of 0 shows only top-level packages, 1 shows one level of subpackages, etc.
  This helps manage visualization of large codebases by limiting the depth of displayed packages and classes.

  Refs #​10077

• Handle deferred evaluation of annotations in Python 3.14.

  Closes #​10149

• Enhanced pyreverse to properly detect aggregations for comprehensions (list, dict, set, generator).

  Closes #​10236

• pyreverse: add support for colorized output when using output format mmd (MermaidJS) and html.

  Closes #​10242

• pypy 3.11 is now officially supported.

  Refs #​10287

• Add support for Python 3.14.

  Refs #​10467

• Add naming styles for ParamSpec and TypeVarTuple that align with the TypeVar style.

  Refs #​10541

New Checks

• Add match-statements checker and the following message:
  bare-name-capture-pattern.
  This will emit an error message when a name capture pattern is used in a match statement which would make the remaining patterns unreachable.
  This code is a SyntaxError at runtime.

  Closes #​7128

• Add new check async-context-manager-with-regular-with to detect async context managers used with regular with statements instead of async with.

  Refs #​10408

• Add break-in-finally warning. Using break inside the finally clause
  will raise a syntax warning in Python 3.14.
  See PEP 765 - Disallow return/break/continue that exit a finally block <https://peps.python.org/pep-0765/>_.

  Refs #​10480

• Add new checks for invalid uses of class patterns in :keyword:match.

  • :ref:invalid-match-args-definition is emitted if :py:data:object.__match_args__ isn't a tuple of strings.
  • :ref:too-many-positional-sub-patterns if there are more positional sub-patterns than specified in :py:data:object.__match_args__.
  • :ref:multiple-class-sub-patterns if there are multiple sub-patterns for the same attribute.

  Refs #​10559

• Add additional checks for suboptimal uses of class patterns in :keyword:match.

  • :ref:match-class-bind-self is emitted if a name is bound to self instead of
    using an as pattern.
  • :ref:match-class-positional-attributes is emitted if a class pattern has positional
    attributes when keywords could be used.

  Refs #​10587

• Add a consider-math-not-float message. float("nan") and float("inf") are slower
  than their counterpart math.inf and math.nan by a factor of 4 (notwithstanding
  the initial import of math) and they are also not well typed when using mypy.
  This check also catches typos in float calls as a side effect.

  The :ref:pylint.extensions.code_style need to be activated for this check to work.

  Refs #​10621

False Positives Fixed

• Fix a false positive for used-before-assignment when a variable defined under
  an if and via a named expression (walrus operator) is used later when guarded
  under the same if test.

  Closes #​10061

• Fix :ref:no-name-in-module for members of concurrent.futures with Python 3.14.

  Closes #​10632

False Negatives Fixed

• Fix false negative for used-before-assignment when a TYPE_CHECKING import is used as a type annotation prior to erroneous usage.

  Refs #​8893

• Match cases are now counted as edges in the McCabe graph and will increase the complexity accordingly.

  Refs #​9667

• Check module-level constants with type annotations for invalid-name.
  Remember to adjust const-naming-style or const-rgx to your liking.

  Closes #​9770

• Fix false negative where function-redefined (E0102) was not reported for functions with a leading underscore.

  Closes #​9894

• We now raise a logging-too-few-args for format string with no
  interpolation arguments at all (i.e. for something like logging.debug("Awaiting process %s")
  or logging.debug("Awaiting process {pid}")). Previously we did not raise for such case.

  Closes #​9999

• Fix false negative for used-before-assignment when a function is defined inside a TYPE_CHECKING guard block and used later.

  Closes #​10028

• Fix a false negative for possibly-used-before-assignment when a variable is conditionally defined
  and later assigned to a type-annotated variable.

  Closes #​10421

• Fix false negative for deprecated-module when a __import__ method is used instead of import sentence.

  Refs #​10453

• Count match cases for too-many-branches check.

  Refs #​10542

• Fix false-negative where :ref:unused-import was not reported for names referenced in a preceding global statement.

  Refs #​10633

Other Bug Fixes

• When displaying unicode with surrogates (or other potential UnicodeEncodeError),
  pylint will now display a '?' character (using encode(encoding="utf-8", errors="replace"))
  instead of crashing. The functional tests classes are also updated to handle this case.

  Closes #​8736

• Fixed unidiomatic-typecheck only checking left-hand side.

  Closes #​10217

• Fix a crash caused by malformed format strings when using .format with keyword arguments.

  Closes #​10282

• Fix false positive inconsistent-return-statements when using quit() or exit() functions.

  Closes #​10508

• Fix a crash in :ref:nested-min-max when using builtins.min or builtins.max
  instead of min or max directly.

  Closes #​10626

• Fixed a crash in :ref:unnecessary-dict-index-lookup when the index of an enumerated list
  was deleted inside a for loop.

  Closes #​10627

Other Changes

• Remove support for launching pylint with Python 3.9.
  Code that supports Python 3.9 can still be linted with the --py-version=3.9 setting.

  Refs #​10405

Internal Changes

• Modified test framework to allow for different test output for different Python versions.

  Refs #​10382

v9.0.0

Compare Source

pytest 9.0.0 (2025-11-05)

New features

• #​1367: Support for subtests has been added.

  subtests <subtests> are an alternative to parametrization, useful in situations where the parametrization values are not all known at collection time.

  Example:

  def contains_docstring(p: Path) -> bool:
      """Return True if the given Python file contains a top-level docstring."""
      ...
  
  def test_py_files_contain_docstring(subtests: pytest.Subtests) -> None:
      for path in Path.cwd().glob("*.py"):
          with subtests.test(path=str(path)):
              assert contains_docstring(path)

  Each assert failure or error is caught by the context manager and reported individually, giving a clear picture of all files that are missing a docstring.

  In addition, unittest.TestCase.subTest is now also supported.

  This feature was originally implemented as a separate plugin in pytest-subtests, but since then has been merged into the core.

  [!NOTE]
  This feature is experimental and will likely evolve in future releases. By that we mean that we might change how subtests are reported on failure, but the functionality and how to use it are stable.

• #​13743: Added support for native TOML configuration files.

  While pytest, since version 6, supports configuration in pyproject.toml files under [tool.pytest.ini_options],
  it does so in an "INI compatibility mode", where all configuration values are treated as strings or list of strings.
  Now, pytest supports the native TOML data model.

  In pyproject.toml, the native TOML configuration is under the [tool.pytest] table.

  # pyproject.toml
  [tool.pytest]
  minversion = "9.0"
  addopts = ["-ra", "-q"]
  testpaths = [
      "tests",
      "integration",
  ]

  The [tool.pytest.ini_options] table remains supported, but both tables cannot be used at the same time.

  If you prefer to use a separate configuration file, or don't use pyproject.toml, you can use pytest.toml or .pytest.toml:

  # pytest.toml or .pytest.toml
  [pytest]
  minversion = "9.0"
  addopts = ["-ra", "-q"]
  testpaths = [
      "tests",
      "integration",
  ]

  The documentation now (sometimes) shows configuration snippets in both TOML and INI formats, in a tabbed interface.

  See config file formats for full details.

• #​13823: Added a "strict mode" enabled by the strict configuration option.

  When set to true, the strict option currently enables

  • strict_config
  • strict_markers
  • strict_parametrization_ids
  • strict_xfail

  The individual strictness options can be explicitly set to override the global strict setting.

  The previously-deprecated --strict command-line flag now enables strict mode.

  If pytest adds new strictness options in the future, they will also be enabled in strict mode.
  Therefore, you should only enable strict mode if you use a pinned/locked version of pytest,
  or if you want to proactively adopt new strictness options as they are added.

  See strict mode for more details.

• #​13737: Added the strict_parametrization_ids configuration option.

  When set, pytest emits an error if it detects non-unique parameter set IDs,
  rather than automatically making the IDs unique by adding 0, 1, ... to them.
  This can be particularly useful for catching unintended duplicates.

• #​13072: Added support for displaying test session progress in the terminal tab using the OSC 9;4; ANSI sequence.
  When pytest runs in a supported terminal emulator like ConEmu, Gnome Terminal, Ptyxis, Windows Terminal, Kitty or Ghostty,
  you'll see the progress in the terminal tab or window,
  allowing you to monitor pytest's progress at a glance.

  This feature is automatically enabled when running in a TTY. It is implemented as an internal plugin. If needed, it can be disabled as follows:

  • On a user level, using -p no:terminalprogress on the command line or via an environment variable PYTEST_ADDOPTS='-p no:terminalprogress'.
  • On a project configuration level, using addopts = "-p no:terminalprogress".

• #​478: Support PEP420 (implicit namespace packages) as --pyargs target when consider_namespace_packages is true in the config.

  Previously, this option only impacted package imports, now it also impacts tests discovery.

• #​13678: Added a new faulthandler_exit_on_timeout configuration option set to "false" by default to let faulthandler interrupt the pytest process after a timeout in case of deadlock.

  Previously, a faulthandler timeout would only dump the traceback of all threads to stderr, but would not interrupt the pytest process.

  -- by ogrisel.

• #​13829: Added support for configuration option aliases via the aliases parameter in Parser.addini() <pytest.Parser.addini>.

  Plugins can now register alternative names for configuration options,
  allowing for more flexibility in configuration naming and supporting backward compatibility when renaming options.
  The canonical name always takes precedence if both the canonical name and an alias are specified in the configuration file.

Improvements in existing functionality

• #​13330: Having pytest configuration spread over more than one file (for example having both a pytest.ini file and pyproject.toml with a [tool.pytest.ini_options] table) will now print a warning to make it clearer to the user that only one of them is actually used.

  -- by sgaist

• #​13574: The single argument --version no longer loads the entire plugin infrastructure, making it faster and more reliable when displaying only the pytest version.

  Passing --version twice (e.g., pytest --version --version) retains the original behavior, showing both the pytest version and plugin information.

  [!NOTE]
  Since --version is now processed early, it only takes effect when passed directly via the command line. It will not work if set through other mechanisms, such as PYTEST_ADDOPTS or addopts.

• #​13823: Added strict_xfail as an alias to the xfail_strict option,
  strict_config as an alias to the --strict-config flag,
  and strict_markers as an alias to the --strict-markers flag.
  This makes all strictness options consistently have configuration options with the prefix strict_.

• #​13700: --junitxml no longer prints the generated xml file summary at the end of the pytest session when --quiet is given.

• #​13732: Previously, when filtering warnings, pytest would fail if the filter referenced a class that could not be imported. Now, this only outputs a message indicating the problem.

• #​13859: Clarify the error message for pytest.raises() when a regex match fails.

• #​13861: Better sentence structure in a test's expected error message. Previously, the error message would be "expected exception must be <expected>, but got <actual>". Now, it is "Expected <expected>, but got <actual>".

Removals and backward incompatible breaking changes

• #​12083: Fixed a bug where an invocation such as pytest a/ a/b would cause only tests from a/b to run, and not other tests under a/.

  The fix entails a few breaking changes to how such overlapping arguments and duplicates are handled:

  1. pytest a/b a/ or pytest a/ a/b are equivalent to pytest a; if an argument overlaps another arguments, only the prefix remains.
  2. pytest x.py x.py is equivalent to pytest x.py; previously such an invocation was taken as an explicit request to run the tests from the file twice.

  If you rely on these behaviors, consider using --keep-duplicates <duplicate-paths>, which retains its existing behavior (including the bug).

• #​13719: Support for Python 3.9 is dropped following its end of life.

• #​13766: Previously, pytest would assume it was running in a CI/CD environment if either of the environment variables $CI or $BUILD_NUMBER was defined;
  now, CI mode is only activated if at least one of those variables is defined and set to a non-empty value.

• #​13779: PytestRemovedIn9Warning deprecation warnings are now errors by default.

  Following our plan to remove deprecated features with as little disruption as
  possible, all warnings of type PytestRemovedIn9Warning now generate errors
  instead of warning messages by default.

  The affected features will be effectively removed in pytest 9.1, so please consult the
  deprecations section in the docs for directions on how to update existing code.

  In the pytest 9.0.X series, it is possible to change the errors back into warnings as a
  stopgap measure by adding this to your pytest.ini file:

  [pytest]
  filterwarnings =
      ignore::pytest.PytestRemovedIn9Warning

  But this will stop working when pytest 9.1 is released.

  If you have concerns about the removal of a specific feature, please add a
  comment to 13779.

Deprecations (removal in next major release)

• #​13807: monkeypatch.syspath_prepend() <pytest.MonkeyPatch.syspath_prepend> now issues a deprecation warning when the prepended path contains legacy namespace packages (those using pkg_resources.declare_namespace()).
  Users should migrate to native namespace packages (420).
  See monkeypatch-fixup-namespace-packages for details.

Bug fixes

• #​13445: Made the type annotations of pytest.skip and friends more spec-complaint to have them work across more type checkers.

• #​13537: Fixed a bug in which ExceptionGroup with only Skipped exceptions in teardown was not handled correctly and showed as error.

• #​13598: Fixed possible collection confusion on Windows when short paths and symlinks are involved.

• #​13716: Fixed a bug where a nonsensical invocation like pytest x.py[a] (a file cannot be parametrized) was silently treated as pytest x.py. This is now a usage error.

• #​13722: Fixed a misleading assertion failure message when using pytest.approx on mappings with differing lengths.

• #​13773: Fixed the static fixture closure calculation to properly consider transitive dependencies requested by overridden fixtures.

• #​13816: Fixed pytest.approx which now returns a clearer error message when comparing mappings with different keys.

• #​13849: Hidden .pytest.ini files are now picked up as the config file even if empty.
  This was an inconsistency with non-hidden pytest.ini.

• #​13865: Fixed --show-capture with --tb=line.

• #​13522: Fixed pytester in subprocess mode ignored all :attr`pytester.plugins <pytest.Pytester.plugins>` except the first.

  Fixed pytester in subprocess mode silently ignored non-str pytester.plugins <pytest.Pytester.plugins>.
  Now it errors instead.
  If you are affected by this, specify the plugin by name, or switch the affected tests to use pytester.runpytest_inprocess <pytest.Pytester.runpytest_inprocess> explicitly instead.

Packaging updates and notes for downstreams

• #​13791: Minimum requirements on iniconfig and packaging were bumped to 1.0.1 and 22.0.0, respectively.

Contributor-facing changes

• #​12244: Fixed self-test failures when TERM=dumb.
• #​12474: Added scheduled GitHub Action Workflow to run Sphinx linkchecks in repo documentation.
• #​13621: pytest's own testsuite now handles the lsof command hanging (e.g. due to unreachable network filesystems), with the affected selftests being skipped after 10 seconds.
• #​13638: Fixed deprecated gh pr new command in scripts/prepare-release-pr.py.
  The script now uses gh pr create which is compatible with GitHub CLI v2.0+.
• #​13695: Flush stdout and stderr in Pytester.run to avoid truncated outputs in test_faulthandler.py::test_timeout on CI -- by ogrisel.
• #​13771: Skip test_do_not_collect_symlink_siblings on Windows environments without symlink support to avoid false negatives.
• #​13841: tox>=4 is now required when contributing to pytest.
• #​13625: Added missing docstrings to pytest_addoption(), pytest_configure(), and cacheshow() functions in cacheprovider.py.

Miscellaneous internal changes

• #​13830: Configuration overrides (-o/--override-ini) are now processed during startup rather than during config.getini() <pytest.Config.getini>.

v0.14.4

Compare Source

Released on 2025-11-06.

Preview features

• [formatter] Allow newlines after function headers without docstrings (#​21110)
• [formatter] Avoid extra parentheses for long match patterns with as captures (#​21176)
• [refurb] Expand fix safety for keyword arguments and Decimals (FURB164) (#​21259)
• [refurb] Preserve argument ordering in autofix (FURB103) (#​20790)

Bug fixes

• [server] Fix missing diagnostics for notebooks (#​21156)
• [flake8-bugbear] Ignore non-NFKC attribute names in B009 and B010 (#​21131)
• [refurb] Fix false negative for underscores before sign in Decimal constructor (FURB157) (#​21190)
• [ruff] Fix false positives on starred arguments (RUF057) (#​21256)

Rule changes

• [airflow] extend deprecated argument concurrency in airflow..DAG (AIR301) (#​21220)

Documentation

• Improve extend docs (#​21135)
• [flake8-comprehensions] Fix typo in C416 documentation (#​21184)
• Revise Ruff setup instructions for Zed editor (#​20935)

Other changes

• Make ruff analyze graph work with jupyter notebooks (#​21161)

Contributors

• @​chirizxc
• @​Lee-W
• @​musicinmybrain
• @​MichaReiser
• @​tjkuson
• @​danparizher
• @​renovate
• @​ntBre
• @​gauthsvenkat
• @​LoicRiegel