mypy-runner

mypy-runner

Ease your way into static type checking by focusing on a small set of problems at a time.

It can be quite challenging to get an existing code base to pass mypy's checks, even at its most lenient settings, and unfortunately, until you do you can't use mypy as part of your CI/CD process.

mypy-runner lets you gradually introduce type checking by identifying a subset of files and errors to check:

• choose a set of files and errors to check
• get tests passing and enforce them in your CI and pre-commit hooks
• repeat

Features

mypy-runner adds the following features to mypy:

• Display colorized output
• Convert specific errors to warnings
• Filter specific errors and warnings
• Automatically insert missing typing imports (see --add-missing-imports below)

Compatibility

mypy-runner supports mypy 0.730 and higher.

Options

::

usage: mypyrun [-h] [--version] [--daemon] [--select SELECT [SELECT ...]] [--ignore IGNORE [IGNORE ...]] [--warn WARN [WARN ...]] [--color] [--show-ignored] [--add-missing-imports] [--options OPTIONS] [--config-file CONFIG_FILE]
                  [--files FILES [FILES ...]] [--warning-filters WARNING_FILTERS [WARNING_FILTERS ...]] [--error-filters ERROR_FILTERS [ERROR_FILTERS ...]] [--mypy-executable MYPY_EXECUTABLE]
                  [ARG [ARG ...]]

positional arguments:
  ARG                   Regular mypy flags and files (precede with --)

optional arguments:
  -h, --help            show this help message and exit
  --version             show program's version number and exit
  --daemon              Run mypy in daemon mode (inverse: --no-daemon)
  --select SELECT [SELECT ...], -s SELECT [SELECT ...]
                        Errors to check
  --ignore IGNORE [IGNORE ...], -i IGNORE [IGNORE ...]
                        Errors to skip
  --warn WARN [WARN ...], -w WARN [WARN ...]
                        Errors to convert into warnings
  --color               Colorize output (inverse: --no-color)
  --show-ignored, -x    Show errors that have been ignored (darker if using color)
  --add-missing-imports
                        Add missing typing imports. This will detect mypy errors related to missing classes from the typing module and automatically insert them into the file
  --options OPTIONS, -o OPTIONS
                        Override the default options to use the namedconfiguration section (e.g. pass --options=foo to use the [mypyrun-foo] section)
  --config-file CONFIG_FILE, -c CONFIG_FILE
                        Specific configuration file.
  --files FILES [FILES ...]
                        Files to isolate (triggers use of 'active'options for these files)
  --warning-filters WARNING_FILTERS [WARNING_FILTERS ...]
                        Regular expression to ignore messages flagged as warnings
  --error-filters ERROR_FILTERS [ERROR_FILTERS ...]
                        Regular expression to ignore messages flagged as errors
  --mypy-executable MYPY_EXECUTABLE
                        Path to the mypy executable

As with tools like flake8, you use specific error codes to enable or disable error output. Errors that are ignored or converted into warnings will not trigger a non-zero exit status.

Configuration

mypyrun looks for a [mypyrun] section in either mypy.ini or mypyrun.ini.

Here's an example configuration file:

.. code-block:: ini

[mypyrun]

# run dmypy instead of mypy
daemon = true

# only display these errors
select =
    not_defined,
    return_expected,
    return_not_expected,
    incompatible_subclass_attr,

# all other errors are warnings
warn = *

# filter errors generated from these paths:
exclude =
    thirdparty/*,

# pass these paths to mypy
paths =
    arnold/python,
    houdini/python,
    katana/python,
    mari/python,
    maya/python,
    nuke/python,
    python/packages,