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The package provides base classes and utils for flake8 plugin writing

Project description


pypi Python: 3.6+ Downloads Build Status Code coverage License: MIT Code style: black

The package provides base classes and utils for flake8 plugin writing.


pip install flake8-plugin-utils


Write simple plugin

from flake8_plugin_utils import Error, Visitor, Plugin

class MyError(Error):
    code = 'X100'
    message = 'my error'

class MyVisitor(Visitor):
    def visit_ClassDef(self, node):
        self.error_from_node(MyError, node)

class MyPlugin(Plugin):
    name = 'MyPlugin'
    version = '0.1.0'
    visitors = [MyVisitor]

and test it with pytest

from flake8_plugin_utils import assert_error, assert_not_error

def test_code_with_error():
    assert_error(MyVisitor, 'class Y: pass', MyError)

def test_code_without_error():
    assert_not_error(MyVisitor, 'x = 1')


Your Errors can take formatting arguments in their message:

from flake8_plugin_utils import Error, Visitor, assert_error

class MyFormattedError(Error):
    code = 'X101'
    message = 'my error with {thing}'

class MyFormattedVisitor(Visitor):
    def visit_ClassDef(self, node):
        self.error_from_node(MyFormattedError, node,

def test_code_with_error():
        'class Y: pass',



Change Log


  • ...

1.0.0 - 2019-05-23

  • add message formatting to Error

0.2.1 - 2019-04-01

  • don`t strip before src dedent in _error_from_src
  • add is_none, is_true, is_false util functions

0.2.0 - 2019.02.21

  • add assert methods

0.1.0 - 2019.02.09

  • initial

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