Advanced usage¶
Automated tests¶
You can also execute pycodestyle
tests from Python code. For example, this
can be highly useful for automated testing of coding style conformance
in your project:
import unittest
import pycodestyle
class TestCodeFormat(unittest.TestCase):
def test_conformance(self):
"""Test that we conform to PEP-8."""
style = pycodestyle.StyleGuide(quiet=True)
result = style.check_files(['file1.py', 'file2.py'])
self.assertEqual(result.total_errors, 0,
"Found code style errors (and warnings).")
There’s also a shortcut for checking a single file:
import pycodestyle
fchecker = pycodestyle.Checker('testing/data/E27.py', show_source=True)
file_errors = fchecker.check_all()
print("Found %s errors (and warnings)" % file_errors)
Configuring tests¶
You can configure automated pycodestyle
tests in a variety of ways.
For example, you can pass in a path to a configuration file that pycodestyle
should use:
import pycodestyle
style = pycodestyle.StyleGuide(config_file='/path/to/tox.ini')
You can also set specific options explicitly:
style = pycodestyle.StyleGuide(ignore=['E501'])
Skip file header¶
Another example is related to the feature request #143: skip a number of lines at the beginning and the end of a file. This use case is easy to implement through a custom wrapper for the PEP 8 library:
#!python
import pycodestyle
LINES_SLICE = slice(14, -20)
class StyleGuide(pycodestyle.StyleGuide):
"""This subclass of pycodestyle.StyleGuide will skip the first and last lines
of each file."""
def input_file(self, filename, lines=None, expected=None, line_offset=0):
if lines is None:
assert line_offset == 0
line_offset = LINES_SLICE.start or 0
lines = pycodestyle.readlines(filename)[LINES_SLICE]
return super(StyleGuide, self).input_file(
filename, lines=lines, expected=expected, line_offset=line_offset)
if __name__ == '__main__':
style = StyleGuide(parse_argv=True, config_file=True)
report = style.check_files()
if report.total_errors:
raise SystemExit(1)
This module declares a lines’ window which skips 14 lines at the beginning
and 20 lines at the end. If there’s no line to skip at the end, it could be
changed with LINES_SLICE = slice(14, None)
for example.
You can save it in a file and use it with the same options as the
original pycodestyle
.