lint: Replace pycodestyle with Flake8.

Flake8 combines pycodestyle with pyflakes and automatically gives us
support for noqa comments, parallelism, configuration files, plugins,
and easy editor integration.

Signed-off-by: Anders Kaseorg <anders@zulipchat.com>

.flake8

@@ -0,0 +1,59 @@
+[flake8]
+ignore =
+    # Each of these rules are ignored for the explained reason.
+
+    # "multiple spaces before operator"
+    # There are several typos here, but also several instances that are
+    # being used for alignment in dict keys/values using the `dict`
+    # constructor. We could fix the alignment cases by switching to the `{}`
+    # constructor, but it makes fixing this rule a little less
+    # straightforward.
+    E221,
+
+    # 'missing whitespace around arithmetic operator'
+    # This should possibly be cleaned up, though changing some of
+    # these may make the code less readable.
+    E226,
+
+    # "unexpected spaces around keyword / parameter equals"
+    # Many of these should be fixed, but many are also being used for
+    # alignment/making the code easier to read.
+    E251,
+
+    # "block comment should start with '#'"
+    # These serve to show which lines should be changed in files customized
+    # by the user. We could probably resolve one of E265 or E266 by
+    # standardizing on a single style for lines that the user might want to
+    # change.
+    E265,
+
+    # "too many leading '#' for block comment"
+    # Most of these are there for valid reasons.
+    E266,
+
+    # "expected 2 blank lines after class or function definition"
+    # Zulip only uses 1 blank line after class/function
+    # definitions; the PEP-8 recommendation results in super sparse code.
+    E302, E305,
+
+    # "module level import not at top of file"
+    # Most of these are there for valid reasons, though there might be a
+    # few that could be eliminated.
+    E402,
+
+    # "line too long"
+    # Zulip is a bit less strict about line length, and has its
+    # own check for this (see max_length)
+    E501,
+
+    # "line break before binary operator"
+    # This was obsoleted in favor of the opposite W504.
+    W503,
+
+    # "do not assign a lambda expression, use a def"
+    # Fixing these would probably reduce readability in most cases.
+    E731,
+
+exclude =
+    # third-party
+    zulip/integrations/perforce/git_p4.py,

requirements.txt

@@ -1,7 +1,7 @@
 crayons
 twine
 coverage>=4.4.1
-pycodestyle==2.3.1
+flake8
 mock
 pytest
 -e ./zulip

tools/lint

@@ -5,7 +5,6 @@ import argparse
 from zulint.command import add_default_linter_arguments, LinterConfig
 
 from custom_check import python_rules, non_py_rules
-from pep8 import check_pep8
 
 EXCLUDED_FILES = [
     # This is an external file that doesn't comply with our codestyle
@@ -24,6 +23,8 @@ def run() -> None:
 
     linter_config.external_linter('mypy', ['tools/run-mypy'], ['py'], pass_targets=False,
                                   description="Static type checker for Python (config: mypy.ini)")
+    linter_config.external_linter('flake8', ['flake8'], ['py'],
+                                  description="Standard Python linter (config: .flake8)")
 
     @linter_config.lint
     def custom_py() -> int:
@@ -39,12 +40,6 @@ def run() -> None:
             failed = failed or rule.check(by_lang, verbose=args.verbose)
         return 1 if failed else 0
 
-    @linter_config.lint
-    def pep8() -> int:
-        """Standard Python style linter on 50% of files (config: tools/linter_lib/pep8.py)"""
-        failed = check_pep8(by_lang['py'])
-        return 1 if failed else 0
-
     linter_config.do_lint()
 
 if __name__ == '__main__':

tools/pep8.py

@@ -1,97 +0,0 @@
-# This file has been copied and modified from the Zulip server repository
-# Original path: zulip/tools/linter_lib/pep8.py
-
-import subprocess
-
-from zulint.printer import print_err, colors
-
-from typing import List
-
-def check_pep8(files: List[str]) -> bool:
-
-    def run_pycodestyle(files: List[str], ignored_rules: List[str]) -> bool:
-        failed = False
-        color = next(colors)
-        pep8 = subprocess.Popen(
-            ['pycodestyle'] + files + ['--ignore={rules}'.format(rules=','.join(ignored_rules))],
-            stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
-        for line in iter(pep8.stdout.readline, b''):
-            print_err('pep8', color, line)
-            failed = True
-        return failed
-
-    failed = False
-    ignored_rules = [
-        # Each of these rules are ignored for the explained reason.
-
-        # "multiple spaces before operator"
-        # There are several typos here, but also several instances that are
-        # being used for alignment in dict keys/values using the `dict`
-        # constructor. We could fix the alignment cases by switching to the `{}`
-        # constructor, but it makes fixing this rule a little less
-        # straightforward.
-        'E221',
-
-        # 'missing whitespace around arithmetic operator'
-        # This should possibly be cleaned up, though changing some of
-        # these may make the code less readable.
-        'E226',
-
-        # "unexpected spaces around keyword / parameter equals"
-        # Many of these should be fixed, but many are also being used for
-        # alignment/making the code easier to read.
-        'E251',
-
-        # "block comment should start with '#'"
-        # These serve to show which lines should be changed in files customized
-        # by the user. We could probably resolve one of E265 or E266 by
-        # standardizing on a single style for lines that the user might want to
-        # change.
-        'E265',
-
-        # "too many leading '#' for block comment"
-        # Most of these are there for valid reasons.
-        'E266',
-
-        # "expected 2 blank lines after class or function definition"
-        # Zulip only uses 1 blank line after class/function
-        # definitions; the PEP-8 recommendation results in super sparse code.
-        'E302', 'E305',
-
-        # "module level import not at top of file"
-        # Most of these are there for valid reasons, though there might be a
-        # few that could be eliminated.
-        'E402',
-
-        # "line too long"
-        # Zulip is a bit less strict about line length, and has its
-        # own check for this (see max_length)
-        'E501',
-
-        # "line break before binary operator"
-        # This was obsoleted in favor of the opposite W504.
-        'W503',
-
-        # "do not assign a lambda expression, use a def"
-        # Fixing these would probably reduce readability in most cases.
-        'E731',
-    ]
-
-    # TODO: Clear up this list of violations.
-    IGNORE_FILES_PEPE261 = []
-
-    filtered_files = [fn for fn in files if fn not in IGNORE_FILES_PEPE261]
-    filtered_files_E261 = [fn for fn in files if fn in IGNORE_FILES_PEPE261]
-
-    if len(files) == 0:
-        return False
-    if not len(filtered_files) == 0:
-        failed = run_pycodestyle(filtered_files, ignored_rules)
-    if not len(filtered_files_E261) == 0:
-        # Adding an extra ignore rule for these files since they still remain in
-        # violation of PEP-E261.
-        failed_ignore_e261 = run_pycodestyle(filtered_files_E261, ignored_rules + ['E261'])
-        if not failed:
-            failed = failed_ignore_e261
-
-    return failed