Add tox -e flake8, fix flake8 errors

8 files changed, 126 insertions, 97 deletions

diff --git a/setup.py b/setup.py
index 47e4f94..c7282d6 100644
--- a/setup.py
+++ b/setup.py
@@ -25,6 +25,7 @@ from setuptools import setup, find_packages
 def read(*rnames):
     return open(os.path.join(os.path.dirname(__file__), *rnames)).read()
 
+
 def alltests():
     import os
     import sys
@@ -40,55 +41,57 @@ def alltests():
     suites = list(zope.testrunner.find.find_suites(options))
     return unittest.TestSuite(suites)
 
+
 tests_require = [
     'zope.testrunner',
 ]
 
-setup(name='zope.exceptions',
-      version='4.4.dev0',
-      author='Zope Foundation and Contributors',
-      author_email='zope-dev@zope.org',
-      description='Zope Exceptions',
-      long_description=(read('README.rst') + '\n\n' +
-                        read('CHANGES.rst')),
-      keywords='zope exceptions',
-      classifiers=[
-          'Development Status :: 5 - Production/Stable',
-          'Environment :: Web Environment',
-          'Intended Audience :: Developers',
-          'License :: OSI Approved :: Zope Public License',
-          'Programming Language :: Python',
-          'Programming Language :: Python :: 2',
-          'Programming Language :: Python :: 2.7',
-          'Programming Language :: Python :: 3',
-          'Programming Language :: Python :: 3.5',
-          'Programming Language :: Python :: 3.6',
-          'Programming Language :: Python :: 3.7',
-          'Programming Language :: Python :: 3.8',
-          'Programming Language :: Python :: Implementation :: CPython',
-          'Programming Language :: Python :: Implementation :: PyPy',
-          'Natural Language :: English',
-          'Operating System :: OS Independent',
-          'Topic :: Internet :: WWW/HTTP',
-          'Framework :: Zope :: 3',
-      ],
-      url='https://github.com/zopefoundation/zope.exceptions',
-      license='ZPL 2.1',
-      packages=find_packages('src'),
-      package_dir={'': 'src'},
-      namespace_packages=['zope'],
-      install_requires=[
-          'setuptools',
-          'zope.interface',
-      ],
-      tests_require=[
-          'zope.testrunner',
-      ],
-      test_suite='__main__.alltests',
-      include_package_data=True,
-      zip_safe=False,
-      extras_require={
-          'docs': ['Sphinx', 'repoze.sphinx.autointerface'],
-          'test': tests_require,
-      },
+setup(
+    name='zope.exceptions',
+    version='4.4.dev0',
+    author='Zope Foundation and Contributors',
+    author_email='zope-dev@zope.org',
+    description='Zope Exceptions',
+    long_description=(read('README.rst') + '\n\n' +
+                      read('CHANGES.rst')),
+    keywords='zope exceptions',
+    classifiers=[
+        'Development Status :: 5 - Production/Stable',
+        'Environment :: Web Environment',
+        'Intended Audience :: Developers',
+        'License :: OSI Approved :: Zope Public License',
+        'Programming Language :: Python',
+        'Programming Language :: Python :: 2',
+        'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
+        'Programming Language :: Python :: Implementation :: CPython',
+        'Programming Language :: Python :: Implementation :: PyPy',
+        'Natural Language :: English',
+        'Operating System :: OS Independent',
+        'Topic :: Internet :: WWW/HTTP',
+        'Framework :: Zope :: 3',
+    ],
+    url='https://github.com/zopefoundation/zope.exceptions',
+    license='ZPL 2.1',
+    packages=find_packages('src'),
+    package_dir={'': 'src'},
+    namespace_packages=['zope'],
+    install_requires=[
+        'setuptools',
+        'zope.interface',
+    ],
+    tests_require=[
+        'zope.testrunner',
+    ],
+    test_suite='__main__.alltests',
+    include_package_data=True,
+    zip_safe=False,
+    extras_require={
+        'docs': ['Sphinx', 'repoze.sphinx.autointerface'],
+        'test': tests_require,
+    },
 )
diff --git a/src/zope/__init__.py b/src/zope/__init__.py
index 2cdb0e4..656dc0f 100644
--- a/src/zope/__init__.py
+++ b/src/zope/__init__.py
@@ -1 +1 @@
-__import__('pkg_resources').declare_namespace(__name__) # pragma: no cover
+__import__('pkg_resources').declare_namespace(__name__)  # pragma: no cover
diff --git a/src/zope/exceptions/__init__.py b/src/zope/exceptions/__init__.py
index 76c1695..8372efb 100644
--- a/src/zope/exceptions/__init__.py
+++ b/src/zope/exceptions/__init__.py
@@ -16,26 +16,33 @@
 These exceptions are so general purpose that they don't belong in Zope
 application-specific packages.
 """
-from zope.exceptions.interfaces import DuplicationError
-from zope.exceptions.interfaces import IDuplicationError
-from zope.exceptions.interfaces import UserError
-from zope.exceptions.interfaces import IUserError
 
-from zope.exceptions.exceptionformatter import format_exception
-from zope.exceptions.exceptionformatter import print_exception
-from zope.exceptions.exceptionformatter import extract_stack
+from zope.exceptions.interfaces import (  # noqa: F401
+    DuplicationError,
+    IDuplicationError,
+    UserError,
+    IUserError,
+)
+
+from zope.exceptions.exceptionformatter import (  # noqa: F401
+    format_exception,
+    print_exception,
+    extract_stack,
+)
 
 # avoid dependency on zope.security:
 try:
-    import zope.security
-except ImportError as v: #pragma: no cover
+    import zope.security  # noqa: F401
+except ImportError as v:  # pragma: no cover
     # "ImportError: No module named security"
     if 'security' not in str(v):
         raise
-else: #pragma: no cover
-    from zope.security.interfaces import IUnauthorized
-    from zope.security.interfaces import Unauthorized
-    from zope.security.interfaces import IForbidden
-    from zope.security.interfaces import IForbiddenAttribute
-    from zope.security.interfaces import Forbidden
-    from zope.security.interfaces import ForbiddenAttribute
+else:  # pragma: no cover
+    from zope.security.interfaces import (  # noqa: F401
+        IUnauthorized,
+        Unauthorized,
+        IForbidden,
+        IForbiddenAttribute,
+        Forbidden,
+        ForbiddenAttribute,
+    )
diff --git a/src/zope/exceptions/exceptionformatter.py b/src/zope/exceptions/exceptionformatter.py
index 47e0f41..7568a6e 100644
--- a/src/zope/exceptions/exceptionformatter.py
+++ b/src/zope/exceptions/exceptionformatter.py
@@ -92,7 +92,7 @@ class TextExceptionFormatter(object):
                 extra = getInfo()
                 if extra:
                     result.append(self.formatSupplementInfo(extra))
-            except: #pragma: no cover
+            except Exception:  # pragma: no cover
                 if DEBUG_EXCEPTION_FORMATTER:
                     traceback.print_exc()
                 # else just swallow the exception.
@@ -150,7 +150,7 @@ class TextExceptionFormatter(object):
             try:
                 supp = factory(*args)
                 result.extend(self.formatSupplement(supp, tb))
-            except: #pragma: no cover
+            except Exception:  # pragma: no cover
                 if DEBUG_EXCEPTION_FORMATTER:
                     traceback.print_exc()
                 # else just swallow the exception.
@@ -159,7 +159,7 @@ class TextExceptionFormatter(object):
             tbi = f_locals.get('__traceback_info__', None)
             if tbi is not None:
                 result.append(self.formatTracebackInfo(tbi))
-        except: #pragma: no cover
+        except Exception:  # pragma: no cover
             if DEBUG_EXCEPTION_FORMATTER:
                 traceback.print_exc()
             # else just swallow the exception.
@@ -175,7 +175,7 @@ class TextExceptionFormatter(object):
 
     def formatException(self, etype, value, tb):
         # The next line provides a way to detect recursion.
-        __exception_formatter__ = 1
+        __exception_formatter__ = 1  # noqa: F841
         result = []
         while tb is not None:
             if tb.tb_frame.f_locals.get('__exception_formatter__'):
@@ -207,7 +207,7 @@ class TextExceptionFormatter(object):
                 f = sys.exc_info()[2].tb_frame.f_back
 
         # The next line provides a way to detect recursion.
-        __exception_formatter__ = 1
+        __exception_formatter__ = 1  # noqa: F841
         result = []
         while f is not None:
             if f.f_locals.get('__exception_formatter__'):
@@ -250,10 +250,9 @@ class HTMLExceptionFormatter(TextExceptionFormatter):
                 s = str(s)
             except UnicodeError:
                 if hasattr(s, 'encode'):
-                    # We probably got a unicode string on
-                    # Python 2.
+                    # We probably got a unicode string on Python 2.
                     s = s.encode('utf-8')
-                else: # pragma: no cover
+                else:  # pragma: no cover
                     raise
         return escape(s, quote=False)
 
@@ -309,7 +308,7 @@ def print_exception(t, v, tb, limit=None, file=None, as_html=False,
     information to the traceback and accepts two options, 'as_html'
     and 'with_filenames'.
     """
-    if file is None: # pragma: no cover
+    if file is None:  # pragma: no cover
         file = sys.stderr
     lines = format_exception(t, v, tb, limit, as_html, with_filenames)
     for line in lines:
diff --git a/src/zope/exceptions/log.py b/src/zope/exceptions/log.py
index 574ccd3..657ea7b 100644
--- a/src/zope/exceptions/log.py
+++ b/src/zope/exceptions/log.py
@@ -21,6 +21,7 @@ from zope.exceptions.exceptionformatter import print_exception
 
 Buffer = io.StringIO if bytes is not str else io.BytesIO
 
+
 class Formatter(logging.Formatter):
 
     def formatException(self, ei):
diff --git a/src/zope/exceptions/tests/test_exceptionformatter.py b/src/zope/exceptions/tests/test_exceptionformatter.py
index 9046950..23afe12 100644
--- a/src/zope/exceptions/tests/test_exceptionformatter.py
+++ b/src/zope/exceptions/tests/test_exceptionformatter.py
@@ -121,13 +121,16 @@ class TextExceptionFormatterTests(unittest.TestCase):
     def test_formatSupplement_w_warnings(self):
         fmt = self._makeOne()
         supplement = DummySupplement()
-        supplement.warnings = ['Beware the ides of March!',
-                               'You\'re gonna get wasted.',
-                              ]
-        self.assertEqual(fmt.formatSupplement(supplement, tb=None),
-                         ['   - Warning: Beware the ides of March!',
-                          '   - Warning: You\'re gonna get wasted.',
-                         ])
+        supplement.warnings = [
+            'Beware the ides of March!',
+            'You\'re gonna get wasted.',
+        ]
+        self.assertEqual(
+            fmt.formatSupplement(supplement, tb=None),
+            [
+                '   - Warning: Beware the ides of March!',
+                '   - Warning: You\'re gonna get wasted.',
+            ])
 
     def test_formatSupplement_w_getInfo_empty(self):
         fmt = self._makeOne()
@@ -407,9 +410,10 @@ class TextExceptionFormatterTests(unittest.TestCase):
         expected = [
             '  File "dummy/filename.py", line 17, in dummy_function\n',
             '  File "dummy/filename.py", line 27, in dummy_function\n',
-            '(Recursive extractStack() stopped, trying traceback.format_stack)\n',
+            ('(Recursive extractStack() stopped,'
+             ' trying traceback.format_stack)\n'),
             '  Module dummy/filename.py, line 43, in dummy_function\n',
-            ]
+        ]
 
         self.assertEqual(expected, lines)
 
@@ -627,6 +631,7 @@ class Test_format_exception(unittest.TestCase):
     def test_multiple_levels(self):
         # Ensure many levels are shown in a traceback.
         HOW_MANY = 10
+
         def f(n):
             """Produces a (n + 1)-level traceback."""
             __traceback_info__ = 'level%d' % n
@@ -658,7 +663,8 @@ class Test_format_exception(unittest.TestCase):
             s = self._callFUT(False)
         lines = s.splitlines()[-3:]
         self.assertEqual(lines[0], '    syntax error')
-        self.assertTrue(lines[1].endswith('    ^')) #PyPy has a shorter prefix
+        # PyPy has a shorter prefix
+        self.assertTrue(lines[1].endswith('    ^'))
         self.assertEqual(lines[2], 'SyntaxError: invalid syntax')
 
     def test_traceback_info_non_ascii(self):
@@ -671,7 +677,6 @@ class Test_format_exception(unittest.TestCase):
         self.assertIsInstance(s, str)
         self.assertIn('Have a Snowman', s)
 
-
     def test_recursion_failure(self):
         from zope.exceptions.exceptionformatter import TextExceptionFormatter
 
@@ -711,13 +716,16 @@ class Test_format_exception(unittest.TestCase):
         expected = dedent("""\
             <p>Traceback (most recent call last):</p>
             <ul>
-            <li>  Module zope.exceptions.tests.test_exceptionformatter, line ABC, in test_format_exception_as_html<br />
+            <li>  Module {module}, line ABC, in {fn}<br />
                 exec('import')</li>
             </ul><p>  File "&lt;string&gt;", line 1<br />
                 import<br />
                      ^<br />
             SyntaxError: invalid syntax<br />
-            </p>""")
+            </p>""").format(
+                module='zope.exceptions.tests.test_exceptionformatter',
+                fn='test_format_exception_as_html',
+            )
         # HTML formatter uses Windows line endings for some reason.
         result = result.replace('\r\n', '\n')
         result = re.sub(r'line \d\d\d,', 'line ABC,', result)
@@ -856,6 +864,7 @@ class TestingTracebackSupplement(object):
     line = 634
     column = 57
     warnings = ['Repent, for the end is nigh']
+
     def __init__(self, expression):
         self.expression = expression
 
@@ -863,6 +872,7 @@ class TestingTracebackSupplement(object):
 class DummySupplement(object):
     def __init__(self, info=''):
         self._info = info
+
     def getInfo(self):
         return self._info
 
@@ -875,15 +885,18 @@ class DummyTB(object):
 class DummyFrame(object):
     f_lineno = 137
     f_back = None
+
     def __init__(self):
         self.f_locals = {}
         self.f_globals = {}
         self.f_code = DummyCode()
 
+
 class DummyCode(object):
     co_filename = 'dummy/filename.py'
     co_name = 'dummy_function'
 
+
 class _Monkey(object):
     # context-manager for replacing module names in the scope of a test.
     def __init__(self, module, **kw):
@@ -898,13 +911,11 @@ class _Monkey(object):
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         for key, value in self.to_restore.items():
-            if value is not self: # pragma: no cover
+            if value is not self:  # pragma: no cover
                 setattr(self.module, key, value)
             else:
                 delattr(self.module, key)
 
 
-
-
 def test_suite():
     return unittest.defaultTestLoader.loadTestsFromName(__name__)
diff --git a/src/zope/exceptions/tests/test_log.py b/src/zope/exceptions/tests/test_log.py
index 9e01eea..35c78f2 100644
--- a/src/zope/exceptions/tests/test_log.py
+++ b/src/zope/exceptions/tests/test_log.py
@@ -36,9 +36,8 @@ class FormatterTests(unittest.TestCase):
         self.assertEqual(lines[0], 'Traceback (most recent call last):')
         self.assertEqual(lines[1], '  File "dummy/filename.py", line 14, '
                                    'in dummy_function')
-        self.assertEqual(lines[2],
-                         traceback.format_exception_only(
-                             ValueError, exc)[0][:-1]) #trailing \n
+        emsg = traceback.format_exception_only(ValueError, exc)[0]
+        self.assertEqual(lines[2], emsg[:-1])  # strip trailing \n from emsg
 
     def test_unicode_traceback_info(self):
         import traceback
@@ -58,11 +57,10 @@ class FormatterTests(unittest.TestCase):
         # utf-8 encoded on Python 2, unicode on Python 3
         expected += '\xe2\x98\x83' if bytes is str else u'\u2603'
 
-        self.assertEqual(lines[2],
-                         expected)
-        self.assertEqual(lines[3],
-                         traceback.format_exception_only(
-                             ValueError, exc)[0][:-1]) #trailing \n
+        self.assertEqual(lines[2], expected)
+
+        emsg = traceback.format_exception_only(ValueError, exc)[0]
+        self.assertEqual(lines[3], emsg[:-1])  # strip trailing \n from emsg
 
 
 class DummyTB(object):
@@ -72,14 +70,17 @@ class DummyTB(object):
     def __init__(self):
         self.tb_frame = DummyFrame()
 
+
 class DummyFrame(object):
     f_lineno = 137
     f_back = None
+
     def __init__(self):
         self.f_locals = {}
         self.f_globals = {}
         self.f_code = DummyCode()
 
+
 class DummyCode(object):
     co_filename = 'dummy/filename.py'
     co_name = 'dummy_function'
diff --git a/tox.ini b/tox.ini
index 071807e..61d430e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,3 +27,10 @@ basepython =
 commands =
     sphinx-build -b html -d docs/_build/doctrees docs docs/_build/html
     sphinx-build -b doctest -d docs/_build/doctrees docs docs/_build/doctest
+
+[testenv:flake8]
+skip_install = true
+deps =
+    flake8
+commands =
+    flake8 src/ setup.py