Format code with black.

21 files changed, 80 insertions, 79 deletions

diff --git a/README.rst b/README.rst
index 732e26f..5370b34 100644
--- a/README.rst
+++ b/README.rst
@@ -25,6 +25,10 @@ cachetools
    :target: https://raw.github.com/tkem/cachetools/master/LICENSE
    :alt: License
 
+.. image:: https://img.shields.io/badge/code%20style-black-000000.svg
+   :target: https://github.com/psf/black
+   :alt: Code style: black
+
 This module provides various memoizing collections and decorators,
 including variants of the Python Standard Library's `@lru_cache`_
 function decorator.
diff --git a/cachetools/__init__.py b/cachetools/__init__.py
index 2e66e20..1c925cc 100644
--- a/cachetools/__init__.py
+++ b/cachetools/__init__.py
@@ -10,15 +10,15 @@ from .rr import RRCache
 from .ttl import TTLCache
 
 __all__ = (
-    'Cache',
-    'FIFOCache',
-    'LFUCache',
-    'LRUCache',
-    'MRUCache',
-    'RRCache',
-    'TTLCache',
-    'cached',
-    'cachedmethod'
+    "Cache",
+    "FIFOCache",
+    "LFUCache",
+    "LRUCache",
+    "MRUCache",
+    "RRCache",
+    "TTLCache",
+    "cached",
+    "cachedmethod",
 )
 
-__version__ = '4.2.1'
+__version__ = "4.2.1"
diff --git a/cachetools/cache.py b/cachetools/cache.py
index ed3d268..0c81d06 100644
--- a/cachetools/cache.py
+++ b/cachetools/cache.py
@@ -32,7 +32,7 @@ class Cache(MutableMapping):
         self.__maxsize = maxsize
 
     def __repr__(self):
-        return '%s(%r, maxsize=%r, currsize=%r)' % (
+        return "%s(%r, maxsize=%r, currsize=%r)" % (
             self.__class__.__name__,
             list(self.__data.items()),
             self.__maxsize,
@@ -49,7 +49,7 @@ class Cache(MutableMapping):
         maxsize = self.__maxsize
         size = self.getsizeof(value)
         if size > maxsize:
-            raise ValueError('value too large')
+            raise ValueError("value too large")
         if key not in self.__data or self.__size[key] < size:
             while self.__currsize + size > maxsize:
                 self.popitem()
diff --git a/cachetools/decorators.py b/cachetools/decorators.py
index 217b9a8..3e78603 100644
--- a/cachetools/decorators.py
+++ b/cachetools/decorators.py
@@ -8,11 +8,15 @@ def cached(cache, key=hashkey, lock=None):
     results in a cache.
 
     """
+
     def decorator(func):
         if cache is None:
+
             def wrapper(*args, **kwargs):
                 return func(*args, **kwargs)
+
         elif lock is None:
+
             def wrapper(*args, **kwargs):
                 k = key(*args, **kwargs)
                 try:
@@ -25,7 +29,9 @@ def cached(cache, key=hashkey, lock=None):
                 except ValueError:
                     pass  # value too large
                 return v
+
         else:
+
             def wrapper(*args, **kwargs):
                 k = key(*args, **kwargs)
                 try:
@@ -40,7 +46,9 @@ def cached(cache, key=hashkey, lock=None):
                         return cache.setdefault(k, v)
                 except ValueError:
                     return v  # value too large
+
         return functools.update_wrapper(wrapper, func)
+
     return decorator
 
 
@@ -49,8 +57,10 @@ def cachedmethod(cache, key=hashkey, lock=None):
     callable that saves results in a cache.
 
     """
+
     def decorator(method):
         if lock is None:
+
             def wrapper(self, *args, **kwargs):
                 c = cache(self)
                 if c is None:
@@ -66,7 +76,9 @@ def cachedmethod(cache, key=hashkey, lock=None):
                 except ValueError:
                     pass  # value too large
                 return v
+
         else:
+
             def wrapper(self, *args, **kwargs):
                 c = cache(self)
                 if c is None:
@@ -84,5 +96,7 @@ def cachedmethod(cache, key=hashkey, lock=None):
                         return c.setdefault(k, v)
                 except ValueError:
                     return v  # value too large
+
         return functools.update_wrapper(wrapper, method)
+
     return decorator
diff --git a/cachetools/fifo.py b/cachetools/fifo.py
index 9f254f1..e7c377e 100644
--- a/cachetools/fifo.py
+++ b/cachetools/fifo.py
@@ -26,6 +26,6 @@ class FIFOCache(Cache):
         try:
             key = next(iter(self.__order))
         except StopIteration:
-            raise KeyError('%s is empty' % type(self).__name__) from None
+            raise KeyError("%s is empty" % type(self).__name__) from None
         else:
             return (key, self.pop(key))
diff --git a/cachetools/func.py b/cachetools/func.py
index 2be517e..57fb72d 100644
--- a/cachetools/func.py
+++ b/cachetools/func.py
@@ -19,16 +19,15 @@ from .mru import MRUCache
 from .rr import RRCache
 from .ttl import TTLCache
 
-__all__ = ('lfu_cache', 'lru_cache', 'mru_cache', 'rr_cache', 'ttl_cache')
+__all__ = ("lfu_cache", "lru_cache", "mru_cache", "rr_cache", "ttl_cache")
 
 
-_CacheInfo = collections.namedtuple('CacheInfo', [
-    'hits', 'misses', 'maxsize', 'currsize'
-])
+_CacheInfo = collections.namedtuple(
+    "CacheInfo", ["hits", "misses", "maxsize", "currsize"]
+)
 
 
 class _UnboundCache(dict):
-
     @property
     def maxsize(self):
         return None
@@ -88,9 +87,10 @@ def _cache(cache, typed):
 
         wrapper.cache_info = cache_info
         wrapper.cache_clear = cache_clear
-        wrapper.cache_parameters = lambda: {'maxsize': maxsize, 'typed': typed}
+        wrapper.cache_parameters = lambda: {"maxsize": maxsize, "typed": typed}
         functools.update_wrapper(wrapper, func)
         return wrapper
+
     return decorator
 
 
diff --git a/cachetools/keys.py b/cachetools/keys.py
index 355d742..13630a4 100644
--- a/cachetools/keys.py
+++ b/cachetools/keys.py
@@ -1,6 +1,6 @@
 """Key functions for memoizing decorators."""
 
-__all__ = ('hashkey', 'typedkey')
+__all__ = ("hashkey", "typedkey")
 
 
 class _HashedTuple(tuple):
diff --git a/cachetools/lfu.py b/cachetools/lfu.py
index 894a326..6289b5c 100644
--- a/cachetools/lfu.py
+++ b/cachetools/lfu.py
@@ -27,8 +27,8 @@ class LFUCache(Cache):
     def popitem(self):
         """Remove and return the `(key, value)` pair least frequently used."""
         try:
-            (key, _), = self.__counter.most_common(1)
+            ((key, _),) = self.__counter.most_common(1)
         except ValueError:
-            raise KeyError('%s is empty' % type(self).__name__) from None
+            raise KeyError("%s is empty" % type(self).__name__) from None
         else:
             return (key, self.pop(key))
diff --git a/cachetools/lru.py b/cachetools/lru.py
index 33749d1..dbbe787 100644
--- a/cachetools/lru.py
+++ b/cachetools/lru.py
@@ -29,7 +29,7 @@ class LRUCache(Cache):
         try:
             key = next(iter(self.__order))
         except StopIteration:
-            raise KeyError('%s is empty' % type(self).__name__) from None
+            raise KeyError("%s is empty" % type(self).__name__) from None
         else:
             return (key, self.pop(key))
 
diff --git a/cachetools/mru.py b/cachetools/mru.py
index 41e2aa1..92ec6db 100644
--- a/cachetools/mru.py
+++ b/cachetools/mru.py
@@ -29,7 +29,7 @@ class MRUCache(Cache):
         try:
             key = next(iter(self.__order))
         except StopIteration:
-            raise KeyError('%s is empty' % type(self).__name__) from None
+            raise KeyError("%s is empty" % type(self).__name__) from None
         else:
             return (key, self.pop(key))
 
diff --git a/cachetools/rr.py b/cachetools/rr.py
index 5b47e87..561dbe5 100644
--- a/cachetools/rr.py
+++ b/cachetools/rr.py
@@ -29,6 +29,6 @@ class RRCache(Cache):
         try:
             key = self.__choice(list(self))
         except IndexError:
-            raise KeyError('%s is empty' % type(self).__name__) from None
+            raise KeyError("%s is empty" % type(self).__name__) from None
         else:
             return (key, self.pop(key))
diff --git a/cachetools/ttl.py b/cachetools/ttl.py
index 528a085..72f6d52 100644
--- a/cachetools/ttl.py
+++ b/cachetools/ttl.py
@@ -6,7 +6,7 @@ from .cache import Cache
 
 class _Link(object):
 
-    __slots__ = ('key', 'expire', 'next', 'prev')
+    __slots__ = ("key", "expire", "next", "prev")
 
     def __init__(self, key=None, expire=None):
         self.key = key
@@ -23,7 +23,6 @@ class _Link(object):
 
 
 class _Timer(object):
-
     def __init__(self, timer):
         self.__timer = timer
         self.__nesting = 0
@@ -198,7 +197,7 @@ class TTLCache(Cache):
             try:
                 key = next(iter(self.__links))
             except StopIteration:
-                raise KeyError('%s is empty' % type(self).__name__) from None
+                raise KeyError("%s is empty" % type(self).__name__) from None
             else:
                 return (key, self.pop(key))
 
diff --git a/docs/conf.py b/docs/conf.py
index 9efbd40..f55e5a5 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -8,17 +8,17 @@ def get_version():
     return cp["metadata"]["version"]
 
 
-project = 'cachetools'
-copyright = '2014-2021 Thomas Kemmer'
+project = "cachetools"
+copyright = "2014-2021 Thomas Kemmer"
 version = get_version()
 release = version
 
 extensions = [
-    'sphinx.ext.autodoc',
-    'sphinx.ext.coverage',
-    'sphinx.ext.doctest',
-    'sphinx.ext.todo'
+    "sphinx.ext.autodoc",
+    "sphinx.ext.coverage",
+    "sphinx.ext.doctest",
+    "sphinx.ext.todo",
 ]
-exclude_patterns = ['_build']
-master_doc = 'index'
-html_theme = 'default'
+exclude_patterns = ["_build"]
+master_doc = "index"
+html_theme = "default"
diff --git a/setup.cfg b/setup.cfg
index 5e40883..bd7fb73 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -33,7 +33,10 @@ exclude =
     tests.*
 
 [flake8]
-exclude = .git, .tox
+max-line-length = 80
+exclude = .git, .tox, build
+select = C, E, F, W, B, B950, I, N
+ignore = E501, W503
 
 [build_sphinx]
 source-dir = docs/
diff --git a/tests/__init__.py b/tests/__init__.py
index 70a0f03..bfd5ec6 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -12,7 +12,7 @@ class CacheTestMixin(object):
         self.assertEqual(1, cache.maxsize)
         self.assertEqual(0, cache.currsize)
         self.assertEqual(1, cache.getsizeof(None))
-        self.assertEqual(1, cache.getsizeof(''))
+        self.assertEqual(1, cache.getsizeof(""))
         self.assertEqual(1, cache.getsizeof(0))
         self.assertTrue(repr(cache).startswith(cache.__class__.__name__))
 
@@ -47,10 +47,10 @@ class CacheTestMixin(object):
         self.assertEqual(1, cache[1])
         self.assertEqual(2, cache[2])
 
-        cache.update({1: 'a', 2: 'b'})
+        cache.update({1: "a", 2: "b"})
         self.assertEqual(2, len(cache))
-        self.assertEqual('a', cache[1])
-        self.assertEqual('b', cache[2])
+        self.assertEqual("a", cache[1])
+        self.assertEqual("b", cache[2])
 
     def test_delete(self):
         cache = self.Cache(maxsize=2)
@@ -108,7 +108,7 @@ class CacheTestMixin(object):
         with self.assertRaises(KeyError):
             cache.popitem()
 
-    @unittest.skipUnless(sys.version_info >= (3, 7), 'requires Python 3.7')
+    @unittest.skipUnless(sys.version_info >= (3, 7), "requires Python 3.7")
     def test_popitem_exception_context(self):
         # since Python 3.7, MutableMapping.popitem() suppresses
         # exception context as implementation detail
diff --git a/tests/test_func.py b/tests/test_func.py
index 39dce77..721d5a6 100644
--- a/tests/test_func.py
+++ b/tests/test_func.py
@@ -4,15 +4,12 @@ import cachetools.func
 
 
 class DecoratorTestMixin(object):
-
     def decorator(self, maxsize, **kwargs):
         return self.DECORATOR(maxsize, **kwargs)
 
     def test_decorator(self):
         cached = self.decorator(maxsize=2)(lambda n: n)
-        self.assertEqual(cached.cache_parameters(), {
-            'maxsize': 2, 'typed': False
-        })
+        self.assertEqual(cached.cache_parameters(), {"maxsize": 2, "typed": False})
         self.assertEqual(cached.cache_info(), (0, 0, 2, 0))
         self.assertEqual(cached(1), 1)
         self.assertEqual(cached.cache_info(), (0, 1, 2, 1))
@@ -23,9 +20,7 @@ class DecoratorTestMixin(object):
 
     def test_decorator_clear(self):
         cached = self.decorator(maxsize=2)(lambda n: n)
-        self.assertEqual(cached.cache_parameters(), {
-            'maxsize': 2, 'typed': False
-        })
+        self.assertEqual(cached.cache_parameters(), {"maxsize": 2, "typed": False})
         self.assertEqual(cached.cache_info(), (0, 0, 2, 0))
         self.assertEqual(cached(1), 1)
         self.assertEqual(cached.cache_info(), (0, 1, 2, 1))
@@ -36,9 +31,7 @@ class DecoratorTestMixin(object):
 
     def test_decorator_nocache(self):
         cached = self.decorator(maxsize=0)(lambda n: n)
-        self.assertEqual(cached.cache_parameters(), {
-            'maxsize': 0, 'typed': False
-        })
+        self.assertEqual(cached.cache_parameters(), {"maxsize": 0, "typed": False})
         self.assertEqual(cached.cache_info(), (0, 0, 0, 0))
         self.assertEqual(cached(1), 1)
         self.assertEqual(cached.cache_info(), (0, 1, 0, 0))
@@ -49,9 +42,7 @@ class DecoratorTestMixin(object):
 
     def test_decorator_unbound(self):
         cached = self.decorator(maxsize=None)(lambda n: n)
-        self.assertEqual(cached.cache_parameters(), {
-            'maxsize': None, 'typed': False
-        })
+        self.assertEqual(cached.cache_parameters(), {"maxsize": None, "typed": False})
         self.assertEqual(cached.cache_info(), (0, 0, None, 0))
         self.assertEqual(cached(1), 1)
         self.assertEqual(cached.cache_info(), (0, 1, None, 1))
@@ -62,9 +53,7 @@ class DecoratorTestMixin(object):
 
     def test_decorator_typed(self):
         cached = self.decorator(maxsize=2, typed=True)(lambda n: n)
-        self.assertEqual(cached.cache_parameters(), {
-            'maxsize': 2, 'typed': True
-        })
+        self.assertEqual(cached.cache_parameters(), {"maxsize": 2, "typed": True})
         self.assertEqual(cached.cache_info(), (0, 0, 2, 0))
         self.assertEqual(cached(1), 1)
         self.assertEqual(cached.cache_info(), (0, 1, 2, 1))
@@ -77,9 +66,7 @@ class DecoratorTestMixin(object):
 
     def test_decorator_user_function(self):
         cached = self.decorator(lambda n: n)
-        self.assertEqual(cached.cache_parameters(), {
-            'maxsize': 128, 'typed': False
-        })
+        self.assertEqual(cached.cache_parameters(), {"maxsize": 128, "typed": False})
         self.assertEqual(cached.cache_info(), (0, 0, 128, 0))
         self.assertEqual(cached(1), 1)
         self.assertEqual(cached.cache_info(), (0, 1, 128, 1))
diff --git a/tests/test_keys.py b/tests/test_keys.py
index 8137704..892a620 100644
--- a/tests/test_keys.py
+++ b/tests/test_keys.py
@@ -4,7 +4,6 @@ import cachetools.keys
 
 
 class CacheKeysTest(unittest.TestCase):
-
     def test_hashkey(self, key=cachetools.keys.hashkey):
         self.assertEqual(key(), key())
         self.assertEqual(hash(key()), hash(key()))
@@ -47,7 +46,7 @@ class CacheKeysTest(unittest.TestCase):
     def test_pickle(self, key=cachetools.keys.hashkey):
         import pickle
 
-        for k in [key(), key('abc'), key('abc', 123), key('abc', q='abc')]:
+        for k in [key(), key("abc"), key("abc", 123), key("abc", q="abc")]:
             # white-box test: assert cached hash value is not pickled
             self.assertEqual(len(k.__dict__), 0)
             h = hash(k)
diff --git a/tests/test_method.py b/tests/test_method.py
index 9252fef..235eca4 100644
--- a/tests/test_method.py
+++ b/tests/test_method.py
@@ -5,18 +5,17 @@ from cachetools import LRUCache, cachedmethod, keys
 
 
 class Cached(object):
-
     def __init__(self, cache, count=0):
         self.cache = cache
         self.count = count
 
-    @cachedmethod(operator.attrgetter('cache'))
+    @cachedmethod(operator.attrgetter("cache"))
     def get(self, value):
         count = self.count
         self.count += 1
         return count
 
-    @cachedmethod(operator.attrgetter('cache'), key=keys.typedkey)
+    @cachedmethod(operator.attrgetter("cache"), key=keys.typedkey)
     def get_typed(self, value):
         count = self.count
         self.count += 1
@@ -24,16 +23,15 @@ class Cached(object):
 
     # https://github.com/tkem/cachetools/issues/107
     def __hash__(self):
-        raise TypeError('unhashable type')
+        raise TypeError("unhashable type")
 
 
 class Locked(object):
-
     def __init__(self, cache):
         self.cache = cache
         self.count = 0
 
-    @cachedmethod(operator.attrgetter('cache'), lock=lambda self: self)
+    @cachedmethod(operator.attrgetter("cache"), lock=lambda self: self)
     def get(self, value):
         return self.count
 
@@ -45,7 +43,6 @@ class Locked(object):
 
 
 class CachedMethodTest(unittest.TestCase):
-
     def test_dict(self):
         cached = Cached({})
 
diff --git a/tests/test_mru.py b/tests/test_mru.py
index 3a9f4d3..d11dba4 100644
--- a/tests/test_mru.py
+++ b/tests/test_mru.py
@@ -17,7 +17,7 @@ class MRUCacheTest(unittest.TestCase, CacheTestMixin):
         cache[3] = 3  # Evicts 1 because nothing's been used yet
 
         assert len(cache) == 2
-        assert 1 not in cache, 'Wrong key was evicted. Should have been `1`.'
+        assert 1 not in cache, "Wrong key was evicted. Should have been '1'."
         assert 2 in cache
         assert 3 in cache
 
@@ -29,7 +29,7 @@ class MRUCacheTest(unittest.TestCase, CacheTestMixin):
         cache[1]
         cache[2]
         cache[3] = 3  # Evicts 2
-        assert 2 not in cache, 'Wrong key was evicted. Should have been `2`.'
+        assert 2 not in cache, "Wrong key was evicted. Should have been '2'."
         assert 1 in cache
         assert 3 in cache
 
diff --git a/tests/test_wrapper.py b/tests/test_wrapper.py
index a6e649c..e154ff8 100644
--- a/tests/test_wrapper.py
+++ b/tests/test_wrapper.py
@@ -5,12 +5,11 @@ import cachetools.keys
 
 
 class DecoratorTestMixin(object):
-
     def cache(self, minsize):
         raise NotImplementedError
 
     def func(self, *args, **kwargs):
-        if hasattr(self, 'count'):
+        if hasattr(self, "count"):
             self.count += 1
         else:
             self.count = 0
@@ -101,7 +100,6 @@ class DecoratorTestMixin(object):
 
 
 class CacheWrapperTest(unittest.TestCase, DecoratorTestMixin):
-
     def cache(self, minsize):
         return cachetools.Cache(maxsize=minsize)
 
@@ -138,13 +136,11 @@ class CacheWrapperTest(unittest.TestCase, DecoratorTestMixin):
 
 
 class DictWrapperTest(unittest.TestCase, DecoratorTestMixin):
-
     def cache(self, minsize):
         return dict()
 
 
 class NoneWrapperTest(unittest.TestCase):
-
     def func(self, *args, **kwargs):
         return args + tuple(kwargs.items())
 
@@ -154,4 +150,4 @@ class NoneWrapperTest(unittest.TestCase):
 
         self.assertEqual(wrapper(0), (0,))
         self.assertEqual(wrapper(1), (1,))
-        self.assertEqual(wrapper(1, foo='bar'), (1, ('foo', 'bar')))
+        self.assertEqual(wrapper(1, foo="bar"), (1, ("foo", "bar")))
diff --git a/tox.ini b/tox.ini
index 2ae20e1..e2315db 100644
--- a/tox.ini
+++ b/tox.ini
@@ -31,6 +31,8 @@ commands =
 [testenv:flake8]
 deps =
     flake8
+    flake8-black; python_version >= "3.6" and implementation_name == "cpython"
+    flake8-bugbear
     flake8-import-order
 commands =
     flake8