Exclude types.MappingProxyType() from B008 (#144)

* Exclude types.MappingProxyType() from B008

* Update README.rst

README.rst

@@ -253,6 +253,7 @@ Next version
 ~~~~~~~~~~~~
 
 * Introduce B016 to check for raising a literal. (#141)
+* Exclude types.MappingProxyType() from B008. (#144)
 
 20.1.4
 ~~~~~~

bugbear.py

@@ -632,7 +632,12 @@ def visit(self, node):
         "use that variable as a default value."
     )
 )
-B008.immutable_calls = {"tuple", "frozenset"}
+B008.immutable_calls = {
+    "tuple",
+    "frozenset",
+    "types.MappingProxyType",
+    "MappingProxyType",
+}
 B009 = Error(
     message=(
         "B009 Do not call getattr with a constant attribute value, "

tests/b006_b008.py

@@ -1,6 +1,8 @@
 import collections
 import logging
 import time
+import types
+from types import MappingProxyType
 
 
 def this_is_okay(value=(1, 2, 3)):
@@ -11,6 +13,16 @@ def and_this_also(value=tuple()):
     pass
 
 
+def frozenset_also_okay(value=frozenset()):
+    pass
+
+
+def mappingproxytype_okay(
+    value=MappingProxyType({}), value2=types.MappingProxyType({})
+):
+    pass
+
+
 def this_is_wrong(value=[1, 2, 3]):
     ...
 

tests/test_bugbear.py

@@ -97,13 +97,13 @@ def test_b006_b008(self):
         self.assertEqual(
             errors,
             self.errors(
-                B006(14, 24),
-                B006(18, 29),
-                B006(22, 19),
-                B006(26, 19),
-                B006(30, 31),
-                B008(39, 38),
-                B006(55, 32),
+                B006(26, 24),
+                B006(30, 29),
+                B006(34, 19),
+                B006(38, 19),
+                B006(42, 31),
+                B008(51, 38),
+                B006(67, 32),
             ),
         )