Merge branch 'master' into more_implicit_cls_methods

Author: cooperlees

README.rst

@@ -90,6 +90,9 @@ ahead of time.
 property access: ``x.attr = val``. There is no additional safety in
 using ``setattr`` if you know the attribute name ahead of time.
 
+**B011**: Do not call `assert False` since `python -O` removes these calls.
+Instead callers should `raise AssertionError()`.
+
 
 Python 3 compatibility warnings
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -233,6 +236,12 @@ MIT
 Change Log
 ----------
 
+19.3.0
+~~~~~~
+
+* For B902, the first argument for metaclass class methods can be
+  "mcs", matching the name preferred by PyCharm.
+
 18.2.0
 ~~~~~~
 

bugbear.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python3
 import ast
 from collections import namedtuple
 from contextlib import suppress
@@ -208,6 +207,10 @@ def visit_For(self, node):
         self.check_for_b007(node)
         self.generic_visit(node)
 
+    def visit_Assert(self, node):
+        self.check_for_b011(node)
+        self.generic_visit(node)
+
     def visit_AsyncFunctionDef(self, node):
         self.check_for_b902(node)
         self.check_for_b006(node)
@@ -273,6 +276,10 @@ def check_for_b007(self, node):
             n = targets.names[name][0]
             self.errors.append(B007(n.lineno, n.col_offset, vars=(name,)))
 
+    def check_for_b011(self, node):
+        if isinstance(node.test, ast.NameConstant) and node.test.value is False:
+            self.errors.append(B011(node.lineno, node.col_offset))
+
     def check_for_b901(self, node):
         xs = list(node.body)
         has_yield = False
@@ -494,6 +501,10 @@ def visit(self, node):
     message="B010 Do not call setattr with a constant attribute value, "
     "it is not any safer than normal property access."
 )
+B011 = Error(
+    message="B011 Do not call assert False since python -O removes these calls. "
+            "Instead callers should raise AssertionError()."
+)
 
 
 # Those could be false positives but it's more dangerous to let them slip
@@ -552,7 +563,7 @@ def visit(self, node):
 B902.implicit_classmethods = {"__new__", "__init_subclass__", "__class_getitem__"}
 B902.self = ["self"]  # it's a list because the first is preferred
 B902.cls = ["cls", "klass"]  # ditto.
-B902.metacls = ["metacls", "metaclass", "typ"]  # ditto.
+B902.metacls = ["metacls", "metaclass", "typ", "mcs"]  # ditto.
 
 B903 = Error(
     message="B903 Data class should either be immutable or use __slots__ to "

tests/b011.py

@@ -0,0 +1,10 @@
+"""
+Should emit:
+B011 - on line 8
+B011 - on line 10
+"""
+
+assert 1 != 2
+assert False
+assert 1 != 2, "message"
+assert False, "message"

tests/b902.py

@@ -72,6 +72,10 @@ def __init__(self, name, bases, d):
     def __prepare__(cls, name, bases):
         return {}
 
+    @classmethod
+    def first_arg_mcs_allowed(mcs, value):
+        ...
+
 
 def type_factory():
     return object
@@ -95,4 +99,4 @@ def __init_subclass__(cls, *args, **kwargs):
         ...
 
     def __class_getitem__(cls, key):
-        ...
+        ...

tests/test_bugbear.py

@@ -14,6 +14,7 @@
     B008,
     B009,
     B010,
+    B011,
     B301,
     B302,
     B303,
@@ -110,6 +111,15 @@ def test_b009_b010(self):
         errors = list(bbc.run())
         self.assertEqual(errors, self.errors(B009(15, 0), B010(22, 0)))
 
+    def test_b011(self):
+        filename = Path(__file__).absolute().parent / 'b011.py'
+        bbc = BugBearChecker(filename=str(filename))
+        errors = list(bbc.run())
+        self.assertEqual(
+            errors,
+            self.errors(B011(8, 0, vars=('i',)), B011(10, 0, vars=('k',))),
+        )
+
     def test_b301_b302_b305(self):
         filename = Path(__file__).absolute().parent / "b301_b302_b305.py"
         bbc = BugBearChecker(filename=str(filename))