unidiomatic-typecheck is no longer emitted for in and ``not i…

…n`` operators

The original use case for this check was to catch old style type checking idioms
such as `type(x) is ...`, but it should not have been extended to handle `in` operators
as well.

Close #3337

ChangeLog

@@ -26,6 +26,10 @@ Release date: TBA
 
 * Positional-only arguments are taken in account for ``useless-super-delegation``
 
+* ``unidiomatic-typecheck`` is no longer emitted for ``in`` and ``not in`` operators
+
+  Close #3337
+
 * Positional-only argument annotations are taken in account for ``unused-import``
 
   Close #3462

pylint/checkers/base.py

@@ -152,7 +152,7 @@ def get_regex(cls, name_type):
 REVERSED_PROTOCOL_METHOD = "__reversed__"
 SEQUENCE_PROTOCOL_METHODS = ("__getitem__", "__len__")
 REVERSED_METHODS = (SEQUENCE_PROTOCOL_METHODS, (REVERSED_PROTOCOL_METHOD,))
-TYPECHECK_COMPARISON_OPERATORS = frozenset(("is", "is not", "==", "!=", "in", "not in"))
+TYPECHECK_COMPARISON_OPERATORS = frozenset(("is", "is not", "==", "!="))
 LITERAL_NODE_TYPES = (astroid.Const, astroid.Dict, astroid.List, astroid.Set)
 UNITTEST_CASE = "unittest.case"
 BUILTINS = builtins.__name__

tests/functional/u/unidiomatic_typecheck.py

@@ -6,25 +6,19 @@ def simple_positives():
     type(42) is not int # [unidiomatic-typecheck]
     type(42) == int # [unidiomatic-typecheck]
     type(42) != int # [unidiomatic-typecheck]
-    type(42) in [int] # [unidiomatic-typecheck]
-    type(42) not in [int] # [unidiomatic-typecheck]
 
 def simple_inference_positives():
     alias = type
     alias(42) is int # [unidiomatic-typecheck]
     alias(42) is not int # [unidiomatic-typecheck]
     alias(42) == int # [unidiomatic-typecheck]
     alias(42) != int # [unidiomatic-typecheck]
-    alias(42) in [int] # [unidiomatic-typecheck]
-    alias(42) not in [int] # [unidiomatic-typecheck]
 
 def type_creation_negatives():
     type('Q', (object,), dict(a=1)) is int
     type('Q', (object,), dict(a=1)) is not int
     type('Q', (object,), dict(a=1)) == int
     type('Q', (object,), dict(a=1)) != int
-    type('Q', (object,), dict(a=1)) in [int]
-    type('Q', (object,), dict(a=1)) not in [int]
 
 def invalid_type_call_negatives(**kwargs):
     type(bad=7) is int

tests/functional/u/unidiomatic_typecheck.txt

@@ -3,16 +3,13 @@ unidiomatic-typecheck:6:simple_positives:Using type() instead of isinstance() fo
 unidiomatic-typecheck:7:simple_positives:Using type() instead of isinstance() for a typecheck.
 unidiomatic-typecheck:8:simple_positives:Using type() instead of isinstance() for a typecheck.
 unidiomatic-typecheck:9:simple_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:10:simple_positives:Using type() instead of isinstance() for a typecheck.
+unidiomatic-typecheck:12:simple_inference_positives:Using type() instead of isinstance() for a typecheck.
+unidiomatic-typecheck:13:simple_inference_positives:Using type() instead of isinstance() for a typecheck.
 unidiomatic-typecheck:14:simple_inference_positives:Using type() instead of isinstance() for a typecheck.
 unidiomatic-typecheck:15:simple_inference_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:16:simple_inference_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:17:simple_inference_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:18:simple_inference_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:19:simple_inference_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:71:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:72:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:73:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:74:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:75:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
-unidiomatic-typecheck:76:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
+unidiomatic-typecheck:65:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
+unidiomatic-typecheck:66:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
+unidiomatic-typecheck:67:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
+unidiomatic-typecheck:68:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
+unidiomatic-typecheck:69:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.
+unidiomatic-typecheck:70:type_of_literals_positives:Using type() instead of isinstance() for a typecheck.