Extended consider-using-tuple check to cover 'in' comparisons

Author: cdce8p

ChangeLog

@@ -3,21 +3,20 @@ Pylint's ChangeLog
 ------------------
 
 
-
 What's New in Pylint 2.10.0?
 ============================
 Release date: TBA
 
-* Added ``ignored-parents`` option to the design checker to ignore specific
-  classes from the ``too-many-ancestors`` check (R0901).
-
-  Partially closes #3057
-
 ..
   Put new features here and also in 'doc/whatsnew/2.10.rst'
 ..
   Put bug fixes that should not wait for a new minor version here
 
+* Added ``ignored-parents`` option to the design checker to ignore specific
+  classes from the ``too-many-ancestors`` check (R0901).
+
+  Partially closes #3057
+
 * Added ``unspecified-encoding``: Emitted when open() is called without specifying an encoding
 
   Closes #3826
@@ -37,13 +36,14 @@ Release date: TBA
 
   Closes #3878
 
+* ``CodeStyleChecker``:
+  * Extended ``consider-using-tuple`` check to cover ``in`` comparisons.
 
 
 What's New in Pylint 2.9.6?
 ===========================
 Release date: 2021-07-28
 
-
 * Fix a false positive ``undefined-variable`` when variable name in decoration
   matches function argument
 

doc/whatsnew/2.10.rst

@@ -17,10 +17,16 @@ New checkers
   Closes #3826
 
 
+Extensions
+==========
+
+* ``CodeStyleChecker``:
+  * Extended ``consider-using-tuple`` check to cover ``in`` comparisons.
+
+
 Other Changes
 =============
 
-
 * Performance of the Similarity checker has been improved.
 
 * Added ``time.clock`` to deprecated functions/methods for python 3.3

pylint/extensions/code_style.py

@@ -1,4 +1,4 @@
-from typing import List, Set, Tuple, Type, Union
+from typing import List, Set, Tuple, Type
 
 import astroid
 from astroid.node_classes import NodeNG
@@ -53,11 +53,18 @@ def visit_dict(self, node: astroid.Dict) -> None:
 
     @check_messages("consider-using-tuple")
     def visit_for(self, node: astroid.For) -> None:
-        self._check_inplace_defined_list_set(node)
+        self._check_inplace_defined_list_set(node.iter)
 
     @check_messages("consider-using-tuple")
     def visit_comprehension(self, node: astroid.Comprehension) -> None:
-        self._check_inplace_defined_list_set(node)
+        self._check_inplace_defined_list_set(node.iter)
+
+    @check_messages("consider-using-tuple")
+    def visit_compare(self, node: astroid.Compare) -> None:
+        for op, comparator in node.ops:
+            if op != "in":
+                continue
+            self._check_inplace_defined_list_set(comparator)
 
     def _check_dict_consider_namedtuple_dataclass(self, node: astroid.Dict) -> None:
         """Check if dictionary values can be replaced by Namedtuple or Dataclass."""
@@ -128,17 +135,15 @@ def _check_dict_consider_namedtuple_dataclass(self, node: astroid.Dict) -> None:
             self.add_message("consider-using-namedtuple-or-dataclass", node=node)
             return
 
-    def _check_inplace_defined_list_set(
-        self, node: Union[astroid.For, astroid.Comprehension]
-    ) -> None:
+    def _check_inplace_defined_list_set(self, node: NodeNG) -> None:
         """Check if inplace defined list / set can be replaced by a tuple."""
-        if isinstance(node.iter, (astroid.List, astroid.Set)) and not any(
-            isinstance(item, astroid.Starred) for item in node.iter.elts
+        if isinstance(node, (astroid.List, astroid.Set)) and not any(
+            isinstance(item, astroid.Starred) for item in node.elts
         ):
             self.add_message(
                 "consider-using-tuple",
-                node=node.iter,
-                args=(f" instead of {node.iter.__class__.__qualname__.lower()}"),
+                node=node,
+                args=(f" instead of {node.__class__.__qualname__.lower()}",),
             )
 
 

tests/functional/ext/code_style/code_style_consider_using_tuple.py

@@ -27,3 +27,30 @@
 
 [x for x in [*var, 2]]
 [x for x in {*var, 2}]
+
+
+# -----
+# Suggest tuple for `in` comparisons
+x in var
+x in (1, 2, 3)
+x in [1, 2, 3]  # [consider-using-tuple]
+
+if x in var:
+    pass
+if x in (1, 2, 3):
+    pass
+if x in [1, 2, 3]:  # [consider-using-tuple]
+    pass
+if x in {1, 2, 3}:  # [consider-using-tuple]
+    pass
+
+42 if x in [1, 2, 3] else None  # [consider-using-tuple]
+assert x in [1, 2, 3]  # [consider-using-tuple]
+(x for x in var if x in [1, 2, 3])  # [consider-using-tuple]
+while x in [1, 2, 3]:  # [consider-using-tuple]
+    break
+
+# Stacked operators, rightmost pair is evaluated first
+# Doesn't make much sense in practice since `in` will only return `bool`
+True == x in [1, 2, 3]  # [consider-using-tuple]  # noqa: E712
+1 >= x in [1, 2, 3]  # [consider-using-tuple]  # noqa: E712

tests/functional/ext/code_style/code_style_consider_using_tuple.txt

@@ -1,4 +1,13 @@
-consider-using-tuple:9:9::Consider using an in-place tuple instead of list
-consider-using-tuple:14:12::Consider using an in-place tuple instead of list
-consider-using-tuple:15:12::Consider using an in-place tuple instead of set
-consider-using-tuple:19:12::Consider using an in-place tuple instead of list
+consider-using-tuple:9:9::Consider using an in-place tuple instead of list:HIGH
+consider-using-tuple:14:12::Consider using an in-place tuple instead of list:HIGH
+consider-using-tuple:15:12::Consider using an in-place tuple instead of set:HIGH
+consider-using-tuple:19:12::Consider using an in-place tuple instead of list:HIGH
+consider-using-tuple:36:5::Consider using an in-place tuple instead of list:HIGH
+consider-using-tuple:42:8::Consider using an in-place tuple instead of list:HIGH
+consider-using-tuple:44:8::Consider using an in-place tuple instead of set:HIGH
+consider-using-tuple:47:11::Consider using an in-place tuple instead of list:HIGH
+consider-using-tuple:48:12::Consider using an in-place tuple instead of list:HIGH
+consider-using-tuple:49:24::Consider using an in-place tuple instead of list:HIGH
+consider-using-tuple:50:11::Consider using an in-place tuple instead of list:HIGH
+consider-using-tuple:55:13::Consider using an in-place tuple instead of list:HIGH
+consider-using-tuple:56:10::Consider using an in-place tuple instead of list:HIGH