Adds a new rule to forbid extra syntax in pm subjects, closes #3217 (#…

…3229)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

CHANGELOG.md

@@ -123,6 +123,7 @@ Semantic versioning in our case means:
 - Adds a new rule to find too many `PEP695` type params
 - Adds a new rule to find useless ternary expressions, #1706
 - Adds a new rule to forbid `raise SystemError`, use `sys.exit` instead, #1786
+- Adds a new rule to forbid extra syntax in `match ...` subjects, #3217
 - Adds support to run `wemake-python-styleguide` as a `pre-commit` hook, #2588
 - GitHub Action can now use `cwd:` parameter to specify
   where your configuration file is, #2474

tests/fixtures/noqa/noqa.py

@@ -667,6 +667,10 @@ def foo2_func():
     case SomeClass():
         my_print('second')
 
+match [some_value]:  # noqa: WPS536
+    case SomeClass():
+        my_print('first')
+
 class Baseline:
     def method(self, number):
         return number + 1

tests/test_checker/test_noqa.py

@@ -270,6 +270,7 @@
         'WPS533': 1,
         'WPS534': 1,
         'WPS535': 1,
+        'WPS536': 1,
         'WPS600': 1,
         'WPS601': 1,
         'WPS602': 2,

tests/test_violations/test_codes.py

@@ -1,13 +1,18 @@
 from collections import Counter
 
+import pytest
+
+from wemake_python_styleguide.compat.constants import PY311
+
 
 def test_all_unique_violation_codes(all_violations):
     """Ensures that all violations have unique violation codes."""
     codes = [int(violation.code) for violation in all_violations]
     assert len(set(codes)) == len(all_violations)
 
 
-def test_all_violations_are_final(all_violations):
+@pytest.mark.skipif(not PY311, reason='@final has runtime effect since 3.11')
+def test_all_violations_are_final(all_violations):  # pragma: >=3.11 cover
     """Ensures that all violations are final."""
     for violation_type in all_violations:
         assert getattr(violation_type, '__final__', False), violation_type

tests/test_visitors/test_ast/test_pm/test_extra_subject_syntax.py

@@ -0,0 +1,67 @@
+import pytest
+
+from wemake_python_styleguide.violations.refactoring import (
+    ExtraMatchSubjectSyntaxViolation,
+)
+from wemake_python_styleguide.visitors.ast.pm import MatchSubjectVisitor
+
+template = """
+match {0}:
+    case SomeClass():
+        my_print('first')
+"""
+
+
+@pytest.mark.parametrize(
+    'code',
+    [
+        '[Some()]',
+        '[first, second]',
+        '{var, other}',
+        '{test : result}',
+        '{test : "value"}',
+        '(one,)',
+    ],
+)
+def test_wrong_usage_of_subjects(
+    assert_errors,
+    parse_ast_tree,
+    code,
+    default_options,
+):
+    """Ensures that extra syntax in subjects are forbidden."""
+    tree = parse_ast_tree(template.format(code))
+
+    visitor = MatchSubjectVisitor(default_options, tree=tree)
+    visitor.run()
+
+    assert_errors(visitor, [ExtraMatchSubjectSyntaxViolation])
+
+
+@pytest.mark.parametrize(
+    'code',
+    [
+        'first',
+        'call()',
+        'attr.value',
+        '(first, second)',
+        '(many, items, here)',
+        # Will raise another violation:
+        '[1, 2]',
+        '()',
+        '[]',
+    ],
+)
+def test_correct_usage_of_subjects(
+    assert_errors,
+    parse_ast_tree,
+    code,
+    default_options,
+):
+    """Ensures that it is possible to have correct subjects."""
+    tree = parse_ast_tree(template.format(code))
+
+    visitor = MatchSubjectVisitor(default_options, tree=tree)
+    visitor.run()
+
+    assert_errors(visitor, [])

wemake_python_styleguide/checker.py

@@ -40,10 +40,9 @@
 import tokenize
 import traceback
 from collections.abc import Iterator, Sequence
-from typing import ClassVar, TypeAlias
+from typing import ClassVar, TypeAlias, final
 
 from flake8.options.manager import OptionManager
-from typing_extensions import final
 
 from wemake_python_styleguide import constants, types
 from wemake_python_styleguide import version as pkg_version

wemake_python_styleguide/logic/complexity/functions.py

@@ -1,8 +1,7 @@
 from collections import defaultdict
-from typing import TypeAlias
+from typing import TypeAlias, final
 
 import attr
-from typing_extensions import final
 
 from wemake_python_styleguide.types import (
     AnyFunctionDef,

wemake_python_styleguide/options/config.py

@@ -168,11 +168,10 @@ class of violations that are forbidden to ignore inline, defaults to
 """
 
 from collections.abc import Mapping, Sequence
-from typing import ClassVar, Final, TypeAlias
+from typing import ClassVar, Final, TypeAlias, final
 
 import attr
 from flake8.options.manager import OptionManager
-from typing_extensions import final
 
 from wemake_python_styleguide.options import defaults
 

wemake_python_styleguide/options/validation.py

@@ -1,5 +1,6 @@
+from typing import final
+
 import attr
-from typing_extensions import final
 
 from wemake_python_styleguide.options import defaults
 from wemake_python_styleguide.types import ConfigurationOptions

wemake_python_styleguide/presets/types/tree.py

@@ -16,6 +16,7 @@
     loops,
     modules,
     operators,
+    pm,
     redundancy,
     statements,
     subscripts,
@@ -82,6 +83,7 @@
     subscripts.CorrectKeyVisitor,
     decorators.WrongDecoratorVisitor,
     redundancy.RedundantEnumerateVisitor,
+    pm.MatchSubjectVisitor,
     # Modules:
     modules.EmptyModuleContentsVisitor,
     modules.MagicModuleFunctionsVisitor,

wemake_python_styleguide/types.py

@@ -36,9 +36,7 @@
 """
 
 import ast
-from typing import TypeAlias
-
-from typing_extensions import Protocol
+from typing import Protocol, TypeAlias
 
 #: In cases we need to work with both import types.
 AnyImport: TypeAlias = ast.Import | ast.ImportFrom

wemake_python_styleguide/violations/base.py

@@ -54,9 +54,7 @@ class SomeViolation(ASTViolation):
 import enum
 import tokenize
 from collections.abc import Callable
-from typing import ClassVar, TypeAlias
-
-from typing_extensions import final
+from typing import ClassVar, TypeAlias, final
 
 #: General type for all possible nodes where error happens.
 ErrorNode: TypeAlias = ast.AST | tokenize.TokenInfo | None

wemake_python_styleguide/violations/best_practices.py

@@ -175,7 +175,7 @@
 
 """
 
-from typing_extensions import final
+from typing import final
 
 from wemake_python_styleguide.violations.base import (
     ASTViolation,

wemake_python_styleguide/violations/complexity.py

@@ -112,7 +112,7 @@
 
 """
 
-from typing_extensions import final
+from typing import final
 
 from wemake_python_styleguide.violations.base import (
     ASTViolation,

wemake_python_styleguide/violations/consistency.py

@@ -158,7 +158,7 @@
 
 """
 
-from typing_extensions import final
+from typing import final
 
 from wemake_python_styleguide.violations.base import (
     ASTViolation,

wemake_python_styleguide/violations/naming.py

@@ -175,7 +175,7 @@
 
 """
 
-from typing_extensions import final
+from typing import final
 
 from wemake_python_styleguide.violations.base import (
     ASTViolation,

wemake_python_styleguide/violations/oop.py

@@ -55,7 +55,7 @@
 
 """
 
-from typing_extensions import final
+from typing import final
 
 from wemake_python_styleguide.violations.base import ASTViolation
 

wemake_python_styleguide/violations/refactoring.py

@@ -49,6 +49,7 @@
    DuplicateIfConditionViolation
    UselessTernaryViolation
    DuplicateCasePatternViolation
+   ExtraMatchSubjectSyntaxViolation
 
 Refactoring opportunities
 -------------------------
@@ -89,10 +90,11 @@
 .. autoclass:: DuplicateIfConditionViolation
 .. autoclass:: UselessTernaryViolation
 .. autoclass:: DuplicateCasePatternViolation
+.. autoclass:: ExtraMatchSubjectSyntaxViolation
 
 """
 
-from typing_extensions import final
+from typing import final
 
 from wemake_python_styleguide.violations.base import (
     ASTViolation,
@@ -1414,3 +1416,36 @@ class DuplicateCasePatternViolation(ASTViolation):
 
     error_template = 'Found duplicate `case` pattern: {0}'
     code = 535
+
+
+@final
+class ExtraMatchSubjectSyntaxViolation(ASTViolation):
+    """
+    Forbid extra syntax around ``match`` like ``[]`` or ``{ ... }``.
+
+    Reasoning:
+        Adding extra lists / sets / dicts around your ``match`` subjects
+        is just adding more complexity.
+
+    Solution:
+        Use raw values or tuples instead.
+
+    Example::
+
+        # Correct:
+        match some:
+            case SomeClass(): ...
+
+        match (first, second):
+            case (1, 2): ...
+
+        # Wrong:
+        match [first, second]:
+            case [1, 2]: ...
+
+    .. versionadded:: 1.0.0
+
+    """
+
+    error_template = 'Found `match` subject with extra syntax: {0}'
+    code = 536

wemake_python_styleguide/violations/system.py

@@ -22,7 +22,7 @@
 
 """
 
-from typing_extensions import final
+from typing import final
 
 from wemake_python_styleguide.violations.base import SimpleViolation
 

wemake_python_styleguide/visitors/ast/blocks.py

@@ -1,8 +1,6 @@
 import ast
 from collections import defaultdict
-from typing import TypeAlias, cast
-
-from typing_extensions import final
+from typing import TypeAlias, cast, final
 
 from wemake_python_styleguide.compat.aliases import ForNodes, WithNodes
 from wemake_python_styleguide.logic import walk

wemake_python_styleguide/visitors/ast/builtins.py

@@ -1,9 +1,7 @@
 import ast
 import string
 from collections.abc import Sequence
-from typing import ClassVar, Final, TypeAlias
-
-from typing_extensions import final
+from typing import ClassVar, Final, TypeAlias, final
 
 from wemake_python_styleguide import constants
 from wemake_python_styleguide.compat.aliases import (

wemake_python_styleguide/visitors/ast/classes.py

@@ -1,8 +1,6 @@
 import ast
 from collections import defaultdict
-from typing import ClassVar
-
-from typing_extensions import final
+from typing import ClassVar, final
 
 from wemake_python_styleguide import constants, types
 from wemake_python_styleguide.compat.aliases import AssignNodes, FunctionNodes

wemake_python_styleguide/visitors/ast/compares.py

@@ -1,7 +1,5 @@
 import ast
-from typing import ClassVar
-
-from typing_extensions import final
+from typing import ClassVar, final
 
 from wemake_python_styleguide.logic import nodes, walk
 from wemake_python_styleguide.logic.naming.name_nodes import is_same_variable
@@ -187,7 +185,8 @@ def _check_constant_condition(
             if is_match and not pattern_matching.is_constant_subject(real_node):
                 return
             if not is_match and not isinstance(
-                real_node, self._forbidden_nodes
+                real_node,
+                self._forbidden_nodes,
             ):
                 return
             self.add_violation(ConstantConditionViolation(node))

wemake_python_styleguide/visitors/ast/complexity/access.py

@@ -1,8 +1,6 @@
 import ast
 from itertools import takewhile
-from typing import ClassVar, cast
-
-from typing_extensions import final
+from typing import ClassVar, cast, final
 
 from wemake_python_styleguide.logic.tree import attributes
 from wemake_python_styleguide.types import AnyAccess, AnyNodes

wemake_python_styleguide/visitors/ast/complexity/annotations.py

@@ -1,6 +1,5 @@
 import ast
-
-from typing_extensions import final
+from typing import final
 
 from wemake_python_styleguide.logic.complexity.annotations import (
     get_annotation_complexity,

wemake_python_styleguide/visitors/ast/complexity/calls.py

@@ -1,7 +1,6 @@
 import ast
 from itertools import takewhile
-
-from typing_extensions import final
+from typing import final
 
 from wemake_python_styleguide.logic.tree.calls import parts
 from wemake_python_styleguide.violations.complexity import (

wemake_python_styleguide/visitors/ast/complexity/classes.py

@@ -1,7 +1,6 @@
 import ast
 from collections import defaultdict
-
-from typing_extensions import final
+from typing import final
 
 from wemake_python_styleguide.logic.naming import access
 from wemake_python_styleguide.logic.nodes import get_parent