Issue 3265: Add WPS476 SneakyTypeVarWithDefaultViolation

CHANGELOG.md

@@ -19,6 +19,10 @@ Semantic versioning in our case means:
 
 ## 1.1.0 WIP
 
+### Rules
+
+- Adds `WPS476`: do not allow `TypeVarTuple` after a `TypeVar` with a default #3265
+
 ### Command line utility
 
 This version introduces `wps` CLI tool.

tests/fixtures/noqa/noqa313.py

@@ -0,0 +1,11 @@
+"""
+This file contains all possible violations for python 3.13+.
+
+It is used for e2e tests.
+"""
+
+class NewStyleGenerics[
+    TypeVarDefault=int,
+    *FollowingTuple=*tuple[int, ...]  # noqa: WPS476
+]:
+    """TypeVarTuple follows a defaulted TypeVar."""

tests/test_checker/test_noqa.py

@@ -33,6 +33,11 @@
     'WPS402',  # we obviously use a lot of `noqa` comments
 )
 
+#: List of ignored violations on python 3.13+.
+IGNORED_VIOLATIONS3_13 = (
+
+)
+
 #: Number and count of violations that would be raised.
 SHOULD_BE_RAISED = types.MappingProxyType(
     {
@@ -234,6 +239,7 @@
         'WPS473': 0,
         'WPS474': 1,
         'WPS475': 1,
+        'WPS476': 0,  # enabled only in python 3.13+
         'WPS500': 1,
         'WPS501': 1,
         'WPS502': 0,  # disabled since 1.0.0
@@ -292,6 +298,13 @@
     },
 )
 
+#: Number and count of violations that would be raised in 3.13+ section.
+SHOULD_BE_RAISED3_13 = types.MappingProxyType(
+    dict.fromkeys(SHOULD_BE_RAISED, 0) | {
+        'WPS476': 1
+    }
+)
+
 
 def _assert_errors_count_in_output(
     output,
@@ -324,6 +337,7 @@ def test_codes(all_violations):
     ('filename', 'violations'),
     [
         ('noqa.py', SHOULD_BE_RAISED),
+        ('noqa313.py', SHOULD_BE_RAISED3_13),
     ],
 )
 def test_noqa_fixture_disabled(
@@ -360,7 +374,14 @@ def test_noqa_fixture_disabled(
     )
 
 
-def test_noqa_fixture(absolute_path):
+@pytest.mark.parametrize(
+    'filename',
+    [
+        'noqa.py',
+        'noqa313.py',
+    ]
+)
+def test_noqa_fixture(absolute_path, filename):
     """End-to-End test to check that `noqa` works."""
     process = subprocess.Popen(
         [
@@ -370,7 +391,7 @@ def test_noqa_fixture(absolute_path):
             '--isolated',
             '--select',
             'WPS, E999',
-            absolute_path('fixtures', 'noqa', 'noqa.py'),
+            absolute_path('fixtures', 'noqa', filename),
         ],
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
@@ -383,15 +404,24 @@ def test_noqa_fixture(absolute_path):
     assert not stderr.count('WPS')
 
 
-def test_noqa_fixture_without_ignore(absolute_path):
+@pytest.mark.parametrize(
+    ('filename', 'ignored_violations'),
+    [
+        ('noqa.py', IGNORED_VIOLATIONS),
+        ('noqa313.py', IGNORED_VIOLATIONS3_13),
+    ]
+)
+def test_noqa_fixture_without_ignore(
+    absolute_path, filename, ignored_violations
+):
     """End-to-End test to check that `noqa` works without ignores."""
     process = subprocess.Popen(
         [
             'flake8',
             '--isolated',
             '--select',
             'WPS, E999',
-            absolute_path('fixtures', 'noqa', 'noqa.py'),
+            absolute_path('fixtures', 'noqa', filename),
         ],
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
@@ -400,5 +430,5 @@ def test_noqa_fixture_without_ignore(absolute_path):
     )
     stdout, _ = process.communicate()
 
-    for violation in IGNORED_VIOLATIONS:
+    for violation in ignored_violations:
         assert stdout.count(violation) > 0

tests/test_visitors/test_ast/test_classes/test_base_classes/test_base_builtin_classes.py

@@ -1,7 +1,9 @@
 import pytest
 
 from wemake_python_styleguide.violations.oop import BuiltinSubclassViolation
-from wemake_python_styleguide.visitors.ast.classes import WrongClassDefVisitor
+from wemake_python_styleguide.visitors.ast.classes.classdef import (
+    WrongClassDefVisitor,
+)
 
 class_with_base = 'class TestClass({0}): ...'
 

tests/test_visitors/test_ast/test_classes/test_base_classes/test_base_exception_base_class.py

@@ -1,7 +1,9 @@
 from wemake_python_styleguide.violations.best_practices import (
     BaseExceptionSubclassViolation,
 )
-from wemake_python_styleguide.visitors.ast.classes import WrongClassDefVisitor
+from wemake_python_styleguide.visitors.ast.classes.classdef import (
+    WrongClassDefVisitor,
+)
 
 class_with_base = """
 class Meta({0}):

tests/test_visitors/test_ast/test_classes/test_base_classes/test_class_definition_arguments.py

@@ -3,7 +3,9 @@
 from wemake_python_styleguide.violations.best_practices import (
     KwargsUnpackingInClassDefinitionViolation,
 )
-from wemake_python_styleguide.visitors.ast.classes import WrongClassDefVisitor
+from wemake_python_styleguide.visitors.ast.classes.classdef import (
+    WrongClassDefVisitor,
+)
 
 # Wrong:
 

tests/test_visitors/test_ast/test_classes/test_base_classes/test_expression_base_class.py

@@ -1,7 +1,9 @@
 import pytest
 
 from wemake_python_styleguide.violations.oop import WrongBaseClassViolation
-from wemake_python_styleguide.visitors.ast.classes import WrongClassDefVisitor
+from wemake_python_styleguide.visitors.ast.classes.classdef import (
+    WrongClassDefVisitor,
+)
 
 class_with_base = """
 class Meta({0}):

tests/test_visitors/test_ast/test_classes/test_buggy_super.py

@@ -1,7 +1,9 @@
 import pytest
 
 from wemake_python_styleguide.violations.oop import BuggySuperContextViolation
-from wemake_python_styleguide.visitors.ast.classes import BuggySuperCallVisitor
+from wemake_python_styleguide.visitors.ast.classes.methods import (
+    BuggySuperCallVisitor,
+)
 
 error_dict_comprehension = """
     {super().make_key(it): make_value(it) for it in items}

tests/test_visitors/test_ast/test_classes/test_class_attributes/test_shadow_attributes.py

@@ -3,7 +3,9 @@
 from wemake_python_styleguide.violations.oop import (
     ShadowedClassAttributeViolation,
 )
-from wemake_python_styleguide.visitors.ast.classes import ClassAttributeVisitor
+from wemake_python_styleguide.visitors.ast.classes.attributes import (
+    ClassAttributeVisitor,
+)
 
 # Can raise:
 

tests/test_visitors/test_ast/test_classes/test_class_attributes/test_slots_syntax.py

@@ -1,7 +1,9 @@
 import pytest
 
 from wemake_python_styleguide.violations.oop import WrongSlotsViolation
-from wemake_python_styleguide.visitors.ast.classes import WrongSlotsVisitor
+from wemake_python_styleguide.visitors.ast.classes.attributes import (
+    WrongSlotsVisitor,
+)
 
 class_body_template = """
 class ClassWithSlots:

tests/test_visitors/test_ast/test_classes/test_getter_setter.py

@@ -3,7 +3,9 @@
 from wemake_python_styleguide.violations.oop import (
     UnpythonicGetterSetterViolation,
 )
-from wemake_python_styleguide.visitors.ast.classes import WrongClassBodyVisitor
+from wemake_python_styleguide.visitors.ast.classes.classdef import (
+    WrongClassBodyVisitor,
+)
 
 module_getter_and_setter = """
 attribute = 1

tests/test_visitors/test_ast/test_classes/test_lambda_attr_assign.py

@@ -3,7 +3,9 @@
 from wemake_python_styleguide.violations.oop import (
     LambdaAttributeAssignedViolation,
 )
-from wemake_python_styleguide.visitors.ast.classes import ClassAttributeVisitor
+from wemake_python_styleguide.visitors.ast.classes.attributes import (
+    ClassAttributeVisitor,
+)
 
 # Correct:
 

tests/test_visitors/test_ast/test_classes/test_method_order.py

@@ -3,7 +3,7 @@
 from wemake_python_styleguide.violations.consistency import (
     WrongMethodOrderViolation,
 )
-from wemake_python_styleguide.visitors.ast.classes import (
+from wemake_python_styleguide.visitors.ast.classes.methods import (
     ClassMethodOrderVisitor,
 )
 

tests/test_visitors/test_ast/test_classes/test_methods/test_async_magic_methods.py

@@ -1,7 +1,9 @@
 import pytest
 
 from wemake_python_styleguide.violations.oop import AsyncMagicMethodViolation
-from wemake_python_styleguide.visitors.ast.classes import WrongMethodVisitor
+from wemake_python_styleguide.visitors.ast.classes.methods import (
+    WrongMethodVisitor,
+)
 
 sync_method = """
 class Example:

tests/test_visitors/test_ast/test_classes/test_methods/test_async_yield_magic_methods.py

@@ -1,7 +1,9 @@
 import pytest
 
 from wemake_python_styleguide.violations.oop import AsyncMagicMethodViolation
-from wemake_python_styleguide.visitors.ast.classes import WrongMethodVisitor
+from wemake_python_styleguide.visitors.ast.classes.methods import (
+    WrongMethodVisitor,
+)
 
 sync_method = """
 class Example:

tests/test_visitors/test_ast/test_classes/test_methods/test_magic_methods.py

@@ -2,7 +2,9 @@
 
 from wemake_python_styleguide.constants import MAGIC_METHODS_BLACKLIST
 from wemake_python_styleguide.violations.oop import BadMagicMethodViolation
-from wemake_python_styleguide.visitors.ast.classes import WrongMethodVisitor
+from wemake_python_styleguide.visitors.ast.classes.methods import (
+    WrongMethodVisitor,
+)
 
 magic_method = """
 class Example:

tests/test_visitors/test_ast/test_classes/test_methods/test_method_without_arguments.py

@@ -4,7 +4,9 @@
     MethodWithoutArgumentsViolation,
     StaticMethodViolation,
 )
-from wemake_python_styleguide.visitors.ast.classes import WrongMethodVisitor
+from wemake_python_styleguide.visitors.ast.classes.methods import (
+    WrongMethodVisitor,
+)
 
 method_inside_class = """
 class Example:

tests/test_visitors/test_ast/test_classes/test_methods/test_staticmethod.py

@@ -1,7 +1,9 @@
 import pytest
 
 from wemake_python_styleguide.violations.oop import StaticMethodViolation
-from wemake_python_styleguide.visitors.ast.classes import WrongMethodVisitor
+from wemake_python_styleguide.visitors.ast.classes.methods import (
+    WrongMethodVisitor,
+)
 
 decorated_method = """
 class Example:

tests/test_visitors/test_ast/test_classes/test_methods/test_useless_overwriting_method.py

@@ -3,7 +3,9 @@
 import pytest
 
 from wemake_python_styleguide.violations import oop
-from wemake_python_styleguide.visitors.ast.classes import WrongMethodVisitor
+from wemake_python_styleguide.visitors.ast.classes.methods import (
+    WrongMethodVisitor,
+)
 
 regular_method_detailed = """
 class Useless:

tests/test_visitors/test_ast/test_classes/test_methods/test_yield_magic_method.py

@@ -1,7 +1,9 @@
 import pytest
 
 from wemake_python_styleguide.violations.oop import YieldMagicMethodViolation
-from wemake_python_styleguide.visitors.ast.classes import WrongMethodVisitor
+from wemake_python_styleguide.visitors.ast.classes.methods import (
+    WrongMethodVisitor,
+)
 
 method_template = """
 class Test:

tests/test_visitors/test_ast/test_classes/test_type_var_with_default.py

@@ -0,0 +1,89 @@
+from typing import Final
+
+import pytest
+
+from wemake_python_styleguide.violations.best_practices import (
+    SneakyTypeVarWithDefaultViolation,
+)
+from wemake_python_styleguide.visitors.ast.classes.classdef import (
+    ConsecutiveDefaultTypeVarsVisitor,
+)
+
+class_header_formats: Final = ['Class[{0}]', 'Class(Generic[{0}])']
+various_code: Final = (
+    'pi = 3.14\n'
+    'a = obj.method_call()\n'
+    'w, h = get_size()\n'
+    'obj.field = function_call()\n'
+    'AlmostTypeVar = NotReallyATypeVar()\n'
+    "NonDefault = TypeVar('NonDefault')\n"
+)
+classes_with_various_bases: Final = (
+    'class SimpleBase(object): ...\n'
+    'class NotANameSubscript(Some.Class[object]): ...\n'
+    'class NotAGenericBase(NotAGeneric[T]): ...\n'
+    'class OldGenericDefinition(Generic[T]): ...\n'
+)
+
+
+def test_sneaky_type_var_with_default(
+    assert_errors,
+    parse_ast_tree,
+    default_options,
+):
+    """Test that WPS476 works correctly."""
+    src = (
+        f'{classes_with_various_bases}\n'
+        '\n'
+        f'class Class[T=int, *Ts=*tuple[int, ...]]:\n'
+        '    ...'
+    )
+
+    tree = parse_ast_tree(src)
+
+    visitor = ConsecutiveDefaultTypeVarsVisitor(default_options, tree=tree)
+    visitor.run()
+
+    assert_errors(visitor, [SneakyTypeVarWithDefaultViolation])
+
+
+@pytest.mark.parametrize(
+    'class_header',
+    [
+        (
+            "T = TypeVar('T')\n"
+            "Ts = TypeVarTuple('Ts')\n"
+            '\n'
+            'class Class(Generic[T, *Ts]):'
+        ),
+        (
+            "T = TypeVar('T', default=int)\n"
+            "Ts = TypeVarTuple('Ts')\n"
+            '\n'
+            'class Class(Generic[T, *Ts]):'
+        ),
+        (
+            'class Class[T, *Ts]:'
+        )
+    ],
+)
+def test_type_var_ignored(
+    assert_errors,
+    parse_ast_tree,
+    default_options,
+    class_header,
+):
+    """Test that WPS476 ignores non-defaulted and old TypeVars."""
+    src = (
+        f'{various_code}\n'
+        f'{classes_with_various_bases}\n'
+        f'{class_header}\n'
+        '    ...'
+    )
+
+    tree = parse_ast_tree(src)
+
+    visitor = ConsecutiveDefaultTypeVarsVisitor(default_options, tree=tree)
+    visitor.run()
+
+    assert_errors(visitor, [])