Closes #1898, closes #1883

CHANGELOG.md

@@ -27,6 +27,7 @@ Semantic versioning in our case means:
 - Fixes `ReassigningVariableToItselfViolation` to extract variables
   from unary operators #1874
 - Fixes that `f'{some:,}'` was considered too complex #1921
+- Fixes that `range(len(x))` was not allowed even outside `for` loops #1883
 
 ### Misc
 

tests/test_visitors/test_ast/test_functions/test_call_context/test_range_len.py

@@ -7,6 +7,21 @@
     WrongFunctionCallContextVisitor,
 )
 
+for_template = """
+def function():
+    for list_item in {0}:
+        ...
+"""
+
+wrong_samples = (
+    'range(len())',
+    'range(len(some))',
+    'range(len([]))',
+    'range(1, len(some))',
+    'range(-1, len(some))',
+    'range(0, len(some), -1)',
+)
+
 
 @pytest.mark.parametrize('code', [
     'range(10)',
@@ -25,34 +40,45 @@ def test_correct_range_len(
     parse_ast_tree,
     code,
     default_options,
+    mode,
 ):
     """Testing that ``range()`` can be used."""
-    tree = parse_ast_tree(code)
+    tree = parse_ast_tree(mode(for_template.format(code)))
 
     visitor = WrongFunctionCallContextVisitor(default_options, tree=tree)
     visitor.run()
 
     assert_errors(visitor, [])
 
 
-@pytest.mark.parametrize('code', [
-    'range(len())',
-    'range(len(some))',
-    'range(len([]))',
-    'range(1, len(some))',
-    'range(-1, len(some))',
-    'range(0, len(some), -1)',
-])
+@pytest.mark.parametrize('code', wrong_samples)
 def test_range_len(
     assert_errors,
     parse_ast_tree,
     code,
     default_options,
+    mode,
 ):
     """Testing that ``range(len(...))`` cannot be used."""
-    tree = parse_ast_tree(code)
+    tree = parse_ast_tree(mode(for_template.format(code)))
 
     visitor = WrongFunctionCallContextVisitor(default_options, tree=tree)
     visitor.run()
 
     assert_errors(visitor, [ImplicitEnumerateViolation])
+
+
+@pytest.mark.parametrize('code', wrong_samples)
+def test_range_len_outside_for_loop(
+    assert_errors,
+    parse_ast_tree,
+    code,
+    default_options,
+):
+    """Testing that ``range(len(...))`` can be used outside loops."""
+    tree = parse_ast_tree(code)
+
+    visitor = WrongFunctionCallContextVisitor(default_options, tree=tree)
+    visitor.run()
+
+    assert_errors(visitor, [])

wemake_python_styleguide/visitors/ast/functions.py

@@ -4,7 +4,11 @@
 
 from typing_extensions import final
 
-from wemake_python_styleguide.compat.aliases import FunctionNodes, TextNodes
+from wemake_python_styleguide.compat.aliases import (
+    ForNodes,
+    FunctionNodes,
+    TextNodes,
+)
 from wemake_python_styleguide.compat.functions import get_posonlyargs
 from wemake_python_styleguide.constants import (
     FUNCTIONS_BLACKLIST,
@@ -240,6 +244,8 @@ def _check_type_compare(self, node: ast.Call) -> None:
             self.add_violation(TypeCompareViolation(node))
 
     def _check_range_len(self, node: ast.Call) -> None:
+        if not isinstance(nodes.get_parent(node), ForNodes):
+            return
         if not functions.given_function_called(node, {'range'}):
             return