Do not report WPS440 when ... is the only node in the function defition

CHANGELOG.md

@@ -21,7 +21,10 @@ Semantic versioning in our case means:
 
 ### Bugfixes
 
-- Fixes `TooDeepNestingViolation` not to trigger on `...`
+- Fixes `TooDeepNestingViolation` not to trigger
+  on `...` in functions and classes
+- Fixes `StatementHasNoEffectViolation` not to trigger
+  on `...` in functions and classes, when it is the only node
 
 
 ## 0.19.0

tests/test_visitors/test_ast/test_complexity/test_offset_visitor.py

@@ -96,6 +96,10 @@ class MyClass:
     def function_with_really_long_name(self): ...
 """
 
+top_level_class_ellipsis = """
+class MyClassWithReallyLongName: ...
+"""
+
 
 @pytest.mark.parametrize('code', [
     nested_if,
@@ -121,6 +125,7 @@ def function_with_really_long_name(self): ...
     ),
     top_level_function_ellipsis,
     top_level_method_ellipsis,
+    top_level_class_ellipsis,
 ])
 def test_nested_offset(
     assert_errors,

tests/test_visitors/test_ast/test_statements/test_statements_with_no_effect.py

@@ -109,13 +109,25 @@ def function():
     {0}
 """
 
+function_extra_template = """
+def function():
+    x = 1
+    ...
+"""
+
 # Classes:
 
 class_template = """
 class Test:
     {0}
 """
 
+class_extra_template = """
+class Test:
+    x = 1
+    {0}
+"""
+
 # Async:
 
 async_function_template = """
@@ -390,21 +402,49 @@ def test_statement_with_docstring(
     async_with_template,
     async_for_template,
     async_for_else_template,
+
+    function_extra_template,
+    class_extra_template,
 ])
 @pytest.mark.parametrize('statement', [
     '"docstring"',
+    '...',
 ])
-def test_statement_with_useless_docstring(
+def test_statement_useless_special_statements(
     assert_errors,
     parse_ast_tree,
     code,
     statement,
     default_options,
 ):
-    """Testing that docstring works."""
+    """Testing that docstring and `...` work."""
     tree = parse_ast_tree(code.format(statement))
 
     visitor = StatementsWithBodiesVisitor(default_options, tree=tree)
     visitor.run()
 
     assert_errors(visitor, [StatementHasNoEffectViolation])
+
+
+@pytest.mark.parametrize('code', [
+    function_template,
+    class_template,
+    async_function_template,
+])
+@pytest.mark.parametrize('statement', [
+    '...'
+])
+def test_statement_ellipsis_has_effect_on_definition(
+    assert_errors,
+    parse_ast_tree,
+    code,
+    statement,
+    default_options,
+):
+    """Testing that `...` works."""
+    tree = parse_ast_tree(code.format(statement))
+
+    visitor = StatementsWithBodiesVisitor(default_options, tree=tree)
+    visitor.run()
+
+    assert_errors(visitor, [])

wemake_python_styleguide/violations/best_practices.py

@@ -1229,6 +1229,10 @@ def some_function():
 
     .. versionadded:: 0.5.0
     .. versionchanged:: 0.11.0
+    .. versionchanged:: 0.19.1
+       Do not report ``...`` when used in a
+       function or class body as a single node.
+
     """
 
     error_template = 'Found statement that has no effect'

wemake_python_styleguide/violations/complexity.py

@@ -681,6 +681,8 @@ class TooDeepNestingViolation(ASTViolation):
 
     .. versionadded:: 0.1.0
     .. versionchanged:: 0.5.0
+    .. versionchanged:: 0.19.1
+       Do not report ``...`` when used in a function or class body.
 
     """
 

wemake_python_styleguide/visitors/ast/complexity/offset.py

@@ -58,7 +58,7 @@ def visit_line_expression(self, node: ast.AST) -> None:
 
     def _check_offset(self, node: ast.AST) -> None:
         is_function_ellipsis = (
-            isinstance(get_parent(node), FunctionNodes) and
+            isinstance(get_parent(node), (*FunctionNodes, ast.ClassDef)) and
             isinstance(node, ast.Expr) and
             isinstance(node.value, ast.Constant) and
             node.value.value is Ellipsis

wemake_python_styleguide/visitors/ast/statements.py

@@ -220,6 +220,7 @@ def _check_useless_node(
     def _check_expression(
         self,
         node: ast.Expr,
+        *,
         is_first: bool = False,
     ) -> None:
         if isinstance(node.value, self._have_effect):
@@ -229,6 +230,16 @@ def _check_expression(
             if isinstance(nodes.get_parent(node), self._have_doc_strings):
                 return
 
+        parent = nodes.get_parent(node)
+        is_only_ellipsis_node = (
+            isinstance(node.value, ast.Constant) and
+            node.value.value is Ellipsis and
+            isinstance(parent, (*FunctionNodes, ast.ClassDef)) and
+            len(parent.body) == 1
+        )
+        if is_only_ellipsis_node:
+            return
+
         self.add_violation(StatementHasNoEffectViolation(node))
 
     def _check_self_misrefactored_assignment(