Fix for issue 649.

tests/test_visitors/test_ast/test_keywords/test_consistency_returning/test_consistency_return_variables.py

@@ -62,6 +62,26 @@ def foo():
    return x[0]
 """
 
+correct_example9 = """
+def test():
+     print('test')
+"""
+
+correct_example10 = """
+def test(some):
+     if some:
+          return
+     print('test')
+"""
+
+correct_example11 = """
+def test(some):
+     if some:
+          return some
+     print('test')
+     return None
+"""
+
 # Wrong:
 
 wrong_example1 = """
@@ -103,6 +123,26 @@ def decorator(*args, **kwargs):
     return decorator
 """
 
+wrong_example6 = """
+def test():
+     print('test')
+     return None
+"""
+
+wrong_example7 = """
+def test():
+     print('test')
+     return
+"""
+
+wrong_example8 = """
+def test(some):
+     if some:
+          return
+     print('test')
+     return
+"""
+
 double_wrong_example1 = """
 def some():
    if something() == 1:
@@ -121,6 +161,9 @@ def some():
     wrong_example3,
     wrong_example4,
     wrong_example5,
+    wrong_example6,
+    wrong_example7,
+    wrong_example8
 ])
 def test_wrong_return_variable(
     assert_errors,
@@ -146,6 +189,9 @@ def test_wrong_return_variable(
     correct_example6,
     correct_example7,
     correct_example8,
+    correct_example9,
+    correct_example10,
+    correct_example11,
 ])
 def test_correct_return_statements(
     assert_errors,

wemake_python_styleguide/visitors/ast/keywords.py

@@ -289,7 +289,8 @@ def _check_variables_for_return(self, node: AnyFunctionDef) -> None:
         returns, return_sub_nodes = self._get_return_node_variables(nodes)
 
         returns = {name: returns[name] for name in returns if name in assign}
-
+        if not return_sub_nodes:
+            self._check_return_at_the_end(node)
         self._check_for_violations(names, return_sub_nodes, returns)
 
     def _check_for_violations(self, names, return_sub_nodes, returns) -> None:
@@ -301,6 +302,21 @@ def _check_for_violations(self, names, return_sub_nodes, returns) -> None:
                     ),
                 )
 
+    def _check_return_at_the_end(self, node):
+        if len(node.body) <= 1:
+            return
+        last = node.body[-1]
+        if isinstance(last, ast.Return):
+            if last.value is None:
+                self.add_violation(
+                    InconsistentReturnVariableViolation(last),
+                )
+            elif isinstance(last.value, ast.NameConstant) and (last.value.value is None):
+                self.add_violation(
+                    InconsistentReturnVariableViolation(last),
+                )
+
+
     def visit_return_variable(self, node: AnyFunctionDef) -> None:
         """
         Helper to get all ``return`` variables in a function at once.