improved self variable reassigning recognition

tests/test_visitors/test_ast/test_naming/test_variable_self_reassignment.py

@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
 
+import pytest
+
 from wemake_python_styleguide.violations.best_practices import (
     ReassigningVariableToItselfViolation,
 )
@@ -17,12 +19,34 @@
 test_variable = 10
 """
 
+wrong_fragment_double_assignment = """
+test_variable = 5
+test_variable = test_variable = 10
+"""
+
+wrong_fragment_other_assignment = """
+test_variable = 5
+test_variable = other = test_variable = 5
+"""
+
+wrong_fragment_tuple_assignment = """
+x = 1
+y = 2
+x, y = x, y
+"""
 
+
+@pytest.mark.parametrize('fragment', [wrong_fragment,
+                                      wrong_fragment_double_assignment,
+                                      wrong_fragment_other_assignment,
+                                      wrong_fragment_tuple_assignment,
+                                      ],
+                         )
 def test_self_variable_reassignment(
-    assert_errors, parse_ast_tree, default_options,
+    assert_errors, parse_ast_tree, fragment, default_options,
 ):
     """Testing that self variable reassignment is restricted."""
-    tree = parse_ast_tree(wrong_fragment)
+    tree = parse_ast_tree(fragment)
     visitor = WrongVariableAssignmentVisitor(default_options, tree=tree)
     visitor.run()
     assert_errors(visitor, [ReassigningVariableToItselfViolation])

wemake_python_styleguide/violations/best_practices.py

@@ -621,22 +621,6 @@ class RedundantForElseViolation(ASTViolation):
     code = 436
 
 
-class ReassigningVariableToItselfViolation(ASTViolation):
-    """
-    Forbids to assign variable to itself.
-
-    Reasoning:
-        There is no need to do that.
-
-    Note:
-        Returns Z437 as error code
-    """
-
-    #: Error message shown to the user.
-    error_template = 'Found reassigning variable to itself'
-    code = 437
-
-
 class RedundantFinallyViolation(ASTViolation):
     """
     Forbids to use ``finally`` in ``try`` block without ``except`` block.
@@ -662,10 +646,26 @@ class RedundantFinallyViolation(ASTViolation):
             f.close()
 
     Note:
-        Returns Z438 as error code
+        Returns Z437 as error code
 
     """
 
     #: Error message shown to the user.
     error_template = 'Found `finally` in `try` block without `except`'
+    code = 437
+
+
+class ReassigningVariableToItselfViolation(ASTViolation):
+    """
+    Forbids to assign variable to itself.
+
+    Reasoning:
+        There is no need to do that.
+
+    Note:
+        Returns Z438 as error code
+    """
+
+    #: Error message shown to the user.
+    error_template = 'Found reassigning variable to itself'
     code = 438

wemake_python_styleguide/visitors/ast/naming.py

@@ -172,10 +172,24 @@ class WrongVariableAssignmentVisitor(BaseNodeVisitor):
     """Finds wrong variables assignments."""
 
     def _check_assignment(self, node: ast.Assign) -> None:
-        node_value_id = getattr(node.value, 'id', None)
-        for target_node in node.targets:
-            target_node_id = getattr(target_node, 'id', None)
-            if target_node_id == node_value_id:
+        target_names = [target.id for target in node.targets
+                        if isinstance(target, ast.Name)]
+        if target_names:
+            if getattr(node.value, 'id', None) in target_names or (
+                    len(target_names) != len(list(set(target_names)))):
+                self.add_violation(ReassigningVariableToItselfViolation(node))
+        else:
+            target_names = [getattr(target, 'elts', None) for target
+                            in node.targets if isinstance(target, ast.Tuple)]
+            for index in range(len(target_names)):
+                target_names[index] = [name.id for name in target_names[index]]
+            node_values = []
+            if isinstance(node.value, ast.Tuple):
+                node_values = [getattr(node_value, 'id', None) for node_value
+                               in node.value.elts]
+            if node_values in target_names or (len(target_names) !=
+                                               len(list(set(target_names)))
+                                               ):
                 self.add_violation(ReassigningVariableToItselfViolation(node))
 
     def visit_Assign(self, node: ast.Assign) -> None:

wemake_python_styleguide/visitors/presets/general.py

@@ -33,6 +33,7 @@
 
     naming.WrongNameVisitor,
     naming.WrongModuleMetadataVisitor,
+    naming.WrongVariableAssignmentVisitor,
 
     numbers.MagicNumberVisitor,
     WrongStringVisitor,