Don't trigger E721 when comparing with None (#1356)

resources/test/fixtures/pycodestyle/E721.py

@@ -15,7 +15,7 @@ import types
 if type(res) is not types.ListType:
     pass
 #: E721
-assert type(res) == type(False) or type(res) == type(None)
+assert type(res) == type(False)
 #: E721
 assert type(res) == type([])
 #: E721
@@ -52,3 +52,5 @@ if isinstance(res, types.MethodType):
     pass
 if type(a) != type(b) or type(a) == type(ccc):
     pass
+
+assert type(res) == type(None)

src/pycodestyle/checks.rs

@@ -1,7 +1,7 @@
 use itertools::izip;
 use once_cell::sync::Lazy;
 use regex::Regex;
-use rustpython_ast::{Located, Location, Stmt, StmtKind};
+use rustpython_ast::{Constant, Located, Location, Stmt, StmtKind};
 use rustpython_parser::ast::{Cmpop, Expr, ExprKind};
 
 use crate::ast::types::Range;
@@ -55,7 +55,14 @@ pub fn type_comparison(ops: &[Cmpop], comparators: &[Expr], location: Range) ->
                     if id == "type" {
                         if let Some(arg) = args.first() {
                             // Allow comparison for types which are not obvious.
-                            if !matches!(arg.node, ExprKind::Name { .. }) {
+                            if !matches!(
+                                arg.node,
+                                ExprKind::Name { .. }
+                                    | ExprKind::Constant {
+                                        value: Constant::None,
+                                        kind: None
+                                    }
+                            ) {
                                 checks.push(Check::new(CheckKind::TypeComparison, location));
                             }
                         }

src/pycodestyle/snapshots/ruff__pycodestyle__tests__E721_E721.py.snap

@@ -42,14 +42,6 @@ expression: checks
     row: 18
     column: 31
   fix: ~
-- kind: TypeComparison
-  location:
-    row: 18
-    column: 35
-  end_location:
-    row: 18
-    column: 58
-  fix: ~
 - kind: TypeComparison
   location:
     row: 20