[tests] Fix tests to report an error when classes are used as a mixin, even in the same library.

Change-Id: Icdb4c4e87bf3143ea9c37272f27e7eac0c7613a6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/283129
Reviewed-by: Lasse Nielsen <lrn@google.com>
Commit-Queue: Kallen Tu <kallentu@google.com>

tests/language/class_modifiers/mixin/mixin_class_no_modifier_inside_library_error_test.dart

@@ -0,0 +1,45 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// SharedOptions=--enable-experiment=class-modifiers
+
+// Error when mixing in a regular class inside its library.
+
+class Class {
+  int foo = 0;
+}
+
+mixin Mixin {
+  int foo = 0;
+}
+
+abstract class A with Class {}
+// ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+class B with Class {}
+// ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+class C = Object with Class;
+// ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+abstract class D with Class, Mixin {}
+// ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+class E with Class, Mixin {}
+// ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+class NamedMixinClassApplication = Object with Class;
+// ^
+// [analyzer] unspecified
+// [cfe] unspecified

tests/language/class_modifiers/mixin/mixin_class_no_modifier_inside_library_test.dart

@@ -1,47 +0,0 @@
-// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-// SharedOptions=--enable-experiment=class-modifiers
-
-// Mixing in a regular class inside its library.
-
-import 'package:expect/expect.dart';
-
-class Class {
-  int foo = 0;
-}
-
-mixin Mixin {
-  int foo = 0;
-}
-
-abstract class A with Class {}
-
-class AImpl extends A {}
-
-class B with Class {}
-
-class C = Object with Class;
-
-abstract class D with Class, Mixin {}
-
-class DImpl extends D {}
-
-class E with Class, Mixin {}
-
-class NamedMixinClassApplication = Object with Mixin;
-
-class F with NamedMixinClassApplication {
-  // To avoid runtime error with DDC until issue 50489 is fixed.
-  int foo = 0;
-}
-
-main() {
-  Expect.equals(0, AImpl().foo);
-  Expect.equals(0, B().foo);
-  Expect.equals(0, C().foo);
-  Expect.equals(0, DImpl().foo);
-  Expect.equals(0, E().foo);
-  Expect.equals(0, F().foo);
-}

tests/language/class_modifiers/mixin/mixin_class_part_lib.dart

@@ -11,7 +11,3 @@ part of 'mixin_class_part_test.dart';
 class A with MixinClass {}
 
 abstract class B with MixinClass {}
-
-class NonMixinClass {
-  int foo = 0;
-}

tests/language/class_modifiers/mixin/mixin_class_part_test.dart

@@ -16,10 +16,7 @@ mixin class MixinClass {
 
 class BImpl extends B {}
 
-class WithNonMixinClass with NonMixinClass {}
-
 main() {
   Expect.equals(0, A().foo);
   Expect.equals(0, BImpl().foo);
-  Expect.equals(0, WithNonMixinClass().foo);
 }

tests/language/class_modifiers/mixin/mixin_class_superclass_not_object_error_test.dart

@@ -7,9 +7,9 @@
 // Error when applying the mixin modifier to a class whose superclass is not
 // Object.
 
-class NotObject {}
+mixin class NotObject {}
 
-class AlsoNotObject {}
+mixin class AlsoNotObject {}
 
 mixin class MixinClass extends NotObject {}
 //                             ^^^^^^^^^

tests/language/sealed_class/sealed_class_as_mixin_in_lib_test.dart

@@ -1,47 +0,0 @@
-// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-// SharedOptions=--enable-experiment=sealed-class,class-modifiers
-
-// Allow mixing in a sealed class inside of library.
-
-import "package:expect/expect.dart";
-
-sealed class SealedClass {
-  int foo = 0;
-}
-sealed mixin SealedMixin {}
-class Class {
-  int foo = 0;
-}
-mixin Mixin {}
-
-abstract class A with SealedClass {}
-
-class AImpl extends A {}
-
-class B with SealedClass {}
-
-abstract class C = Object with SealedClass;
-
-class CImpl extends C {}
-
-abstract class D with SealedClass, Class {}
-
-class DImpl extends D {}
-
-class E with Class, SealedMixin {}
-
-abstract class F with Mixin, SealedClass {}
-
-class FImpl extends F {}
-
-main() {
-  Expect.equals(0, AImpl().foo);
-  Expect.equals(0, B().foo);
-  Expect.equals(0, CImpl().foo);
-  Expect.equals(0, DImpl().foo);
-  Expect.equals(0, E().foo);
-  Expect.equals(0, FImpl().foo);
-}