#3180. Add @staticInterop tests. Part 1.

LibTest/js_interop/staticInterop_A01_t01.dart

@@ -0,0 +1,27 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `staticInterop` enables the JS annotated class to be treated as
+/// a "static" interop class.
+///
+/// These classes allow interop with native types, like the ones in `dart:html`.
+/// These classes should not contain any instance members, inherited or
+/// otherwise, and should instead use static extension members.
+///
+/// @description Checks it is a compile-time error if a class is annotated with
+/// `@staticInterop` but has no `@JS()` annotation.
+/// @author sgrekhov22@gmail.com
+
+import 'dart:js_interop';
+
+@staticInterop
+class C {
+//    ^
+// [analyzer] unspecified
+// [web] unspecified
+}
+
+main() {
+  print(C);
+}

LibTest/js_interop/staticInterop_A01_t02.dart

@@ -0,0 +1,38 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `staticInterop` enables the JS annotated class to be treated as
+/// a "static" interop class.
+///
+/// These classes allow interop with native types, like the ones in `dart:html`.
+/// These classes should not contain any instance members, inherited or
+/// otherwise, and should instead use static extension members.
+///
+/// @description Checks it is a compile-time error if an enum is annotated with
+/// `@staticInterop`.
+/// @author sgrekhov22@gmail.com
+
+import 'dart:js_interop';
+
+@staticInterop
+enum E1 {
+//   ^^
+// [analyzer] unspecified
+// [web] unspecified
+  e0;
+}
+
+@staticInterop
+@JS()
+enum E2 {
+//   ^^
+// [analyzer] unspecified
+// [web] unspecified
+  e0;
+}
+
+main() {
+  print(E1);
+  print(E2);
+}

LibTest/js_interop/staticInterop_A01_t03.dart

@@ -0,0 +1,34 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `staticInterop` enables the JS annotated class to be treated as
+/// a "static" interop class.
+///
+/// These classes allow interop with native types, like the ones in `dart:html`.
+/// These classes should not contain any instance members, inherited or
+/// otherwise, and should instead use static extension members.
+///
+/// @description Checks that it is a compile-time error if an extension is
+/// annotated with `@staticInterop`.
+/// @author sgrekhov22@gmail.com
+/// @issue 61119, 61124
+
+import 'dart:js_interop';
+
+class C {}
+
+@staticInterop
+@JS()
+extension Ext on C {
+//        ^^^
+// [analyzer] unspecified
+// [web] unspecified
+  external String getString();
+  external int getNumber();
+  external bool getBool();
+}
+
+main() {
+  print(C);
+}

LibTest/js_interop/staticInterop_A01_t04.dart

@@ -0,0 +1,37 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `staticInterop` enables the JS annotated class to be treated as
+/// a "static" interop class.
+///
+/// These classes allow interop with native types, like the ones in `dart:html`.
+/// These classes should not contain any instance members, inherited or
+/// otherwise, and should instead use static extension members.
+///
+/// @description Checks that it is a warning if a mixin is annotated with
+/// `@staticInterop`.
+/// @author sgrekhov22@gmail.com
+/// @issue 61124
+
+import 'dart:js_interop';
+
+@staticInterop
+mixin M1 {
+//    ^^
+// [analyzer] unspecified
+// [web] unspecified
+}
+
+@staticInterop
+@JS()
+mixin M2 {
+//    ^^
+// [analyzer] unspecified
+// [web] unspecified
+}
+
+main() {
+  print(M1);
+  print(M2);
+}

LibTest/js_interop/staticInterop_A01_t05.dart

@@ -0,0 +1,50 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `staticInterop` enables the JS annotated class to be treated as
+/// a "static" interop class.
+///
+/// These classes allow interop with native types, like the ones in `dart:html`.
+/// These classes should not contain any instance members, inherited or
+/// otherwise, and should instead use static extension members.
+///
+/// @description Checks that it is a warning if an extension type is annotated
+/// with `@staticInterop`.
+/// @author sgrekhov22@gmail.com
+/// @issue 61124
+
+import 'dart:js_interop';
+
+@staticInterop
+extension type ET1(JSObject o) {}
+//             ^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+@staticInterop
+@JS()
+extension type ET2(JSObject o) {}
+//             ^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+@staticInterop
+extension type ET3(JSObject o) implements JSObject {}
+//             ^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+@staticInterop
+@JS()
+extension type ET4(JSObject o) implements JSObject {}
+//             ^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+main() {
+  print(ET1);
+  print(ET2);
+  print(ET3);
+  print(ET4);
+}

LibTest/js_interop/staticInterop_A01_t06.dart

@@ -0,0 +1,48 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `staticInterop` enables the JS annotated class to be treated as
+/// a "static" interop class.
+///
+/// These classes allow interop with native types, like the ones in `dart:html`.
+/// These classes should not contain any instance members, inherited or
+/// otherwise, and should instead use static extension members.
+///
+/// @description Checks that it is a warning if a declaration that isn't a JS
+/// interop class is annotated with `@staticInterop`.
+/// @author sgrekhov22@gmail.com
+/// @issue 61124
+
+import 'dart:js_interop';
+
+@staticInterop
+int variable = 42;
+//  ^^^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+@staticInterop
+String get getter => "getter";
+//         ^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+@staticInterop
+String func() => "function";
+//     ^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+@staticInterop
+void set setter(String _) {}
+//       ^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+main() {
+  print(variable);
+  print(getter);
+  print(func);
+  setter = "";
+}

LibTest/js_interop/staticInterop_A01_t07.dart

@@ -0,0 +1,31 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `staticInterop` enables the JS annotated class to be treated as
+/// a "static" interop class.
+///
+/// These classes allow interop with native types, like the ones in `dart:html`.
+/// These classes should not contain any instance members, inherited or
+/// otherwise, and should instead use static extension members.
+///
+/// @description Checks that it is a warning if a local declaration is annotated
+/// with `@staticInterop`.
+/// @author sgrekhov22@gmail.com
+/// @issue 61124
+
+import 'dart:js_interop';
+
+main() {
+  @staticInterop
+  int variable = 42;
+//    ^^^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+  @staticInterop
+  String func() => "function";
+//       ^^^^
+// [analyzer] unspecified
+// [web] unspecified
+}

LibTest/js_interop/staticInterop_A01_t08.dart

@@ -0,0 +1,83 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `staticInterop` enables the JS annotated class to be treated as
+/// a "static" interop class.
+///
+/// These classes allow interop with native types, like the ones in `dart:html`.
+/// These classes should not contain any instance members, inherited or
+/// otherwise, and should instead use static extension members.
+///
+/// @description Checks that it is a warning if a class member is annotated with
+/// `@staticInterop`.
+/// @author sgrekhov22@gmail.com
+/// @issue 61124
+
+import 'dart:js_interop';
+
+class C {
+  @staticInterop
+  C();
+//^
+// [analyzer] unspecified
+// [web] unspecified
+
+  @staticInterop
+  factory C.f() = C;
+//        ^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+  @staticInterop
+  int instanceVariable = 42;
+//    ^^^^^^^^^^^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+  @staticInterop
+  String get instanceGetter => "instanceGetter";
+//           ^^^^^^^^^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+  @staticInterop
+  String instanceMethod() => "instanceMethod";
+//       ^^^^^^^^^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+  @staticInterop
+  void set instanceSetter(String _) {}
+//         ^^^^^^^^^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+  @staticInterop
+  static int staticVariable = 42;
+//           ^^^^^^^^^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+  @staticInterop
+  static String get staticGetter => "staticGetter";
+//                  ^^^^^^^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+  @staticInterop
+  static String staticMethod() => "staticMethod";
+//              ^^^^^^^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+
+  @staticInterop
+  static void set staticSetter(String _) {}
+//                ^^^^^^^^^^^^
+// [analyzer] unspecified
+// [web] unspecified
+}
+
+main() {
+  print(C);
+}