#2825. Add tests for resolving extensions (#3360)

Add tests for resolving extensions

Author: sgrekhov

LanguageFeatures/Parts-with-imports/resolving_extensions_A01_t01.dart

@@ -0,0 +1,40 @@
+// 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 With this feature, imports are not global to the entire library,
+/// and neither is extension availability.
+///
+/// Extension availability is defined per file, and an extension is available in
+/// a Dart file if any of:
+/// - The extension is declared by the library of the Dart file.
+/// - The extension is available by import in the Dart file.
+/// where an extension is available by import in a Dart file if any of:
+/// - That file contains an import directive which imports the extension.
+/// - That file is a part file and the extension is (recursively) available by
+///   import in its parent file.
+///
+/// @description Check that an extension declared in a part file is available in
+/// its parent file and vice versa.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enhanced-parts
+
+import '../../Utils/expect.dart';
+
+part 'resolving_extensions_A01_t01_part1.dart';
+
+class A {}
+
+extension on A {
+  String get id => "extension from root";
+}
+
+class C {}
+
+main() {
+  Expect.equals("extension from part1", C().getId());
+  Expect.equals("extension from part2", C().getId2());
+  testPart1();
+  testPart2();
+}

LanguageFeatures/Parts-with-imports/resolving_extensions_A01_t01_part1.dart

@@ -0,0 +1,33 @@
+// 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 With this feature, imports are not global to the entire library,
+/// and neither is extension availability.
+///
+/// Extension availability is defined per file, and an extension is available in
+/// a Dart file if any of:
+/// - The extension is declared by the library of the Dart file.
+/// - The extension is available by import in the Dart file.
+/// where an extension is available by import in a Dart file if any of:
+/// - That file contains an import directive which imports the extension.
+/// - That file is a part file and the extension is (recursively) available by
+///   import in its parent file.
+///
+/// @description Check that an extension declared in a part file is available in
+/// its parent file and vice versa.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enhanced-parts
+
+part of 'resolving_extensions_A01_t01.dart';
+part 'resolving_extensions_A01_t01_part2.dart';
+
+extension on C {
+  String getId() => "extension from part1";
+}
+
+testPart1() {
+  Expect.equals("extension from root", A().id);
+  Expect.equals("extension from part2", C().getId2());
+}

LanguageFeatures/Parts-with-imports/resolving_extensions_A01_t01_part2.dart

@@ -0,0 +1,32 @@
+// 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 With this feature, imports are not global to the entire library,
+/// and neither is extension availability.
+///
+/// Extension availability is defined per file, and an extension is available in
+/// a Dart file if any of:
+/// - The extension is declared by the library of the Dart file.
+/// - The extension is available by import in the Dart file.
+/// where an extension is available by import in a Dart file if any of:
+/// - That file contains an import directive which imports the extension.
+/// - That file is a part file and the extension is (recursively) available by
+///   import in its parent file.
+///
+/// @description Check that an extension declared in a part file is available in
+/// its parent file and vice versa.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enhanced-parts
+
+part of 'resolving_extensions_A01_t01_part1.dart';
+
+extension on A {
+  String getId2() => "extension from part2";
+}
+
+testPart2() {
+  Expect.equals("extension from root", A().id);
+  Expect.equals("extension from part1", C().getId());
+}

LanguageFeatures/Parts-with-imports/resolving_extensions_A01_t02.dart

@@ -0,0 +1,39 @@
+// 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 With this feature, imports are not global to the entire library,
+/// and neither is extension availability.
+///
+/// Extension availability is defined per file, and an extension is available in
+/// a Dart file if any of:
+/// - The extension is declared by the library of the Dart file.
+/// - The extension is available by import in the Dart file.
+/// where an extension is available by import in a Dart file if any of:
+/// - That file contains an import directive which imports the extension.
+/// - That file is a part file and the extension is (recursively) available by
+///   import in its parent file.
+///
+/// @description Check that an extension declared in a part file is available in
+/// its parent file and it is a compile-time error if extensions conflict.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enhanced-parts
+
+part 'resolving_extensions_A01_t02_part1.dart';
+
+class C {}
+
+extension on C {
+  String getId() => "extension defined in this file";
+  String get id => "extension defined in this file";
+}
+
+main() {
+  C().getId();
+//    ^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  C().id; // Ok
+}

LanguageFeatures/Parts-with-imports/resolving_extensions_A01_t02_part1.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 With this feature, imports are not global to the entire library,
+/// and neither is extension availability.
+///
+/// Extension availability is defined per file, and an extension is available in
+/// a Dart file if any of:
+/// - The extension is declared by the library of the Dart file.
+/// - The extension is available by import in the Dart file.
+/// where an extension is available by import in a Dart file if any of:
+/// - That file contains an import directive which imports the extension.
+/// - That file is a part file and the extension is (recursively) available by
+///   import in its parent file.
+///
+/// @description Check that an extension declared in a part file is available in
+/// its parent file and it is a compile-time error if extensions conflict.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enhanced-parts
+
+part of 'resolving_extensions_A01_t02.dart';
+
+extension on C {
+  String getId() => "extension from part";
+}

LanguageFeatures/Parts-with-imports/resolving_extensions_A01_t03.dart

@@ -0,0 +1,39 @@
+// 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 With this feature, imports are not global to the entire library,
+/// and neither is extension availability.
+///
+/// Extension availability is defined per file, and an extension is available in
+/// a Dart file if any of:
+/// - The extension is declared by the library of the Dart file.
+/// - The extension is available by import in the Dart file.
+/// where an extension is available by import in a Dart file if any of:
+/// - That file contains an import directive which imports the extension.
+/// - That file is a part file and the extension is (recursively) available by
+///   import in its parent file.
+///
+/// @description Check that an extension available by import in a part file is
+/// available in its parts but not available in the parent.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enhanced-parts
+
+import '../../Utils/expect.dart';
+
+part 'resolving_extensions_A01_t03_part1.dart';
+
+class C {}
+
+extension Ext on Object {
+  String get id => "Extension Ext";
+}
+
+main() {
+  testPart1();
+  testPart2();
+  // If there is no conflict with the LibExt extension imported in _part1, that
+  // means LibExt is not available here.
+  Expect.equals("Extension Ext", C().id);
+}

LanguageFeatures/Parts-with-imports/resolving_extensions_A01_t03_part1.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 With this feature, imports are not global to the entire library,
+/// and neither is extension availability.
+///
+/// Extension availability is defined per file, and an extension is available in
+/// a Dart file if any of:
+/// - The extension is declared by the library of the Dart file.
+/// - The extension is available by import in the Dart file.
+/// where an extension is available by import in a Dart file if any of:
+/// - That file contains an import directive which imports the extension.
+/// - That file is a part file and the extension is (recursively) available by
+///   import in its parent file.
+///
+/// @description Check that an extension available by import in a part file is
+/// available in its parts.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enhanced-parts
+
+part of 'resolving_extensions_A01_t03.dart';
+
+import 'resolving_extensions_lib.dart';
+
+part 'resolving_extensions_A01_t03_part2.dart';
+
+testPart1() {
+  Expect.equals("extension LibExt", C().id);
+}

LanguageFeatures/Parts-with-imports/resolving_extensions_A01_t03_part2.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 With this feature, imports are not global to the entire library,
+/// and neither is extension availability.
+///
+/// Extension availability is defined per file, and an extension is available in
+/// a Dart file if any of:
+/// - The extension is declared by the library of the Dart file.
+/// - The extension is available by import in the Dart file.
+/// where an extension is available by import in a Dart file if any of:
+/// - That file contains an import directive which imports the extension.
+/// - That file is a part file and the extension is (recursively) available by
+///   import in its parent file.
+///
+/// @description Check that an extension available by import in a part file is
+/// available in its parts.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enhanced-parts
+
+part of 'resolving_extensions_A01_t03_part1.dart';
+
+testPart2() {
+  Expect.equals("extension LibExt", C().id);
+}

LanguageFeatures/Parts-with-imports/resolving_extensions_A01_t04.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 With this feature, imports are not global to the entire library,
+/// and neither is extension availability.
+///
+/// Extension availability is defined per file, and an extension is available in
+/// a Dart file if any of:
+/// - The extension is declared by the library of the Dart file.
+/// - The extension is available by import in the Dart file.
+/// where an extension is available by import in a Dart file if any of:
+/// - That file contains an import directive which imports the extension.
+/// - That file is a part file and the extension is (recursively) available by
+///   import in its parent file.
+///
+/// @description Check that an extension available by import in a part file is
+/// not available in its parent.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enhanced-parts
+
+part 'resolving_extensions_A01_t04_part1.dart';
+
+class C {}
+
+main() {
+  C().id;
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  testPart1();
+  testPart2();
+}

LanguageFeatures/Parts-with-imports/resolving_extensions_A01_t04_part1.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 With this feature, imports are not global to the entire library,
+/// and neither is extension availability.
+///
+/// Extension availability is defined per file, and an extension is available in
+/// a Dart file if any of:
+/// - The extension is declared by the library of the Dart file.
+/// - The extension is available by import in the Dart file.
+/// where an extension is available by import in a Dart file if any of:
+/// - That file contains an import directive which imports the extension.
+/// - That file is a part file and the extension is (recursively) available by
+///   import in its parent file.
+///
+/// @description Check that an extension available by import in a part file is
+/// not available in its parent.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enhanced-parts
+
+part of 'resolving_extensions_A01_t04.dart';
+
+import 'resolving_extensions_lib.dart';
+
+part 'resolving_extensions_A01_t04_part2.dart';
+
+testPart1() {
+  C().id; // Ok
+}