[test_runner] Support static error test expectations in augmentation libraries.

R=eernst@google.com

Change-Id: I52fd157be6ba561f571170ce393d80820b2744dc
Bug: https://github.com/dart-lang/sdk/issues/44990
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/356401
Reviewed-by: Erik Ernst <eernst@google.com>
Auto-Submit: Morgan :) <davidmorgan@google.com>
Commit-Queue: Morgan :) <davidmorgan@google.com>

pkg/test_runner/lib/src/test_file.dart

@@ -14,7 +14,7 @@ final _environmentRegExp = RegExp(r"// Environment=(.*)");
 final _packagesRegExp = RegExp(r"// Packages=(.*)");
 final _experimentRegExp = RegExp(r"^--enable-experiment=([a-z0-9,-]+)$");
 final _localFileRegExp = RegExp(
-    r"""^\s*(?:import|part) ['"](?!package|dart)(.*)['"];""",
+    r"""^\s*(?:import(?: augment)?|part) ['"](?!package:|dart:)(.*)['"];""",
     multiLine: true);
 
 List<String> _splitWords(String s) =>

tests/language/test_runner/impl/imported_augmentation_library.dart

@@ -0,0 +1,12 @@
+// Copyright (c) 2024, 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=macros
+
+library augment '../imported_augmentation_library_failure_test.dart';
+
+class A
+//    ^
+// [analyzer] SYNTACTIC_ERROR.EXPECTED_BODY
+// [cfe] A class declaration must have a body, even if it is empty.
+

tests/language/test_runner/imported_augmentation_library_failure_test.dart

@@ -0,0 +1,8 @@
+// Copyright (c) 2024, 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=macros
+
+// Static tests can assert on failures in imported augmentation libraries.
+
+import augment 'impl/imported_augmentation_library.dart';