Add a prefixes test for prefix references (#3837)

Author: srawlins

test/prefixes_test.dart

@@ -0,0 +1,51 @@
+// 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.
+
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import 'dartdoc_test_base.dart';
+import 'src/utils.dart';
+
+void main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(PrefixesTest);
+  });
+}
+
+@reflectiveTest
+class PrefixesTest extends DartdocTestBase {
+  @override
+  String get libraryName => 'prefixes';
+
+  void test_referenced() async {
+    var library = await bootPackageWithLibrary(
+      '''
+import 'dart:async' as async;
+
+/// Text [async].
+int x = 0;
+''',
+      additionalArguments: ['--link-to-remote'],
+    );
+    var f = library.properties.named('x');
+    // There is no link, but also no wrong link or crash.
+    expect(f.documentationAsHtml, '<p>Text <code>async</code>.</p>');
+  }
+
+  void test_referenced_wildcard() async {
+    var library = await bootPackageWithLibrary(
+      '''
+import 'dart:async' as _;
+
+/// Text [_].
+int x = 0;
+''',
+      additionalArguments: ['--link-to-remote'],
+    );
+    var f = library.properties.named('x');
+    // There is no link, but also no wrong link or crash.
+    expect(f.documentationAsHtml, '<p>Text <code>_</code>.</p>');
+  }
+}