Concept of how dart:mirrors LibraryMirror, ClassMirror can be implemented in dart2js.

tests/lib/mirrors/mirrors_test.dart

 // Copyright (c) 2011, 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.
 
 // TODO(rmacnak): Move the existing mirror tests here (a place for 
 // cross-implementation tests).
 
 library MirrorsTest;
 import "dart:mirrors";
-import "../../../pkg/unittest/lib/unittest.dart";
+
+import '../../compiler/dart2js_extra/async_helper.dart';
 
 var topLevelField;
 
 class Class {
   Class() { this.field = "default value"; }
   Class.withInitialValue(this.field);
   var field;
   static var staticField;
 }
 
-testFieldAccess(mirrors) {
+void testFieldAccess(mirrors) {
+  var dummyInstance = new Class.withInitialValue(123);
+
   var instance = new Class();
 
   var libMirror = mirrors.libraries["MirrorsTest"];
   var classMirror = libMirror.classes["Class"];
   var instMirror = reflect(instance);
 
-  libMirror.setField('topLevelField', 42);
-  var future = libMirror.getField('topLevelField');
-  future.then(expectAsync1((resultMirror) {
-    expect(resultMirror.reflectee, equals(42));
-    expect(topLevelField, equals(42));   
-  }));
+  asyncTest((onDone) {
+      libMirror.setField('topLevelField', 42).then(
+          (result) {
+            libMirror.getField('topLevelField').then(
+                (resultMirror) {
+                  Expect.equals(42, resultMirror.reflectee);
+                  Expect.equals(42, topLevelField);
+                  onDone(true);
+            });
+      });
+  });
   
-  classMirror.setField('staticField', 43);
-  future = classMirror.getField('staticField');
-  future.then(expectAsync1((resultMirror) {
-    expect(resultMirror.reflectee, equals(43));
-    expect(Class.staticField, equals(43)); 
-  }));
+  asyncTest((onDone) {
+      classMirror.setField('staticField', 43).then(
+          (result) {
+            classMirror.getField('staticField').then(
+                (resultMirror) {
+                  Expect.equals(43, resultMirror.reflectee);
+                  Expect.equals(43, Class.staticField);
+                  onDone(true);
+            });
+      });
+  });
 
-  instMirror.setField('field', 44);
-  future = instMirror.getField('field');
-  future.then(expectAsync1((resultMirror) {
-    expect(resultMirror.reflectee, equals(44));
-    expect(instance.field, equals(44)); 
-  }));
+  asyncTest((onDone) {
+      instMirror.setField('field', 44).then(
+          (result) {
+            instMirror.getField('field').then(
+                (resultMirror) {
+                  Expect.equals(44, resultMirror.reflectee);
+                  Expect.equals(44, instance.field);
+                  onDone(true);
+            });
+      });
+  });
 }
 
 testClosureMirrors(mirrors) {
   var closure = (x, y, z) { return x + y + z; };
   
   var mirror = reflect(closure);
-  expect(mirror is ClosureMirror, equals(true));
+  Expect.isTrue(mirror is ClosureMirror);
   
   var funcMirror = mirror.function;
-  expect(funcMirror is MethodMirror, equals(true));
-  expect(funcMirror.parameters.length, equals(3));
+  Expect.isTrue(funcMirror is MethodMirror);
+  Expect.equals(3, funcMirror.parameters.length);
 
-  var future = mirror.apply([2, 4, 8]);
-  future.then(expectAsync1((resultMirror) {
-    expect(resultMirror.reflectee, equals(14));
-  }));
+  asyncTest((onDone) {
+    mirror.apply([2, 4, 8]).then(
+        (resultMirror) {
+          Expect.equals(14, resultMirror.reflectee);
+          onDone(true);
+        });
+    });
 }
 
 testInvokeConstructor(mirrors) {
   var libMirror = mirrors.libraries["MirrorsTest"];
   var classMirror = libMirror.classes["Class"];
   
-  var future = classMirror.newInstance('', []);
-  future.then(expectAsync1((resultMirror) {
-    var instance = resultMirror.reflectee;
-    expect(instance is Class, equals(true));
-    expect(instance.field, equals("default value"));
-  }));
+  asyncTest((onDone) {
+    classMirror.newInstance('', []).then(
+        (resultMirror) {
+          var instance = resultMirror.reflectee;
+          Expect.isTrue(instance is Class);
+          Expect.equals("default value", instance.field);
+          onDone(true);
+        });
+    });
 
-  future = classMirror.newInstance('withInitialValue', [45]);
-  future.then(expectAsync1((resultMirror) {
-    var instance = resultMirror.reflectee;
-    expect(instance is Class, equals(true));
-    expect(instance.field, equals(45));
-  }));
+  asyncTest((onDone) {
+    classMirror.newInstance('withInitialValue', [45]).then(
+        (resultMirror) {
+          var instance = resultMirror.reflectee;
+          Expect.isTrue(instance is Class);
+          Expect.equals(45, instance.field);
+          onDone(true);
+        });
+  });
 }
 
 main() {
+  print("""
+
+This program is using an experimental feature called \"mirrors\".  As
+currently implemented, mirrors do not work with minification, and will
+cause spurious errors depending on how code was optimized.
+
+The authors of this program are aware of these problems and have
+decided the thrill of using an experimental feature is outweighing the
+risks.  Furthermore, the authors of this program understand that
+long-term, to fix the problems mentioned above, mirrors may have
+negative impact on size and performance of Dart programs compiled to
+JavaScript.
+""");
+
   var mirrors = currentMirrorSystem();
 
-  test("Test field access", () { testFieldAccess(mirrors); });
-  test("Test closure mirrors", () { testClosureMirrors(mirrors); });
-  test("Test invoke constructor", () { testInvokeConstructor(mirrors); });
+  testFieldAccess(mirrors);
+  testClosureMirrors(mirrors);
+  testInvokeConstructor(mirrors);
 }