Introduce LibraryUpdater.

dart/tests/try/poi/compiler_test_case.dart

+// Copyright (c) 2014, 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.
+
+// Helper class for writing compiler tests.
+library trydart.compiler_test_case;
+
+import 'dart:async' show
+    Future;
+
+export 'dart:async' show
+    Future;
+
+import 'package:async_helper/async_helper.dart' show
+    asyncTest;
+
+import '../../compiler/dart2js/compiler_helper.dart' show
+    MockCompiler,
+    compilerFor;
+
+export 'package:expect/expect.dart' show
+    Expect;
+
+const String SCHEME = 'org.trydart.compiler-test-case';
+
+Uri customUri(String path) => Uri.parse('$SCHEME://$path');
+
+Future runTests(List<CompilerTest> tests) {
+  asyncTest(() => Future.forEach(tests, runTest));
+}
+
+Future runTest(CompilerTestCase test) {
+  print('\n{{{\n$test\n\n=== Test Output:\n');
+  return test.run().then((_) {
+  print('}}}');
+  });
+}
+
+abstract class CompilerTestCase {
+  final String source;
+
+  final Uri scriptUri;
+
+  final MockCompiler compiler;
+
+  Future<LibraryElement> mainAppCache;
+
+  CompilerTestCase.init(this.source, this.scriptUri, this.compiler);
+
+  CompilerTestCase.intermediate(String source, Uri scriptUri)
+      : this.init(source, scriptUri, compilerFor(source, scriptUri));
+
+  CompilerTestCase(String source, [String path])
+      : this.intermediate(source, customUri(path == null ? 'main.dart' : path));
+
+  Future<LibraryElement> get mainApp {
+    if (mainAppCache == null) {
+      mainAppCache = compiler.libraryLoader.loadLibrary(scriptUri);
+    }
+    return mainAppCache;
+  }
+
+  Future run();
+
+  String toString() => source;
+}