Add (disabled) patch unit-test for dart2js.

tests/compiler/dart2js/patch_test.dart

+// Copyright (c) 2012, 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("../../../lib/compiler/implementation/leg.dart");
+#import("../../../lib/compiler/implementation/elements/elements.dart");
+#import("../../../lib/compiler/implementation/tree/tree.dart");
+#import("../../../lib/compiler/implementation/util/util.dart");
+#import("mock_compiler.dart");
+#import("parser_helper.dart");
+#import("dart:uri");
+
+Compiler applyPatch(String script, String patch) {
+  String core = "$DEFAULT_CORELIB\n$script";
+  MockCompiler compiler = new MockCompiler(coreSource: core);
+
+  var uri = new Uri("core.dartp");
+  var patchScript = new Script(uri, new MockFile(patch));
+  var patchLibrary = new LibraryElement(patchScript);
+
+  compiler.patchParser.scanLibraryElements(patchLibrary);
+  compiler.applyLibraryPatch(compiler.coreLibrary, patchLibrary);
+
+  return compiler;
+}
+
+Element ensure(compiler,
+               String name,
+               Element lookup(name),
+               [bool isPatched = true,
+                bool hasBody = false,
+                bool isGetter = false]) {
+  var element = lookup(buildSourceString(name));
+  Expect.isNotNull(element);
+  if (isGetter) {
+    Expect.isTrue(element is AbstractFieldElement);
+    Expect.isNotNull(element.getter);
+    element = element.getter;
+  }
+  if (element is! ContainerElement &&
+      element is! AbstractFieldElement) {
+    // Classes aren't patched like functions and variables are.
+    Expect.equals(isPatched, element.isPatched);
+  }
+  if (hasBody) {
+    var node = element.parseNode(compiler);
+    Expect.isNotNull(node, "Element isn't parseable, when a body was expected");
+    Expect.isNotNull(node.body, "expected body, bot none found");
+  }
+  return element;
+}
+
+testPatchFunction() {
+  var compiler = applyPatch(
+      "external test();",
+      "patch test() { return 'string'; } ");
+  ensure(compiler, "test", compiler.coreLibrary.find, hasBody: true);
+}
+
+testPatchMember() {
+  var compiler = applyPatch(
+      """
+      class Class {
+        external String toString();
+      }
+      """,
+      """
+      patch class Class {
+        patch String toString() => 'string';
+      }
+      """);
+  var container = ensure(compiler, "Class", compiler.coreLibrary.find);
+  ensure(compiler, "toString", container.lookupLocalMember, hasBody:true);
+}
+
+testPatchGetter() {
+  var compiler = applyPatch(
+      """
+      class Class {
+        external int get field();
+      }
+      """,
+      """
+      patch class Class {
+        patch int get field() => 5;
+      }
+      """);
+  var container = ensure(compiler, "Class", compiler.coreLibrary.find);
+  ensure(compiler,
+         "field",
+         container.lookupLocalMember,
+         isGetter: true,
+         hasBody: true);
+}
+
+testInjectFunction() {
+  var compiler = applyPatch(
+      "",
+      "int _function() => 5;");
+  ensure(compiler,
+         "_function",
+         compiler.coreLibrary.find,
+         hasBody: true,
+         isPatched: false);
+}
+
+main() {
+  testPatchFunction();
+  testPatchMember();
+  testPatchGetter();
+  testInjectFunction();
+}