Testable patch parser.

dart/tests/compiler/dart2js/patch2_test.dart

+// Copyright (c) 2013, 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 "mock_compiler.dart";
+
+import "../../../sdk/lib/_internal/compiler/implementation/elements/elements.dart"
+    show Element, FunctionElement;
+import "../../../sdk/lib/_internal/compiler/implementation/patch_parser.dart";
+import "../../../sdk/lib/_internal/compiler/implementation/scanner/scannerlib.dart"
+    show StringScanner;
+import "../../../sdk/lib/_internal/compiler/implementation/util/util.dart";
+
+class TestPatchElementListener extends PatchElementListener {
+  TestPatchElementListener(compiler, unit)
+    : super(compiler, unit, compiler.getNextFreeClassId, new LinkBuilder());
+
+  void applyPatch(Element patch) {
+  }
+}
+
+Element buildElement(MockCompiler compiler, String source) {
+  var library = compiler.createLibrary('origin', 'external foo();');
+  var elements = library.localMembers.toList();
+  Expect.equals(1, elements.length);
+  return elements[0];
+}
+
+Element buildPatchElement(MockCompiler compiler, String source) {
+  var library = compiler.createUnparsedLibrary('patch', source);
+  var unit = library.entryCompilationUnit;
+
+  var tokens = new StringScanner(source).tokenize();
+  var listener = new TestPatchElementListener(compiler, unit);
+  new PatchParser(listener).parseUnit(tokens);
+
+  var elements = unit.localMembers.toList();
+  Expect.equals(1, elements.length);
+  Expect.isTrue(isPatchElement(elements[0]));
+  return elements[0];
+}
+
+main() {
+  MockCompiler compiler = new MockCompiler();
+  FunctionElement foo = buildElement(compiler, 'external foo();');
+  FunctionElement fooPatch = buildPatchElement(compiler, 'patch foo() {}');
+  patchElement(null, foo, fooPatch);
+}