Add 'self_check' runtime for running self-checking unit tests

pkg/kernel/test/self_check_util.dart

+// Copyright (c) 2016, 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 '../bin/batch_util.dart';
+import 'dart:async';
+
+/// Wraps a main() method for a test that should be runnable as a self-checking
+/// unit test.
+///
+/// These tests can be run like:
+///
+///    tools/test.py -cdartk -rself_check
+///
+/// The test can either be run with a single file passed on the command line
+/// or run in batch mode.
+runSelfCheck(List<String> args, runTest(String filename)) {
+  Future<CompilerOutcome> batchMain(List<String> arguments) async {
+    if (arguments.length != 1) {
+      throw 'Exactly one argument expected';
+    }
+    String filename = arguments[0];
+    if (!filename.endsWith('.dill')) {
+      throw 'File does not have expected .dill extension: $filename';
+    }
+    runTest(filename);

[kustermann, 2016/12/06 10:39:05]

Maybe document if this [runTest] can ever be async (i.e. return a Future or not)
in the argument type.

[asgerf, 2016/12/06 13:42:08]

Good point. I've changed it to be asynchronous.

+    return CompilerOutcome.Ok;
+  }
+  if (args.length == 1 && args[0] == '--batch') {
+    runBatch(batchMain);
+  } else {
+    batchMain(args);
+  }
+}