Skeleton code for running the forthcoming async/await compiler on pub.

sdk/lib/_internal/pub/test/test_pub.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.
 
 /// Test infrastructure for testing pub.
 ///
 /// Unlike typical unit tests, most pub tests are integration tests that stage
 /// some stuff on the file system, run pub, and then validate the results. This
 /// library provides an API to build tests like that.
 library test_pub;
@@ skipping 458 matching lines @@
   pub.stdout.expect(emitsLines(
       "|-- LICENSE\n"
       "|-- lib\n"
       "|   '-- test_pkg.dart\n"
       "'-- pubspec.yaml\n"
       "\n"
       "Looks great! Are you ready to upload your package (y/n)?"));
   pub.writeLine("y");
 }
 
+/// Whether the async/await compiler has already been run.
+///
+/// If a test suite runs pub more than once, we only need to run the compiler
+/// the first time.
+// TODO(rnystrom): Remove this when #104 is fixed.
+bool _compiledAsync = false;
+
+/// Gets the path to the pub entrypoint Dart script to run.
+// TODO(rnystrom): This exists to run the async/await compiler on pub and then
+// get the path to the output of that. Once #104 is fixed, remove this.
+String _getPubPath(String dartBin) {
+  var buildDir = path.join(path.dirname(dartBin), '../../');
+
+  // Ensure the async/await compiler has been run once for this test suite. The
+  // compiler itself will only re-compile source files that have actually
+  // changed, so this is a no-op if everything is already compiled.
+  if (!_compiledAsync) {
+    var result = Process.runSync(dartBin, [
+      '--package-root=$_packageRoot/',
+      path.join(testDirectory, '..', 'bin', 'async_compile.dart'),
+      buildDir,
+      '--silent'
+    ]);
+    stdout.write(result.stdout);
+    stderr.write(result.stderr);
+    if (result.exitCode != 0) fail("Async/await compiler failed.");
+
+    _compiledAsync = true;
+  }
+
+  return path.join(buildDir, 'pub_async/bin/pub.dart');
+}
+
 /// Starts a Pub process and returns a [ScheduledProcess] that supports
 /// interaction with that process.
 ///
 /// Any futures in [args] will be resolved before the process is started.
 ScheduledProcess startPub({List args, Future<Uri> tokenEndpoint}) {
   String pathInSandbox(String relPath) {
     return path.join(path.absolute(sandboxDir), relPath);
   }
 
   ensureDir(pathInSandbox(appPath));
 
   // Find a Dart executable we can use to spawn. Use the same one that was
   // used to run this script itself.
   var dartBin = Platform.executable;
 
   // If the executable looks like a path, get its full path. That way we
   // can still find it when we spawn it with a different working directory.
   if (dartBin.contains(Platform.pathSeparator)) {
     dartBin = path.absolute(dartBin);
   }
 
   // Find the main pub entrypoint.
-  var pubPath = path.join(testDirectory, '..', 'bin', 'pub.dart');
+  var pubPath = _getPubPath(dartBin);
+  // TODO(rnystrom): Replace the above line with the following when #104 is
+  // fixed.
+  //var pubPath = path.join(testDirectory, '..', 'bin', 'pub.dart');
 
   var dartArgs = ['--package-root=$_packageRoot/', '--checked', pubPath,
       '--verbose'];
   dartArgs.addAll(args);
 
   if (tokenEndpoint == null) tokenEndpoint = new Future.value();
   var environmentFuture = tokenEndpoint.then((tokenEndpoint) {
     var environment = {};
     environment['_PUB_TESTING'] = 'true';
     environment['PUB_CACHE'] = pathInSandbox(cachePath);
@@ skipping 431 matching lines @@
         _lastMatcher.matches(item.last, matchState);
   }
 
   Description describe(Description description) {
     return description.addAll("(", ", ", ")", [_firstMatcher, _lastMatcher]);
   }
 }
 
 /// A [StreamMatcher] that matches multiple lines of output.
 StreamMatcher emitsLines(String output) => inOrder(output.split("\n"));