Make sure to drain stderr in tests so that spawned process doesn't hang.

utils/tests/pub/test_pub.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.
 
 /**
  * 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.
  */
@@ skipping 1250 matching lines @@
     return Entrypoint.load(join(sandboxDir, appPath), cache)
         .chain((entrypoint) {
       var validator = fn(entrypoint);
       return validator.validate().transform((_) {
         return new Pair(validator.errors, validator.warnings);
       });
     });
   });
 }
 
-/// A matcher that matches a Pair.      
+/// A matcher that matches a Pair.
 Matcher pairOf(Matcher firstMatcher, Matcher lastMatcher) =>
    new _PairMatcher(firstMatcher, lastMatcher);
 
 class _PairMatcher extends BaseMatcher {
   final Matcher _firstMatcher;
   final Matcher _lastMatcher;
 
   _PairMatcher(this._firstMatcher, this._lastMatcher);
 
   bool matches(item, MatchState matchState) {
@@ skipping 45 matching lines @@
   /// Whether the user has scheduled the end of this process by calling either
   /// [shouldExit] or [kill].
   bool _endScheduled = false;
 
   /// Whether the process is expected to terminate at this point.
   bool _endExpected = false;
 
   /// Wraps a [Process] [Future] in a scheduled process.
   ScheduledProcess(this.name, Future<Process> process)
     : _process = process,
-      _stdout = process.transform((p) => new StringInputStream(p.stdout)),
-      _stderr = process.transform((p) => new StringInputStream(p.stderr)) {
+      _stdout = process.transform((p) => _wrapStream(p.stdout)),
+      _stderr = process.transform((p) => _wrapStream(p.stderr)) {
 
     _schedule((_) {
       if (!_endScheduled) {
         throw new StateError("Scheduled process $name must have shouldExit() "
             "or kill() called before the test is run.");
       }
 
       return _process.transform((p) {
         p.onExit = (c) {
           if (_endExpected) {
@@ skipping 110 matching lines @@
       _endExpected = true;
       return timeout(_exitCode, _SCHEDULE_TIMEOUT,
           "waiting for process $name to exit").transform((exitCode) {
         if (expectedExitCode != null) {
           expect(exitCode, equals(expectedExitCode));
         }
       });
     });
   }
 
+  /// Wraps [source] and ensures it gets eagerly drained. We do this to make
+  /// sure a process will exit even if we don't care about its output.
+  static Future<StringInputStream> _wrapStream(InputStream source) {
+    return new StringInputStream(wrapInputStream(source));
+  }
+
   /// Prints the remaining data in the process's stdout and stderr streams.
   /// Prints nothing if the straems are empty.
   Future _printStreams() {
     Future printStream(String streamName, StringInputStream stream) {
       return consumeStringInputStream(stream).transform((output) {
         if (output.isEmpty) return;
 
         print('\nProcess $name $streamName:');
         for (var line in output.trim().split("\n")) {
           print('| $line');
@@ skipping 152 matching lines @@
 /// calling [completion] is unnecessary.
 void expectLater(Future actual, matcher, {String reason,
     FailureHandler failureHandler, bool verbose: false}) {
   _schedule((_) {
     return actual.transform((value) {
       expect(value, matcher, reason: reason, failureHandler: failureHandler,
           verbose: false);
     });
   });
 }