Add support for --pub-serve.

lib/src/util/io.dart

 // Copyright (c) 2015, 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.
 
 library test.util.io;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:mirrors';
 
 import 'package:path/path.dart' as p;
+import 'package:pub_semver/pub_semver.dart';
 
 import '../backend/operating_system.dart';
 import '../runner/load_exception.dart';
 
 /// The root directory of the Dart SDK.
 final String sdkDir =
     p.dirname(p.dirname(Platform.executable));
 
+/// The version of the Dart SDK currently in use.

[kevmoo, 2015/04/03 22:55:53]

Annoying nit: if this check fails, an exception will thrown the first time – and
null will be returned every time after

If the check is catastrophic to the runner, that's fine. If not, we could end up
with weird NPE errors mixed in with one stack trace with something that could
actually be debugged

+final Version _sdkVersion = new Version.parse(
+    new File(p.join(p.dirname(p.dirname(Platform.executable)), 'version'))
+        .readAsStringSync().trim());
+
 /// Returns the current operating system.
 final OperatingSystem currentOS = (() {
   var name = Platform.operatingSystem;
   var os = OperatingSystem.findByIoName(name);
   if (os != null) return os;
 
   throw new UnsupportedError('Unsupported operating system "$name".');
 })();
 
 /// The path to the `lib` directory of the `test` package.
 String libDir({String packageRoot}) {
   var pathToIo = libraryPath(#test.util.io, packageRoot: packageRoot);
   return p.dirname(p.dirname(p.dirname(pathToIo)));
 }
 
 /// Returns whether the current Dart version supports [Isolate.kill].
 final bool supportsIsolateKill = _supportsIsolateKill;
 bool get _supportsIsolateKill {
   // This isn't 100% accurate, since early 1.9 dev releases didn't support
   // Isolate.kill(), but it's very unlikely anyone will be using them.
   // TODO(nweiz): remove this when we no longer support older Dart versions.
-  var path = p.join(p.dirname(p.dirname(Platform.executable)), 'version');
-  return !new File(path).readAsStringSync().startsWith('1.8');
+  return new VersionConstraint.parse('>=1.9.0-dev <2.0.0').allows(_sdkVersion);
+}
+
+/// Returns whether the current Dart version has a fix for issue 23084.
+final bool supportsPubServe = _supportsPubServe;
+bool get _supportsPubServe {
+  // This isn't 100% accurate, since issue 23084 wasn't fixed in early 1.10 dev
+  // releases, but it's unlikely anyone will be using them.
+  // TODO(nweiz): remove this when we no longer support older Dart versions.
+  return new VersionConstraint.parse('>=1.9.2 <2.0.0').allows(_sdkVersion);
 }
 
 // TODO(nweiz): Make this check [stdioType] once that works within "pub run".
 /// Whether "special" strings such as Unicode characters or color escapes are
 /// safe to use.
 ///
 /// On Windows or when not printing to a terminal, only printable ASCII
 /// characters should be used.
 bool get canUseSpecialChars =>
     Platform.operatingSystem != 'windows' &&
@@ skipping 54 matching lines @@
 /// returned.
 String libraryPath(Symbol libraryName, {String packageRoot}) {
   var lib = currentMirrorSystem().findLibrary(libraryName);
   if (lib.uri.scheme != 'package') return p.fromUri(lib.uri);
 
   // TODO(nweiz): is there a way to avoid assuming this is being run next to a
   // packages directory?.
   if (packageRoot == null) packageRoot = p.absolute('packages');
   return p.join(packageRoot, p.fromUri(lib.uri.path));
 }