Use the new test runner.

lib/src/io.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.
 
 /// Helper functionality to make working with IO easier.
 library pub.io;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
@@ skipping 464 matching lines @@
   createSymlink(target, symlink, relative: relative);
 }
 
 /// Whether the current process is one of pub's test files.
 ///
 /// This works because an actual pub executable that imports this will always
 /// start with "pub".
 final bool runningAsTest =
     !path.url.basename(Platform.script.path).startsWith('pub.');
 
+// TODO(nweiz): Use the test API when test#48 is fixed.
+/// Whether the current process is one of pub's test files being run through the
+/// test package's test runner.
+///
+/// The test runner starts all tests from an entrypoint called
+/// "runInIsolate.dart'>
+final bool runningAsTestRunner =
+    path.url.basename(Platform.script.path).startsWith('runInIsolate.dart');
+
 /// Whether the current process is a pub subprocess being run from a test.
 ///
 /// The "_PUB_TESTING" variable is automatically set for all the test code's
 /// invocations of pub.
 final bool runningFromTest = Platform.environment.containsKey('_PUB_TESTING');
 
 /// Whether pub is running from within the Dart SDK, as opposed to from the Dart
 /// source repository.
 final bool runningFromSdk =
     !runningFromTest && Platform.script.path.endsWith('.snapshot');
@@ skipping 33 matching lines @@
 }
 
 /// The path to the root of pub's sources in the pub repo.
 ///
 /// This throws a [StateError] if it's called when running pub from the SDK.
 final String pubRoot = (() {
   if (runningFromSdk) {
     throw new StateError("Can't get pub's root from the SDK.");
   }
 
+  // The test runner always runs from the working directory.
+  if (runningAsTestRunner) return path.current;
+
   var script = path.fromUri(Platform.script);
   if (runningAsTest) {
     // Running from "test/../some_test.dart".
     var components = path.split(script);
     var testIndex = components.indexOf("test");
     if (testIndex == -1) throw new StateError("Can't find pub's root.");
     return path.joinAll(components.take(testIndex));
   }
 
   // Pub is either run from ".pub/pub.test.snapshot" or "bin/pub.dart".
@@ skipping 517 matching lines @@
 
   // TODO(rnystrom): Remove this and change to returning one string.
   static List<String> _toLines(String output) {
     var lines = splitLines(output);
     if (!lines.isEmpty && lines.last == "") lines.removeLast();
     return lines;
   }
 
   bool get success => exitCode == exit_codes.SUCCESS;
 }