Revert "Use scheduled_test for Pub tests."

utils/tests/pub/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;
 
 import 'dart:async';
 import 'dart:collection' show Queue;
 import 'dart:io';
 import 'dart:json' as json;
 import 'dart:math';
 import 'dart:uri';
 import 'dart:utf';
 
 import '../../../pkg/http/lib/testing.dart';
 import '../../../pkg/oauth2/lib/oauth2.dart' as oauth2;
 import '../../../pkg/pathos/lib/path.dart' as path;
-import '../../../pkg/scheduled_test/lib/scheduled_process.dart';
-import '../../../pkg/scheduled_test/lib/scheduled_server.dart';
-import '../../../pkg/scheduled_test/lib/scheduled_test.dart';
+import '../../../pkg/unittest/lib/unittest.dart';
 import '../../../pkg/yaml/lib/yaml.dart';
-
 import '../../lib/file_system.dart' as fs;
 import '../../pub/entrypoint.dart';
 // TODO(rnystrom): Using "gitlib" as the prefix here is ugly, but "git" collides
 // with the git descriptor method. Maybe we should try to clean up the top level
 // scope a bit?
 import '../../pub/git.dart' as gitlib;
 import '../../pub/git_source.dart';
 import '../../pub/hosted_source.dart';
 import '../../pub/http.dart';
 import '../../pub/io.dart';
 import '../../pub/path_source.dart';
 import '../../pub/safe_http_server.dart';
 import '../../pub/system_cache.dart';
 import '../../pub/utils.dart';
 import '../../pub/validator.dart';
 import 'command_line_config.dart';
-import 'descriptor.dart' as d;
 
 /// This should be called at the top of a test file to set up an appropriate
 /// test configuration for the machine running the tests.
 initConfig() {
   // If we aren't running on the bots, use the human-friendly config.
   if (new Options().arguments.contains('--human')) {
     configure(new CommandLineConfiguration());
   }
 }
 
+/// Creates a new [FileDescriptor] with [name] and [contents].
+FileDescriptor file(Pattern name, String contents) =>
+    new FileDescriptor(name, contents);
+
+/// Creates a new [FileDescriptor] with [name] and [contents].
+FileDescriptor binaryFile(Pattern name, List<int> contents) =>
+    new FileDescriptor.bytes(name, contents);
+
+/// Creates a new [DirectoryDescriptor] with [name] and [contents].
+DirectoryDescriptor dir(Pattern name, [List<Descriptor> contents]) =>
+    new DirectoryDescriptor(name, contents);
+
+/// Creates a new [FutureDescriptor] wrapping [future].
+FutureDescriptor async(Future<Descriptor> future) =>
+    new FutureDescriptor(future);
+
+/// Creates a new [GitRepoDescriptor] with [name] and [contents].
+GitRepoDescriptor git(Pattern name, [List<Descriptor> contents]) =>
+    new GitRepoDescriptor(name, contents);
+
+/// Creates a new [TarFileDescriptor] with [name] and [contents].
+TarFileDescriptor tar(Pattern name, [List<Descriptor> contents]) =>
+    new TarFileDescriptor(name, contents);
+
+/// Creates a new [NothingDescriptor] with [name].
+NothingDescriptor nothing(String name) => new NothingDescriptor(name);
+
 /// The current [HttpServer] created using [serve].
 var _server;
 
 /// The cached value for [_portCompleter].
 Completer<int> _portCompleterCache;
 
 /// The completer for [port].
 Completer<int> get _portCompleter {
   if (_portCompleterCache != null) return _portCompleterCache;
   _portCompleterCache = new Completer<int>();
-  currentSchedule.onComplete.schedule(() {
+  _scheduleCleanup((_) {
     _portCompleterCache = null;
-  }, 'clearing the port completer');
+  });
   return _portCompleterCache;
 }
 
 /// A future that will complete to the port used for the current server.
 Future<int> get port => _portCompleter.future;
 
 /// Creates an HTTP server to serve [contents] as static files. This server will
 /// exist only for the duration of the pub run.
 ///
 /// Subsequent calls to [serve] will replace the previous server.
-void serve([List<d.Descriptor> contents]) {
-  var baseDir = d.dir("serve-dir", contents);
+void serve([List<Descriptor> contents]) {
+  var baseDir = dir("serve-dir", contents);
 
-  schedule(() {
+  _schedule((_) {
     return _closeServer().then((_) {
       return SafeHttpServer.bind("127.0.0.1", 0).then((server) {
         _server = server;
         server.listen((request) {
           var response = request.response;
+          var path = request.uri.path.replaceFirst("/", "").split("/");
+          response.persistentConnection = false;
+          var stream;
           try {
-            var path = request.uri.path.replaceFirst("/", "");
-            response.persistentConnection = false;
-            var stream = baseDir.load(path);
-
-            new ByteStream(stream).toBytes().then((data) {
-              response.statusCode = 200;
-              response.contentLength = data.length;
-              response.writeBytes(data);
-              response.close();
-            }).catchError((e) {
-              response.statusCode = 404;
-              response.contentLength = 0;
-              response.close();
-            });
+            stream = baseDir.load(path);
           } catch (e) {
-            currentSchedule.signalError(e);
-            response.statusCode = 500;
+            response.statusCode = 404;
+            response.contentLength = 0;
             response.close();
             return;
           }
+
+          stream.toBytes().then((data) {
+            response.statusCode = 200;
+            response.contentLength = data.length;
+            response.writeBytes(data);
+            response.close();
+          }).catchError((e) {
+            print("Exception while handling ${request.uri}: $e");
+            response.statusCode = 500;
+            response.reasonPhrase = e.message;
+            response.close();
+          });
         });
         _portCompleter.complete(_server.port);
-        currentSchedule.onComplete.schedule(_closeServer);
+        _scheduleCleanup((_) => _closeServer());
         return null;
       });
     });
-  }, 'starting a server serving:\n${baseDir.describe()}');
+  });
 }
 
 /// Closes [_server]. Returns a [Future] that will complete after the [_server]
 /// is closed.
 Future _closeServer() {
   if (_server == null) return new Future.immediate(null);
   _server.close();
   _server = null;
   _portCompleterCache = null;
   // TODO(nweiz): Remove this once issue 4155 is fixed. Pumping the event loop
   // *seems* to be enough to ensure that the server is actually closed, but I'm
   // putting this at 10ms to be safe.
   return sleep(10);
 }
 
-/// The [d.DirectoryDescriptor] describing the server layout of packages that
-/// are being served via [servePackages]. This is `null` if [servePackages] has
-/// not yet been called for this test.
-d.DirectoryDescriptor _servedPackageDir;
+/// The [DirectoryDescriptor] describing the server layout of packages that are
+/// being served via [servePackages]. This is `null` if [servePackages] has not
+/// yet been called for this test.
+DirectoryDescriptor _servedPackageDir;
 
 /// A map from package names to version numbers to YAML-serialized pubspecs for
 /// those packages. This represents the packages currently being served by
 /// [servePackages], and is `null` if [servePackages] has not yet been called
 /// for this test.
 Map<String, Map<String, String>> _servedPackages;
 
 /// Creates an HTTP server that replicates the structure of pub.dartlang.org.
 /// [pubspecs] is a list of unserialized pubspecs representing the packages to
 /// serve.
 ///
 /// Subsequent calls to [servePackages] will add to the set of packages that
 /// are being served. Previous packages will continue to be served.
 void servePackages(List<Map> pubspecs) {
   if (_servedPackages == null || _servedPackageDir == null) {
     _servedPackages = <String, Map<String, String>>{};
-    _servedPackageDir = d.dir('packages', []);
+    _servedPackageDir = dir('packages', []);
     serve([_servedPackageDir]);
 
-    currentSchedule.onComplete.schedule(() {
+    _scheduleCleanup((_) {
       _servedPackages = null;
       _servedPackageDir = null;
-    }, 'cleaning up served packages');
+    });
   }
 
-  schedule(() {
-    return awaitObject(pubspecs).then((resolvedPubspecs) {
+  _schedule((_) {
+    return _awaitObject(pubspecs).then((resolvedPubspecs) {
       for (var spec in resolvedPubspecs) {
         var name = spec['name'];
         var version = spec['version'];
         var versions = _servedPackages.putIfAbsent(
             name, () => <String, String>{});
         versions[version] = yaml(spec);
       }
 
       _servedPackageDir.contents.clear();
       for (var name in _servedPackages.keys) {
         var versions = _servedPackages[name].keys.toList();
         _servedPackageDir.contents.addAll([
-          d.file('$name.json', json.stringify({'versions': versions})),
-          d.dir(name, [
-            d.dir('versions', flatten(versions.map((version) {
+          file('$name.json',
+              json.stringify({'versions': versions})),
+          dir(name, [
+            dir('versions', flatten(versions.map((version) {
               return [
-                d.file('$version.yaml', _servedPackages[name][version]),
-                d.tar('$version.tar.gz', [
-                  d.file('pubspec.yaml', _servedPackages[name][version]),
-                  d.libDir(name, '$name $version')
+                file('$version.yaml', _servedPackages[name][version]),
+                tar('$version.tar.gz', [
+                  file('pubspec.yaml', _servedPackages[name][version]),
+                  libDir(name, '$name $version')
                 ])
               ];
             })))
           ])
         ]);
       }
     });
-  }, 'initializing the package server');
+  });
 }
 
 /// Converts [value] into a YAML string.
 String yaml(value) => json.stringify(value);
 
+/// Describes a package that passes all validation.
+Descriptor get normalPackage => dir(appPath, [
+  libPubspec("test_pkg", "1.0.0"),
+  file("LICENSE", "Eh, do what you want."),
+  dir("lib", [
+    file("test_pkg.dart", "int i = 1;")
+  ])
+]);
+
+/// Describes a file named `pubspec.yaml` with the given YAML-serialized
+/// [contents], which should be a serializable object.
+///
+/// [contents] may contain [Future]s that resolve to serializable objects,
+/// which may in turn contain [Future]s recursively.
+Descriptor pubspec(Map contents) {
+  return async(_awaitObject(contents).then((resolvedContents) =>
+      file("pubspec.yaml", yaml(resolvedContents))));
+}
+
+/// Describes a file named `pubspec.yaml` for an application package with the
+/// given [dependencies].
+Descriptor appPubspec(List dependencies) {
+  return pubspec({
+    "name": "myapp",
+    "dependencies": _dependencyListToMap(dependencies)
+  });
+}
+
+/// Describes a file named `pubspec.yaml` for a library package with the given
+/// [name], [version], and [deps]. If "sdk" is given, then it adds an SDK
+/// constraint on that version.
+Descriptor libPubspec(String name, String version, {List deps, String sdk}) {
+  var map = package(name, version, deps);
+
+  if (sdk != null) {
+    map["environment"] = {
+      "sdk": sdk
+    };
+  }
+
+  return pubspec(map);
+}
+
+/// Describes a directory named `lib` containing a single dart file named
+/// `<name>.dart` that contains a line of Dart code.
+Descriptor libDir(String name, [String code]) {
+  // Default to printing the name if no other code was given.
+  if (code == null) {
+    code = name;
+  }
+
+  return dir("lib", [
+    file("$name.dart", 'main() => "$code";')
+  ]);
+}
+
+/// Describes a map representing a library package with the given [name],
+/// [version], and [dependencies].
+Map package(String name, String version, [List dependencies]) {
+  var package = {
+    "name": name,
+    "version": version,
+    "author": "Nathan Weizenbaum <nweiz@google.com>",
+    "homepage": "http://pub.dartlang.org",
+    "description": "A package, I guess."
+  };
+  if (dependencies != null) {
+    package["dependencies"] = _dependencyListToMap(dependencies);
+  }
+  return package;
+}
+
+/// Describes a map representing a dependency on a package in the package
+/// repository.
+Map dependency(String name, [String versionConstraint]) {
+  var url = port.then((p) => "http://localhost:$p");
+  var dependency = {"hosted": {"name": name, "url": url}};
+  if (versionConstraint != null) dependency["version"] = versionConstraint;
+  return dependency;
+}
+
+/// Describes a directory for a package installed from the mock package server.
+/// This directory is of the form found in the global package cache.
+DirectoryDescriptor packageCacheDir(String name, String version) {
+  return dir("$name-$version", [
+    libDir(name, '$name $version')
+  ]);
+}
+
+/// Describes a directory for a Git package. This directory is of the form
+/// found in the revision cache of the global package cache.
+DirectoryDescriptor gitPackageRevisionCacheDir(String name, [int modifier]) {
+  var value = name;
+  if (modifier != null) value = "$name $modifier";
+  return dir(new RegExp("$name${r'-[a-f0-9]+'}"), [
+    libDir(name, value)
+  ]);
+}
+
+/// Describes a directory for a Git package. This directory is of the form
+/// found in the repo cache of the global package cache.
+DirectoryDescriptor gitPackageRepoCacheDir(String name) {
+  return dir(new RegExp("$name${r'-[a-f0-9]+'}"), [
+    dir('hooks'),
+    dir('info'),
+    dir('objects'),
+    dir('refs')
+  ]);
+}
+
+/// Describes the `packages/` directory containing all the given [packages],
+/// which should be name/version pairs. The packages will be validated against
+/// the format produced by the mock package server.
+///
+/// A package with a null version should not be installed.
+DirectoryDescriptor packagesDir(Map<String, String> packages) {
+  var contents = <Descriptor>[];
+  packages.forEach((name, version) {
+    if (version == null) {
+      contents.add(nothing(name));
+    } else {
+      contents.add(dir(name, [
+        file("$name.dart", 'main() => "$name $version";')
+      ]));
+    }
+  });
+  return dir(packagesPath, contents);
+}
+
+/// Describes the global package cache directory containing all the given
+/// [packages], which should be name/version pairs. The packages will be
+/// validated against the format produced by the mock package server.
+///
+/// A package's value may also be a list of versions, in which case all
+/// versions are expected to be installed.
+DirectoryDescriptor cacheDir(Map packages) {
+  var contents = <Descriptor>[];
+  packages.forEach((name, versions) {
+    if (versions is! List) versions = [versions];
+    for (var version in versions) {
+      contents.add(packageCacheDir(name, version));
+    }
+  });
+  return dir(cachePath, [
+    dir('hosted', [
+      async(port.then((p) => dir('localhost%58$p', contents)))
+    ])
+  ]);
+}
+
+/// Describes the file in the system cache that contains the client's OAuth2
+/// credentials. The URL "/token" on [server] will be used as the token
+/// endpoint for refreshing the access token.
+Descriptor credentialsFile(
+    ScheduledServer server,
+    String accessToken,
+    {String refreshToken,
+     DateTime expiration}) {
+  return async(server.url.then((url) {
+    return dir(cachePath, [
+      file('credentials.json', new oauth2.Credentials(
+          accessToken,
+          refreshToken,
+          url.resolve('/token'),
+          ['https://www.googleapis.com/auth/userinfo.email'],
+          expiration).toJson())
+    ]);
+  }));
+}
+
+/// Describes the application directory, containing only a pubspec specifying
+/// the given [dependencies].
+DirectoryDescriptor appDir(List dependencies) =>
+  dir(appPath, [appPubspec(dependencies)]);
+
+/// Converts a list of dependencies as passed to [package] into a hash as used
+/// in a pubspec.
+Future<Map> _dependencyListToMap(List<Map> dependencies) {
+  return _awaitObject(dependencies).then((resolvedDependencies) {
+    var result = <String, Map>{};
+    for (var dependency in resolvedDependencies) {
+      var keys = dependency.keys.where((key) => key != "version");
+      var sourceName = only(keys);
+      var source;
+      switch (sourceName) {
+      case "git":
+        source = new GitSource();
+        break;
+      case "hosted":
+        source = new HostedSource();
+        break;
+      case "path":
+        source = new PathSource();
+        break;
+      default:
+        throw 'Unknown source "$sourceName"';
+      }
+
+      result[_packageName(sourceName, dependency[sourceName])] = dependency;
+    }
+    return result;
+  });
+}
+
+/// Return the name for the package described by [description] and from
+/// [sourceName].
+String _packageName(String sourceName, description) {
+  switch (sourceName) {
+  case "git":
+    var url = description is String ? description : description['url'];
+    // TODO(rnystrom): Using path.basename on a URL is hacky. If we add URL
+    // support to pkg/pathos, should use an explicit builder for that.
+    return path.basename(url.replaceFirst(new RegExp(r"(\.git)?/?$"), ""));
+  case "hosted":
+    if (description is String) return description;
+    return description['name'];
+  case "path":
+    return path.basename(description);
+  case "sdk":
+    return description;
+  default:
+    return description;
+  }
+}
+
 /// The full path to the created sandbox directory for an integration test.
 String get sandboxDir => _sandboxDir;
 String _sandboxDir;
 
 /// The path of the package cache directory used for tests. Relative to the
 /// sandbox directory.
 final String cachePath = "cache";
 
 /// The path of the mock SDK directory used for tests. Relative to the sandbox
 /// directory.
 final String sdkPath = "sdk";
 
 /// The path of the mock app directory used for tests. Relative to the sandbox
 /// directory.
 final String appPath = "myapp";
 
 /// The path of the packages directory in the mock app used for tests. Relative
 /// to the sandbox directory.
 final String packagesPath = "$appPath/packages";
 
+/// The type for callbacks that will be fired during [schedulePub]. Takes the
+/// sandbox directory as a parameter.
+typedef Future _ScheduledEvent(String parentDir);
+
+/// The list of events that are scheduled to run as part of the test case.
+Queue<_ScheduledEvent> _scheduled;
+
+/// The list of events that are scheduled to run after the test case, even if
+/// it failed.
+Queue<_ScheduledEvent> _scheduledCleanup;
+
+/// The list of events that are scheduled to run after the test case only if it
+/// failed.
+Queue<_ScheduledEvent> _scheduledOnException;
+
 /// Set to true when the current batch of scheduled events should be aborted.
 bool _abortScheduled = false;
 
 /// The time (in milliseconds) to wait for the entire scheduled test to
 /// complete.
 final _TIMEOUT = 30000;
 
 /// Defines an integration test. The [body] should schedule a series of
 /// operations which will be run asynchronously.
 void integration(String description, void body()) =>
   _integration(description, body, test);
 
 /// Like [integration], but causes only this test to run.
 void solo_integration(String description, void body()) =>
   _integration(description, body, solo_test);
 
 void _integration(String description, void body(), [Function testFn]) {
   testFn(description, () {
     // Ensure the SDK version is always available.
-    d.dir(sdkPath, [
-      d.file('version', '0.1.2.3')
-    ]).create();
+    dir(sdkPath, [
+      file('version', '0.1.2.3')
+    ]).scheduleCreate();
 
     _sandboxDir = createTempDir();
-    d.defaultRoot = sandboxDir;
-    currentSchedule.onComplete.schedule(() => deleteDir(_sandboxDir),
-        'deleting the sandbox directory');
 
     // Schedule the test.
     body();
+
+    // Run all of the scheduled tasks. If an error occurs, it will propagate
+    // through the futures back up to here where we can hand it off to unittest.
+    var asyncDone = expectAsync0(() {});
+    return timeout(_runScheduled(_scheduled),
+          _TIMEOUT, 'waiting for a test to complete').catchError((e) {
+      return _runScheduled(_scheduledOnException).then((_) {
+        // Rethrow the original error so it keeps propagating.
+        throw e;
+      });
+    }).whenComplete(() {
+      // Clean up after ourselves. Do this first before reporting back to
+      // unittest because it will advance to the next test immediately.
+      return _runScheduled(_scheduledCleanup).then((_) {
+        _scheduled = null;
+        _scheduledCleanup = null;
+        _scheduledOnException = null;
+        if (_sandboxDir != null) {
+          var dir = _sandboxDir;
+          _sandboxDir = null;
+          return deleteDir(dir);
+        }
+      });
+    }).then((_) {
+      // If we got here, the test completed successfully so tell unittest so.
+      asyncDone();
+    }).catchError((e) {
+      // If we got here, an error occurred. We will register it with unittest
+      // directly so that the error message isn't wrapped in any matcher stuff.
+      // We do this call last because it will cause unittest to *synchronously*
+      // advance to the next test and run it.
+      registerException(e.error, e.stackTrace);
+    });
   });
 }
 
 /// Get the path to the root "util/test/pub" directory containing the pub
 /// tests.
 String get testDirectory {
   var dir = new Options().script;
   while (path.basename(dir) != 'pub') dir = path.dirname(dir);
 
   return path.absolute(dir);
 }
 
 /// Schedules renaming (moving) the directory at [from] to [to], both of which
 /// are assumed to be relative to [sandboxDir].
 void scheduleRename(String from, String to) {
-  schedule(
-      () => renameDir(
-          path.join(sandboxDir, from),
-          path.join(sandboxDir, to)),
-      'renaming $from to $to');
+  _schedule((sandboxDir) {
+    return renameDir(path.join(sandboxDir, from), path.join(sandboxDir, to));
+  });
 }
 
+
 /// Schedules creating a symlink at path [symlink] that points to [target],
 /// both of which are assumed to be relative to [sandboxDir].
 void scheduleSymlink(String target, String symlink) {
-  schedule(
-      () => createSymlink(
-          path.join(sandboxDir, target),
-          path.join(sandboxDir, symlink)),
-      'symlinking $target to $symlink');
+  _schedule((sandboxDir) {
+    return createSymlink(path.join(sandboxDir, target),
+        path.join(sandboxDir, symlink));
+  });
 }
 
 /// Schedules a call to the Pub command-line utility. Runs Pub with [args] and
 /// validates that its results match [output], [error], and [exitCode].
 void schedulePub({List args, Pattern output, Pattern error,
     Future<Uri> tokenEndpoint, int exitCode: 0}) {
-  var pub = startPub(args: args, tokenEndpoint: tokenEndpoint);
-  pub.shouldExit(exitCode);
+  _schedule((sandboxDir) {
+    return _doPub(runProcess, sandboxDir, args, tokenEndpoint).then((result) {
+      var failures = [];
 
-  expect(Future.wait([
-    pub.remainingStdout(),
-    pub.remainingStderr()
-  ]).then((results) {
-    var failures = [];
-    _validateOutput(failures, 'stdout', output, results[0].split('\n'));
-    _validateOutput(failures, 'stderr', error, results[1].split('\n'));
-    if (!failures.isEmpty) throw new TestFailure(failures.join('\n'));
-  }), completes);
+      _validateOutput(failures, 'stdout', output, result.stdout);
+      _validateOutput(failures, 'stderr', error, result.stderr);
+
+      if (result.exitCode != exitCode) {
+        failures.add(
+            'Pub returned exit code ${result.exitCode}, expected $exitCode.');
+      }
+
+      if (failures.length > 0) {
+        if (error == null) {
+          // If we aren't validating the error, still show it on failure.
+          failures.add('Pub stderr:');
+          failures.addAll(result.stderr.map((line) => '| $line'));
+        }
+
+        throw new TestFailure(failures.join('\n'));
+      }
+
+      return null;
+    });
+  });
+}
+
+/// 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}) {
+  var process = _scheduleValue((sandboxDir) =>
+      _doPub(startProcess, sandboxDir, args, tokenEndpoint));
+  return new ScheduledProcess("pub", process);
 }
 
 /// Like [startPub], but runs `pub lish` in particular with [server] used both
 /// as the OAuth2 server (with "/token" as the token endpoint) and as the
 /// package server.
 ///
 /// Any futures in [args] will be resolved before the process is started.
-ScheduledProcess startPublish(ScheduledServer server, {List args}) {
+ScheduledProcess startPubLish(ScheduledServer server, {List args}) {
   var tokenEndpoint = server.url.then((url) =>
       url.resolve('/token').toString());
   if (args == null) args = [];
   args = flatten(['lish', '--server', tokenEndpoint, args]);
   return startPub(args: args, tokenEndpoint: tokenEndpoint);
 }
 
 /// Handles the beginning confirmation process for uploading a packages.
 /// Ensures that the right output is shown and then enters "y" to confirm the
 /// upload.
 void confirmPublish(ScheduledProcess pub) {
   // TODO(rnystrom): This is overly specific and inflexible regarding different
   // test packages. Should validate this a little more loosely.
-  expect(pub.nextLine(), completion(equals('Publishing "test_pkg" 1.0.0:')));
-  expect(pub.nextLine(), completion(equals("|-- LICENSE")));
-  expect(pub.nextLine(), completion(equals("|-- lib")));
-  expect(pub.nextLine(), completion(equals("|   '-- test_pkg.dart")));
-  expect(pub.nextLine(), completion(equals("'-- pubspec.yaml")));
-  expect(pub.nextLine(), completion(equals("")));
+  expectLater(pub.nextLine(), equals('Publishing "test_pkg" 1.0.0:'));
+  expectLater(pub.nextLine(), equals("|-- LICENSE"));
+  expectLater(pub.nextLine(), equals("|-- lib"));
+  expectLater(pub.nextLine(), equals("|   '-- test_pkg.dart"));
+  expectLater(pub.nextLine(), equals("'-- pubspec.yaml"));
+  expectLater(pub.nextLine(), equals(""));
 
   pub.writeLine("y");
 }
 
-/// 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}) {
+/// Calls [fn] with appropriately modified arguments to run a pub process. [fn]
+/// should have the same signature as [startProcess], except that the returned
+/// [Future] may have a type other than [Process].
+Future _doPub(Function fn, sandboxDir, List args, Future<Uri> tokenEndpoint) {
   String pathInSandbox(String relPath) {
     return path.join(path.absolute(sandboxDir), relPath);
   }
 
-  ensureDir(pathInSandbox(appPath));
+  return defer(() {
+    ensureDir(pathInSandbox(appPath));
+    return Future.wait([
+      _awaitObject(args),
+      tokenEndpoint == null ? new Future.immediate(null) : tokenEndpoint
+    ]);
+  }).then((results) {
+    var args = results[0];
+    var tokenEndpoint = results[1];
+    // Find a Dart executable we can use to spawn. Use the same one that was
+    // used to run this script itself.
+    var dartBin = new Options().executable;
 
-  // Find a Dart executable we can use to spawn. Use the same one that was
-  // used to run this script itself.
-  var dartBin = new Options().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 = new File(dartBin).fullPathSync();
+    }
 
-  // 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 = new File(dartBin).fullPathSync();
-  }
+    // Find the main pub entrypoint.
+    var pubPath = fs.joinPaths(testDirectory, '../../pub/pub.dart');
 
-  // Find the main pub entrypoint.
-  var pubPath = fs.joinPaths(testDirectory, '../../pub/pub.dart');
+    var dartArgs = ['--checked', pubPath, '--trace'];
+    dartArgs.addAll(args);
 
-  var dartArgs = ['--checked', pubPath, '--trace'];
-  dartArgs.addAll(args);
-
-  if (tokenEndpoint == null) tokenEndpoint = new Future.immediate(null);
-  var optionsFuture = tokenEndpoint.then((tokenEndpoint) {
-    var options = new ProcessOptions();
-    options.workingDirectory = pathInSandbox(appPath);
-    options.environment = {
+    var environment = {
       'PUB_CACHE': pathInSandbox(cachePath),
       'DART_SDK': pathInSandbox(sdkPath)
     };
+
     if (tokenEndpoint != null) {
-      options.environment['_PUB_TEST_TOKEN_ENDPOINT'] =
-        tokenEndpoint.toString();
+      environment['_PUB_TEST_TOKEN_ENDPOINT'] = tokenEndpoint.toString();
     }
-    return options;
+
+    return fn(dartBin, dartArgs, workingDir: pathInSandbox(appPath),
+        environment: environment);
   });
-
-  return new ScheduledProcess.start(dartBin, dartArgs, options: optionsFuture,
-      description: args.isEmpty ? 'pub' : 'pub ${args.first}');
 }
 
 /// Skips the current test if Git is not installed. This validates that the
 /// current test is running on a buildbot in which case we expect git to be
 /// installed. If we are not running on the buildbot, we will instead see if
 /// git is installed and skip the test if not. This way, users don't need to
 /// have git installed to run the tests locally (unless they actually care
 /// about the pub git tests).
 void ensureGit() {
-  schedule(() {
+  _schedule((_) {
     return gitlib.isInstalled.then((installed) {
-      if (installed) return;
-      if (Platform.environment.containsKey('BUILDBOT_BUILDERNAME')) return;
-      currentSchedule.abort();
+      if (!installed &&
+          !Platform.environment.containsKey('BUILDBOT_BUILDERNAME')) {
+        _abortScheduled = true;
+      }
+      return null;
     });
-  }, 'ensuring that Git is installed');
+  });
 }
 
 /// Use [client] as the mock HTTP client for this test.
 ///
 /// Note that this will only affect HTTP requests made via http.dart in the
 /// parent process.
 void useMockClient(MockClient client) {
   var oldInnerClient = httpClient.inner;
   httpClient.inner = client;
-  currentSchedule.onComplete.schedule(() {
+  _scheduleCleanup((_) {
     httpClient.inner = oldInnerClient;
-  }, 'de-activating the mock client');
-}
-
-/// Describes a map representing a library package with the given [name],
-/// [version], and [dependencies].
-Map packageMap(String name, String version, [List dependencies]) {
-  var package = {
-    "name": name,
-    "version": version,
-    "author": "Nathan Weizenbaum <nweiz@google.com>",
-    "homepage": "http://pub.dartlang.org",
-    "description": "A package, I guess."
-  };
-  if (dependencies != null) {
-    package["dependencies"] = dependencyListToMap(dependencies);
-  }
-  return package;
-}
-
-/// Describes a map representing a dependency on a package in the package
-/// repository.
-Map dependencyMap(String name, [String versionConstraint]) {
-  var url = port.then((p) => "http://localhost:$p");
-  var dependency = {"hosted": {"name": name, "url": url}};
-  if (versionConstraint != null) dependency["version"] = versionConstraint;
-  return dependency;
-}
-
-/// Converts a list of dependencies as passed to [package] into a hash as used
-/// in a pubspec.
-Future<Map> dependencyListToMap(List<Map> dependencies) {
-  return awaitObject(dependencies).then((resolvedDependencies) {
-    var result = <String, Map>{};
-    for (var dependency in resolvedDependencies) {
-      var keys = dependency.keys.where((key) => key != "version");
-      var sourceName = only(keys);
-      var source;
-      switch (sourceName) {
-      case "git":
-        source = new GitSource();
-        break;
-      case "hosted":
-        source = new HostedSource();
-        break;
-      case "path":
-        source = new PathSource();
-        break;
-      default:
-        throw 'Unknown source "$sourceName"';
-      }
-
-      result[_packageName(sourceName, dependency[sourceName])] = dependency;
-    }
-    return result;
   });
 }
 
-/// Return the name for the package described by [description] and from
-/// [sourceName].
-String _packageName(String sourceName, description) {
-  switch (sourceName) {
-  case "git":
-    var url = description is String ? description : description['url'];
-    // TODO(rnystrom): Using path.basename on a URL is hacky. If we add URL
-    // support to pkg/pathos, should use an explicit builder for that.
-    return path.basename(url.replaceFirst(new RegExp(r"(\.git)?/?$"), ""));
-  case "hosted":
-    if (description is String) return description;
-    return description['name'];
-  case "path":
-    return path.basename(description);
-  case "sdk":
-    return description;
-  default:
-    return description;
+Future _runScheduled(Queue<_ScheduledEvent> scheduled) {
+  if (scheduled == null) return new Future.immediate(null);
+
+  Future runNextEvent(_) {
+    if (_abortScheduled || scheduled.isEmpty) {
+      _abortScheduled = false;
+      return new Future.immediate(null);
+    }
+
+    var future = scheduled.removeFirst()(_sandboxDir);
+    if (future != null) {
+      return future.then(runNextEvent);
+    } else {
+      return runNextEvent(null);
+    }
   }
+
+  return runNextEvent(null);
 }
 
 /// Compares the [actual] output from running pub with [expected]. For [String]
 /// patterns, ignores leading and trailing whitespace differences and tries to
 /// report the offending difference in a nice way. For other [Pattern]s, just
 /// reports whether the output contained the pattern.
 void _validateOutput(List<String> failures, String pipe, Pattern expected,
                      List<String> actual) {
   if (expected == null) return;
 
@@ skipping 59 matching lines @@
 
   // If any lines mismatched, show the expected and actual.
   if (failed) {
     failures.add('Expected $pipe:');
     failures.addAll(expected.map((line) => '| $line'));
     failures.add('Got:');
     failures.addAll(results);
   }
 }
 
+/// Base class for [FileDescriptor] and [DirectoryDescriptor] so that a
+/// directory can contain a heterogeneous collection of files and
+/// subdirectories.
+abstract class Descriptor {
+  /// The name of this file or directory. This must be a [String] if the file
+  /// or directory is going to be created.
+  final Pattern name;
+
+  Descriptor(this.name);
+
+  /// Creates the file or directory within [dir]. Returns a [Future] that is
+  /// completed after the creation is done.
+  Future create(dir);
+
+  /// Validates that this descriptor correctly matches the corresponding file
+  /// system entry within [dir]. Returns a [Future] that completes to `null` if
+  /// the entry is valid, or throws an error if it failed.
+  Future validate(String dir);
+
+  /// Deletes the file or directory within [dir]. Returns a [Future] that is
+  /// completed after the deletion is done.
+  Future delete(String dir);
+
+  /// Loads the file at [path] from within this descriptor. If [path] is empty,
+  /// loads the contents of the descriptor itself.
+  ByteStream load(List<String> path);
+
+  /// Schedules the directory to be created before Pub is run with
+  /// [schedulePub]. The directory will be created relative to the sandbox
+  /// directory.
+  // TODO(nweiz): Use implicit closurization once issue 2984 is fixed.
+  void scheduleCreate() => _schedule((dir) => this.create(dir));
+
+  /// Schedules the file or directory to be deleted recursively.
+  void scheduleDelete() => _schedule((dir) => this.delete(dir));
+
+  /// Schedules the directory to be validated after Pub is run with
+  /// [schedulePub]. The directory will be validated relative to the sandbox
+  /// directory.
+  void scheduleValidate() => _schedule((parentDir) => validate(parentDir));
+
+  /// Asserts that the name of the descriptor is a [String] and returns it.
+  String get _stringName {
+    if (name is String) return name;
+    throw 'Pattern $name must be a string.';
+  }
+
+  /// Validates that at least one file in [dir] matching [name] is valid
+  /// according to [validate]. [validate] should throw or complete to an
+  /// exception if the input path is invalid.
+  Future _validateOneMatch(String dir, Future validate(String entry)) {
+    // Special-case strings to support multi-level names like "myapp/packages".
+    if (name is String) {
+      var entry = path.join(dir, name);
+      return defer(() {
+        if (!entryExists(entry)) {
+          throw new TestFailure('Entry $entry not found.');
+        }
+        return validate(entry);
+      });
+    }
+
+    // TODO(nweiz): remove this when issue 4061 is fixed.
+    var stackTrace;
+    try {
+      throw "";
+    } catch (_, localStackTrace) {
+      stackTrace = localStackTrace;
+    }
+
+    return listDir(dir).then((files) {
+      var matches = files.where((file) => endsWithPattern(file, name)).toList();
+      if (matches.isEmpty) {
+        throw new TestFailure('No files in $dir match pattern $name.');
+      }
+      if (matches.length == 1) return validate(matches[0]);
+
+      var failures = [];
+      var successes = 0;
+      var completer = new Completer();
+      checkComplete() {
+        if (failures.length + successes != matches.length) return;
+        if (successes > 0) {
+          completer.complete();
+          return;
+        }
+
+        var error = new StringBuffer();
+        error.write("No files named $name in $dir were valid:\n");
+        for (var failure in failures) {
+          error.write("  $failure\n");
+        }
+        completer.completeError(
+            new TestFailure(error.toString()), stackTrace);
+      }
+
+      for (var match in matches) {
+        var future = validate(match).then((_) {
+          successes++;
+          checkComplete();
+        }).catchError((e) {
+          failures.add(e);
+          checkComplete();
+        });
+      }
+      return completer.future;
+    });
+  }
+}
+
+/// Describes a file. These are used both for setting up an expected directory
+/// tree before running a test, and for validating that the file system matches
+/// some expectations after running it.
+class FileDescriptor extends Descriptor {
+  /// The contents of the file, in bytes.
+  final List<int> contents;
+
+  String get textContents => new String.fromCharCodes(contents);
+
+  FileDescriptor.bytes(Pattern name, this.contents) : super(name);
+
+  FileDescriptor(Pattern name, String contents) :
+      this.bytes(name, encodeUtf8(contents));
+
+  /// Creates the file within [dir]. Returns a [Future] that is completed after
+  /// the creation is done.
+  Future<String> create(dir) =>
+      defer(() => writeBinaryFile(path.join(dir, _stringName), contents));
+
+  /// Deletes the file within [dir]. Returns a [Future] that is completed after
+  /// the deletion is done.
+  Future delete(dir) =>
+      defer(() => deleteFile(path.join(dir, _stringName)));
+
+  /// Validates that this file correctly matches the actual file at [path].
+  Future validate(String path) {
+    return _validateOneMatch(path, (file) {
+      var text = readTextFile(file);
+      if (text == textContents) return null;
+
+      throw new TestFailure(
+          'File $file should contain:\n\n$textContents\n\n'
+          'but contained:\n\n$text');
+    });
+  }
+
+  /// Loads the contents of the file.
+  ByteStream load(List<String> path) {
+    if (!path.isEmpty) {
+      throw "Can't load ${path.join('/')} from within $name: not a directory.";
+    }
+
+    return new ByteStream.fromBytes(contents);
+  }
+}
+
+/// Describes a directory and its contents. These are used both for setting up
+/// an expected directory tree before running a test, and for validating that
+/// the file system matches some expectations after running it.
+class DirectoryDescriptor extends Descriptor {
+  /// The files and directories contained in this directory.
+  final List<Descriptor> contents;
+
+  DirectoryDescriptor(Pattern name, List<Descriptor> contents)
+    : this.contents = contents == null ? <Descriptor>[] : contents,
+      super(name);
+
+  /// Creates the file within [dir]. Returns a [Future] that is completed after
+  /// the creation is done.
+  Future<String> create(parentDir) {
+    return defer(() {
+      // Create the directory.
+      var dir = ensureDir(path.join(parentDir, _stringName));
+      if (contents == null) return dir;
+
+      // Recursively create all of its children.
+      var childFutures = contents.map((child) => child.create(dir)).toList();
+      // Only complete once all of the children have been created too.
+      return Future.wait(childFutures).then((_) => dir);
+    });
+  }
+
+  /// Deletes the directory within [dir]. Returns a [Future] that is completed
+  /// after the deletion is done.
+  Future delete(dir) {
+    return deleteDir(path.join(dir, _stringName));
+  }
+
+  /// Validates that the directory at [path] contains all of the expected
+  /// contents in this descriptor. Note that this does *not* check that the
+  /// directory doesn't contain other unexpected stuff, just that it *does*
+  /// contain the stuff we do expect.
+  Future validate(String path) {
+    return _validateOneMatch(path, (dir) {
+      // Validate each of the items in this directory.
+      final entryFutures =
+          contents.map((entry) => entry.validate(dir)).toList();
+
+      // If they are all valid, the directory is valid.
+      return Future.wait(entryFutures).then((entries) => null);
+    });
+  }
+
+  /// Loads [path] from within this directory.
+  ByteStream load(List<String> path) {
+    if (path.isEmpty) {
+      throw "Can't load the contents of $name: is a directory.";
+    }
+
+    for (var descriptor in contents) {
+      if (descriptor.name == path[0]) {
+        return descriptor.load(path.sublist(1));
+      }
+    }
+
+    throw "Directory $name doesn't contain ${path.join('/')}.";
+  }
+}
+
+/// Wraps a [Future] that will complete to a [Descriptor] and makes it behave
+/// like a concrete [Descriptor]. This is necessary when the contents of the
+/// descriptor depends on information that's not available until part of the
+/// test run is completed.
+class FutureDescriptor extends Descriptor {
+  Future<Descriptor> _future;
+
+  FutureDescriptor(this._future) : super('<unknown>');
+
+  Future create(dir) => _future.then((desc) => desc.create(dir));
+
+  Future validate(dir) => _future.then((desc) => desc.validate(dir));
+
+  Future delete(dir) => _future.then((desc) => desc.delete(dir));
+
+  ByteStream load(List<String> path) {
+    var controller = new StreamController<List<int>>();
+    _future.then((desc) => store(desc.load(path), controller));
+    return new ByteStream(controller.stream);
+  }
+}
+
+/// Describes a Git repository and its contents.
+class GitRepoDescriptor extends DirectoryDescriptor {
+  GitRepoDescriptor(Pattern name, List<Descriptor> contents)
+  : super(name, contents);
+
+  /// Creates the Git repository and commits the contents.
+  Future create(parentDir) {
+    return _runGitCommands(parentDir, [
+      ['init'],
+      ['add', '.'],
+      ['commit', '-m', 'initial commit']
+    ]);
+  }
+
+  /// Commits any changes to the Git repository.
+  Future commit(parentDir) {
+    return _runGitCommands(parentDir, [
+      ['add', '.'],
+      ['commit', '-m', 'update']
+    ]);
+  }
+
+  /// Schedules changes to be committed to the Git repository.
+  void scheduleCommit() => _schedule((dir) => this.commit(dir));
+
+  /// Return a Future that completes to the commit in the git repository
+  /// referred to by [ref] at the current point in the scheduled test run.
+  Future<String> revParse(String ref) {
+    return _scheduleValue((parentDir) {
+      return super.create(parentDir).then((rootDir) {
+        return _runGit(['rev-parse', ref], rootDir);
+      }).then((output) => output[0]);
+    });
+  }
+
+  /// Schedule a Git command to run in this repository.
+  void scheduleGit(List<String> args) {
+    _schedule((parentDir) => _runGit(args, path.join(parentDir, name)));
+  }
+
+  Future _runGitCommands(parentDir, List<List<String>> commands) {
+    var workingDir;
+
+    Future runGitStep(_) {
+      if (commands.isEmpty) return new Future.immediate(workingDir);
+      var command = commands.removeAt(0);
+      return _runGit(command, workingDir).then(runGitStep);
+    }
+
+    return super.create(parentDir).then((rootDir) {
+      workingDir = rootDir;
+      return runGitStep(null);
+    });
+  }
+
+  Future<List<String>> _runGit(List<String> args, String workingDir) {
+    // Explicitly specify the committer information. Git needs this to commit
+    // and we don't want to rely on the buildbots having this already set up.
+    var environment = {
+      'GIT_AUTHOR_NAME': 'Pub Test',
+      'GIT_AUTHOR_EMAIL': 'pub@dartlang.org',
+      'GIT_COMMITTER_NAME': 'Pub Test',
+      'GIT_COMMITTER_EMAIL': 'pub@dartlang.org'
+    };
+
+    return gitlib.run(args, workingDir: workingDir, environment: environment);
+  }
+}
+
+/// Describes a gzipped tar file and its contents.
+class TarFileDescriptor extends Descriptor {
+  final List<Descriptor> contents;
+
+  TarFileDescriptor(Pattern name, this.contents)
+  : super(name);
+
+  /// Creates the files and directories within this tar file, then archives
+  /// them, compresses them, and saves the result to [parentDir].
+  Future<String> create(parentDir) {
+    return withTempDir((tempDir) {
+      return Future.wait(contents.map((child) => child.create(tempDir)))
+          .then((createdContents) {
+        return createTarGz(createdContents, baseDir: tempDir).toBytes();
+      }).then((bytes) {
+        var file = path.join(parentDir, _stringName);
+        writeBinaryFile(file, bytes);
+        return file;
+      });
+    });
+  }
+
+  /// Validates that the `.tar.gz` file at [path] contains the expected
+  /// contents.
+  Future validate(String path) {
+    throw "TODO(nweiz): implement this";
+  }
+
+  Future delete(dir) {
+    throw new UnsupportedError('');
+  }
+
+  /// Loads the contents of this tar file.
+  ByteStream load(List<String> path) {
+    if (!path.isEmpty) {
+      throw "Can't load ${path.join('/')} from within $name: not a directory.";
+    }
+
+    var controller = new StreamController<List<int>>();
+    // TODO(nweiz): propagate any errors to the return value. See issue 3657.
+    withTempDir((tempDir) {
+      return create(tempDir).then((tar) {
+        var sourceStream = new File(tar).openRead();
+        return store(sourceStream, controller);
+      });
+    });
+    return new ByteStream(controller.stream);
+  }
+}
+
+/// A descriptor that validates that no file or directory exists with the given
+/// name.
+class NothingDescriptor extends Descriptor {
+  NothingDescriptor(String name) : super(name);
+
+  Future create(dir) => new Future.immediate(null);
+  Future delete(dir) => new Future.immediate(null);
+
+  Future validate(String dir) {
+    return defer(() {
+      if (entryExists(path.join(dir, name))) {
+        throw new TestFailure('Entry $name in $dir should not exist.');
+      }
+    });
+  }
+
+  ByteStream load(List<String> path) {
+    if (path.isEmpty) {
+      throw "Can't load the contents of $name: it doesn't exist.";
+    } else {
+      throw "Can't load ${path.join('/')} from within $name: $name doesn't "
+        "exist.";
+    }
+  }
+}
+
 /// A function that creates a [Validator] subclass.
 typedef Validator ValidatorCreator(Entrypoint entrypoint);
 
 /// Schedules a single [Validator] to run on the [appPath]. Returns a scheduled
 /// Future that contains the errors and warnings produced by that validator.
 Future<Pair<List<String>, List<String>>> schedulePackageValidation(
     ValidatorCreator fn) {
-  return schedule(() {
+  return _scheduleValue((sandboxDir) {
     var cache = new SystemCache.withSources(path.join(sandboxDir, cachePath));
 
     return defer(() {
       var validator = fn(new Entrypoint(path.join(sandboxDir, appPath), cache));
       return validator.validate().then((_) {
         return new Pair(validator.errors, validator.warnings);
       });
     });
-  }, "validating package");
+  });
 }
 
 /// 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) {
     if (item is! Pair) return false;
     return _firstMatcher.matches(item.first, matchState) &&
         _lastMatcher.matches(item.last, matchState);
   }
 
   Description describe(Description description) {
     description.addAll("(", ", ", ")", [_firstMatcher, _lastMatcher]);
   }
 }
+
+/// The time (in milliseconds) to wait for scheduled events that could run
+/// forever.
+const _SCHEDULE_TIMEOUT = 10000;
+
+/// A class representing a [Process] that is scheduled to run in the course of
+/// the test. This class allows actions on the process to be scheduled
+/// synchronously. All operations on this class are scheduled.
+///
+/// Before running the test, either [shouldExit] or [kill] must be called on
+/// this to ensure that the process terminates when expected.
+///
+/// If the test fails, this will automatically print out any remaining stdout
+/// and stderr from the process to aid debugging.
+class ScheduledProcess {
+  /// The name of the process. Used for error reporting.
+  final String name;
+
+  /// The process future that's scheduled to run.
+  Future<PubProcess> _processFuture;
+
+  /// The process that's scheduled to run. It may be null.
+  PubProcess _process;
+
+  /// The exit code of the scheduled program. It may be null.
+  int _exitCode;
+
+  /// A future that will complete to a list of all the lines emitted on the
+  /// process's standard output stream. This is independent of what data is read
+  /// from [_stdout].
+  Future<List<String>> _stdoutLines;
+
+  /// A [Stream] of stdout lines emitted by the process that's scheduled to run.
+  /// It may be null.
+  Stream<String> _stdout;
+
+  /// A [Future] that will resolve to [_stdout] once it's available.
+  Future get _stdoutFuture => _processFuture.then((_) => _stdout);
+
+  /// A [StreamSubscription] that controls [_stdout].
+  StreamSubscription _stdoutSubscription;
+
+  /// A future that will complete to a list of all the lines emitted on the
+  /// process's standard error stream. This is independent of what data is read
+  /// from [_stderr].
+  Future<List<String>> _stderrLines;
+
+  /// A [Stream] of stderr lines emitted by the process that's scheduled to run.
+  /// It may be null.
+  Stream<String> _stderr;
+
+  /// A [Future] that will resolve to [_stderr] once it's available.
+  Future get _stderrFuture => _processFuture.then((_) => _stderr);
+
+  /// A [StreamSubscription] that controls [_stderr].
+  StreamSubscription _stderrSubscription;
+
+  /// The exit code of the process that's scheduled to run. This will naturally
+  /// only complete once the process has terminated.
+  Future<int> get _exitCodeFuture => _exitCodeCompleter.future;
+
+  /// The completer for [_exitCode].
+  final Completer<int> _exitCodeCompleter = new Completer();
+
+  /// 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<PubProcess> process)
+    : _processFuture = process {
+    var pairFuture = process.then((p) {
+      _process = p;
+
+      byteStreamToLines(stream) {
+        return streamToLines(new ByteStream(stream.handleError((e) {
+          registerException(e.error, e.stackTrace);
+        })).toStringStream());
+      }
+
+      var stdoutTee = tee(byteStreamToLines(p.stdout));
+      var stdoutPair = streamWithSubscription(stdoutTee.last);
+      _stdout = stdoutPair.first;
+      _stdoutSubscription = stdoutPair.last;
+
+      var stderrTee = tee(byteStreamToLines(p.stderr));
+      var stderrPair = streamWithSubscription(stderrTee.last);
+      _stderr = stderrPair.first;
+      _stderrSubscription = stderrPair.last;
+
+      return new Pair(stdoutTee.first, stderrTee.first);
+    });
+
+    _stdoutLines = pairFuture.then((pair) => pair.first.toList());
+    _stderrLines = pairFuture.then((pair) => pair.last.toList());
+
+    _schedule((_) {
+      if (!_endScheduled) {
+        throw new StateError("Scheduled process $name must have shouldExit() "
+            "or kill() called before the test is run.");
+      }
+
+      process.then((p) => p.exitCode).then((exitCode) {
+        if (_endExpected) {
+          _exitCode = exitCode;
+          _exitCodeCompleter.complete(exitCode);
+          return;
+        }
+
+        // Sleep for half a second in case _endExpected is set in the next
+        // scheduled event.
+        return sleep(500).then((_) {
+          if (_endExpected) {
+            _exitCodeCompleter.complete(exitCode);
+            return;
+          }
+
+          return _printStreams();
+        }).then((_) {
+          registerException(new TestFailure("Process $name ended "
+              "earlier than scheduled with exit code $exitCode"));
+        });
+      }).catchError((e) => registerException(e.error, e.stackTrace));
+    });
+
+    _scheduleOnException((_) {
+      if (_process == null) return;
+
+      if (_exitCode == null) {
+        print("\nKilling process $name prematurely.");
+        _endExpected = true;
+        _process.kill();
+      }
+
+      return _printStreams();
+    });
+
+    _scheduleCleanup((_) {
+      if (_process == null) return;
+      // Ensure that the process is dead and we aren't waiting on any IO.
+      _process.kill();
+      _stdoutSubscription.cancel();
+      _stderrSubscription.cancel();
+    });
+  }
+
+  /// Reads the next line of stdout from the process.
+  Future<String> nextLine() {
+    return _scheduleValue((_) {
+      return timeout(_stdoutFuture.then((stream) => streamFirst(stream)),
+          _SCHEDULE_TIMEOUT,
+          "waiting for the next stdout line from process $name");
+    });
+  }
+
+  /// Reads the next line of stderr from the process.
+  Future<String> nextErrLine() {
+    return _scheduleValue((_) {
+      return timeout(_stderrFuture.then((stream) => streamFirst(stream)),
+          _SCHEDULE_TIMEOUT,
+          "waiting for the next stderr line from process $name");
+    });
+  }
+
+  /// Reads the remaining stdout from the process. This should only be called
+  /// after kill() or shouldExit().
+  Future<String> remainingStdout() {
+    if (!_endScheduled) {
+      throw new StateError("remainingStdout() should only be called after "
+          "kill() or shouldExit().");
+    }
+
+    return _scheduleValue((_) {
+      return timeout(_stdoutFuture.then((stream) => stream.toList())
+              .then((lines) => lines.join("\n")),
+          _SCHEDULE_TIMEOUT,
+          "waiting for the last stdout line from process $name");
+    });
+  }
+
+  /// Reads the remaining stderr from the process. This should only be called
+  /// after kill() or shouldExit().
+  Future<String> remainingStderr() {
+    if (!_endScheduled) {
+      throw new StateError("remainingStderr() should only be called after "
+          "kill() or shouldExit().");
+    }
+
+    return _scheduleValue((_) {
+      return timeout(_stderrFuture.then((stream) => stream.toList())
+              .then((lines) => lines.join("\n")),
+          _SCHEDULE_TIMEOUT,
+          "waiting for the last stderr line from process $name");
+    });
+  }
+
+  /// Writes [line] to the process as stdin.
+  void writeLine(String line) {
+    _schedule((_) => _processFuture.then(
+        (p) => p.stdin.add(encodeUtf8('$line\n'))));
+  }
+
+  /// Kills the process, and waits until it's dead.
+  void kill() {
+    _endScheduled = true;
+    _schedule((_) {
+      _endExpected = true;
+      _process.kill();
+      timeout(_exitCodeFuture, _SCHEDULE_TIMEOUT,
+          "waiting for process $name to die");
+    });
+  }
+
+  /// Waits for the process to exit, and verifies that the exit code matches
+  /// [expectedExitCode] (if given).
+  void shouldExit([int expectedExitCode]) {
+    _endScheduled = true;
+    _schedule((_) {
+      _endExpected = true;
+      return timeout(_exitCodeFuture, _SCHEDULE_TIMEOUT,
+          "waiting for process $name to exit").then((exitCode) {
+        if (expectedExitCode != null) {
+          expect(exitCode, equals(expectedExitCode));
+        }
+      });
+    });
+  }
+
+  /// Prints the remaining data in the process's stdout and stderr streams.
+  /// Prints nothing if the streams are empty.
+  Future _printStreams() {
+    void printStream(String streamName, List<String> lines) {
+      if (lines.isEmpty) return;
+
+      print('\nProcess $name $streamName:');
+      for (var line in lines) {
+        print('| $line');
+      }
+    }
+
+    return _stdoutLines.then((stdoutLines) {
+      printStream('stdout', stdoutLines);
+      return _stderrLines.then((stderrLines) {
+        printStream('stderr', stderrLines);
+      });
+    });
+  }
+}
+
+/// A class representing an [HttpServer] that's scheduled to run in the course
+/// of the test. This class allows the server's request handling to be
+/// scheduled synchronously. All operations on this class are scheduled.
+class ScheduledServer {
+  /// The wrapped server.
+  final Future<HttpServer> _server;
+
+  /// The queue of handlers to run for upcoming requests.
+  final _handlers = new Queue<Future>();
+
+  /// The requests to be ignored.
+  final _ignored = new Set<Pair<String, String>>();
+
+  ScheduledServer._(this._server);
+
+  /// Creates a new server listening on an automatically-allocated port on
+  /// localhost.
+  factory ScheduledServer() {
+    var scheduledServer;
+    scheduledServer = new ScheduledServer._(_scheduleValue((_) {
+      return SafeHttpServer.bind("127.0.0.1", 0).then((server) {
+        server.listen(scheduledServer._awaitHandle);
+        _scheduleCleanup((_) => server.close());
+        return server;
+      });
+    }));
+    return scheduledServer;
+  }
+
+  /// The port on which the server is listening.
+  Future<int> get port => _server.then((s) => s.port);
+
+  /// The base URL of the server, including its port.
+  Future<Uri> get url =>
+    port.then((p) => Uri.parse("http://localhost:$p"));
+
+  /// Assert that the next request has the given [method] and [path], and pass
+  /// it to [handler] to handle. If [handler] returns a [Future], wait until
+  /// it's completed to continue the schedule.
+  void handle(String method, String path,
+      Future handler(HttpRequest request, HttpResponse response)) {
+    var handlerCompleter = new Completer<Function>();
+    _scheduleValue((_) {
+      var requestCompleteCompleter = new Completer();
+      handlerCompleter.complete((request, response) {
+        expect(request.method, equals(method));
+        expect(request.uri.path, equals(path));
+
+        var future = handler(request, response);
+        if (future == null) future = new Future.immediate(null);
+        chainToCompleter(future, requestCompleteCompleter);
+      });
+      return timeout(requestCompleteCompleter.future,
+          _SCHEDULE_TIMEOUT, "waiting for $method $path");
+    });
+    _handlers.add(handlerCompleter.future);
+  }
+
+  /// Ignore all requests with the given [method] and [path]. If one is
+  /// received, don't respond to it.
+  void ignore(String method, String path) =>
+    _ignored.add(new Pair(method, path));
+
+  /// Raises an error complaining of an unexpected request.
+  void _awaitHandle(HttpRequest request) {
+    HttpResponse response = request.response;
+    if (_ignored.contains(new Pair(request.method, request.uri.path))) return;
+    var future = timeout(defer(() {
+      if (_handlers.isEmpty) {
+        fail('Unexpected ${request.method} request to ${request.uri.path}.');
+      }
+      return _handlers.removeFirst();
+    }).then((handler) {
+      handler(request, response);
+    }), _SCHEDULE_TIMEOUT, "waiting for a handler for ${request.method} "
+        "${request.uri.path}");
+    expect(future, completes);
+  }
+}
+
+/// Takes a simple data structure (composed of [Map]s, [List]s, scalar objects,
+/// and [Future]s) and recursively resolves all the [Future]s contained within.
+/// Completes with the fully resolved structure.
+Future _awaitObject(object) {
+  // Unroll nested futures.
+  if (object is Future) return object.then(_awaitObject);
+  if (object is Collection) {
+    return Future.wait(object.map(_awaitObject).toList());
+  }
+  if (object is! Map) return new Future.immediate(object);
+
+  var pairs = <Future<Pair>>[];
+  object.forEach((key, value) {
+    pairs.add(_awaitObject(value)
+        .then((resolved) => new Pair(key, resolved)));
+  });
+  return Future.wait(pairs).then((resolvedPairs) {
+    var map = {};
+    for (var pair in resolvedPairs) {
+      map[pair.first] = pair.last;
+    }
+    return map;
+  });
+}
+
+/// Schedules a callback to be called as part of the test case.
+void _schedule(_ScheduledEvent event) {
+  if (_scheduled == null) _scheduled = new Queue();
+  _scheduled.addLast(event);
+}
+
+/// Like [_schedule], but pipes the return value of [event] to a returned
+/// [Future].
+Future _scheduleValue(_ScheduledEvent event) {
+  var completer = new Completer();
+  _schedule((parentDir) {
+    chainToCompleter(event(parentDir), completer);
+    return completer.future;
+  });
+  return completer.future;
+}
+
+/// Schedules a callback to be called after the test case has completed, even
+/// if it failed.
+void _scheduleCleanup(_ScheduledEvent event) {
+  if (_scheduledCleanup == null) _scheduledCleanup = new Queue();
+  _scheduledCleanup.addLast(event);
+}
+
+/// Schedules a callback to be called after the test case has completed, but
+/// only if it failed.
+void _scheduleOnException(_ScheduledEvent event) {
+  if (_scheduledOnException == null) _scheduledOnException = new Queue();
+  _scheduledOnException.addLast(event);
+}
+
+/// Like [expect], but for [Future]s that complete as part of the scheduled
+/// test. This is necessary to ensure that the exception thrown by the
+/// expectation failing is handled by the scheduler.
+///
+/// Note that [matcher] matches against the completed value of [actual], so
+/// calling [completion] is unnecessary.
+void expectLater(Future actual, matcher, {String reason,
+    FailureHandler failureHandler, bool verbose: false}) {
+  _schedule((_) {
+    return actual.then((value) {
+      expect(value, matcher, reason: reason, failureHandler: failureHandler,
+          verbose: false);
+    });
+  });
+}