diff --git a/test/cache/repair/handles_failure_test.dart b/test/cache/repair/handles_failure_test.dart
index 0b556394c..fc412ae73 100644
--- a/test/cache/repair/handles_failure_test.dart
+++ b/test/cache/repair/handles_failure_test.dart
@@ -19,7 +19,7 @@ main() {
     // Set up a cache with some packages.
     d.dir(cachePath, [
       d.dir('hosted', [
-        d.async(port.then((p) => d.dir('localhost%58$p', [
+        d.async(globalServer.port.then((p) => d.dir('localhost%58$p', [
           d.dir("foo-1.2.3", [
             d.libPubspec("foo", "1.2.3"),
             d.file("broken.txt")
diff --git a/test/cache/repair/reinstalls_hosted_packages_test.dart b/test/cache/repair/reinstalls_hosted_packages_test.dart
index 871c5df84..07c866823 100644
--- a/test/cache/repair/reinstalls_hosted_packages_test.dart
+++ b/test/cache/repair/reinstalls_hosted_packages_test.dart
@@ -18,7 +18,7 @@ main() {
     // Set up a cache with some broken packages.
     d.dir(cachePath, [
       d.dir('hosted', [
-        d.async(port.then((p) => d.dir('localhost%58$p', [
+        d.async(globalServer.port.then((p) => d.dir('localhost%58$p', [
           d.dir("foo-1.2.3", [
             d.libPubspec("foo", "1.2.3"),
             d.file("broken.txt")
diff --git a/test/descriptor.dart b/test/descriptor.dart
index be7cb71a6..b9a28b36c 100644
--- a/test/descriptor.dart
+++ b/test/descriptor.dart
@@ -153,7 +153,7 @@ Descriptor cacheDir(Map packages, {bool includePubspecs: false}) {
 Descriptor hostedCache(Iterable<Descriptor> contents) {
   return dir(cachePath, [
     dir('hosted', [
-      async(port.then((p) => dir('localhost%58$p', contents)))
+      async(globalServer.port.then((p) => dir('localhost%58$p', contents)))
     ])
   ]);
 }
diff --git a/test/descriptor_server.dart b/test/descriptor_server.dart
new file mode 100644
index 000000000..4270dc6a8
--- /dev/null
+++ b/test/descriptor_server.dart
@@ -0,0 +1,124 @@
+// Copyright (c) 2016, 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.
+
+import 'dart:async';
+import 'dart:io';
+
+import 'package:path/path.dart' as p;
+import 'package:pub/src/utils.dart';
+import 'package:scheduled_test/scheduled_test.dart' hide fail;
+import 'package:shelf/shelf.dart' as shelf;
+import 'package:shelf/shelf_io.dart' as shelf_io;
+
+import 'descriptor.dart' as d;
+
+/// The global [DescriptorServer] that's used by default.
+///
+/// `null` if there's no global server in use. This can be set to replace the
+/// existing global server.
+DescriptorServer get globalServer => _globalServer;
+set globalServer(DescriptorServer value) {
+  if (_globalServer == null) {
+    currentSchedule.onComplete.schedule(() {
+      _globalServer = null;
+    }, 'clearing the global server');
+  } else {
+    _globalServer.close();
+  }
+
+  _globalServer = value;
+}
+DescriptorServer _globalServer;
+
+/// Creates a global [DescriptorServer] to serve [contents] as static files.
+///
+/// This server will exist only for the duration of the pub run. It's accessible
+/// via [server]. Subsequent calls to [serve] replace the previous server.
+void serve([List<d.Descriptor> contents]) {
+  globalServer = new DescriptorServer(contents);
+}
+
+/// Like [serve], but reports an error if a request ever comes in to the server.
+void serveErrors() {
+  globalServer = new DescriptorServer.errors();
+}
+
+class DescriptorServer {
+  /// The server, or `null` before it's available.
+  HttpServer _server;
+
+  /// A future that will complete to the port used for the server.
+  Future<int> get port => _portCompleter.future;
+  final _portCompleter = new Completer<int>();
+
+  /// Gets the list of paths that have been requested from the server.
+  Future<List<String>> get requestedPaths =>
+      schedule(() => _requestedPaths.toList(),
+          "get previous network requests");
+
+  /// The list of paths that have been requested from this server.
+  final _requestedPaths = <String>[];
+
+  /// Creates an HTTP server to serve [contents] as static files.
+  ///
+  /// This server exists only for the duration of the pub run. Subsequent calls
+  /// to [serve] replace the previous server.
+  DescriptorServer([List<d.Descriptor> contents]) {
+    var baseDir = d.dir("serve-dir", contents);
+
+    schedule(() async {
+      _server = await shelf_io.serve((request) async {
+        var path = p.posix.fromUri(request.url.path);
+        _requestedPaths.add(path);
+
+        try {
+          var stream = await validateStream(baseDir.load(path));
+          return new shelf.Response.ok(stream);
+        } catch (_) {
+          return new shelf.Response.notFound('File "$path" not found.');
+        }
+      }, 'localhost', 0);
+
+      _portCompleter.complete(_server.port);
+      _closeOnComplete();
+    }, 'starting a server serving:\n${baseDir.describe()}');
+  }
+
+  /// Creates a server that reports an error if a request is ever received.
+  DescriptorServer.errors() {
+    schedule(() async {
+      _server = await shelf_io.serve((request) {
+        fail("The HTTP server received an unexpected request:\n"
+            "${request.method} ${request.requestedUri}");
+        return new shelf.Response.forbidden(null);
+      }, 'localhost', 0);
+
+      _portCompleter.complete(_server.port);
+      _closeOnComplete();
+    });
+  }
+
+  /// Schedules [requestedPaths] to be emptied.
+  void clearRequestedPaths() {
+    schedule(() {
+      _requestedPaths.clear();
+    }, "clearing requested paths");
+  }
+
+  /// Schedules the closing of this server.
+  void close() {
+    schedule(() async {
+      if (_server == null) return;
+      await _server.close();
+    }, "closing DescriptorServer");
+  }
+
+  /// Schedules this server to close once the schedule is done.
+  void _closeOnComplete() {
+    currentSchedule.onComplete.schedule(() async {
+      if (_server == null) return;
+      await _server.close();
+    }, "closing DescriptorServer");
+  }
+}
diff --git a/test/downgrade/unlock_dependers_test.dart b/test/downgrade/unlock_dependers_test.dart
index 70a628215..6a644c64a 100644
--- a/test/downgrade/unlock_dependers_test.dart
+++ b/test/downgrade/unlock_dependers_test.dart
@@ -22,7 +22,7 @@ main() {
       "bar": "2.0.0"
     }).validate();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("foo", "1.0.0", deps: {"bar": "any"});
       builder.serve("bar", "1.0.0");
     });
diff --git a/test/downgrade/unlock_if_necessary_test.dart b/test/downgrade/unlock_if_necessary_test.dart
index c7eff44e7..a8f4e5f1e 100644
--- a/test/downgrade/unlock_if_necessary_test.dart
+++ b/test/downgrade/unlock_if_necessary_test.dart
@@ -22,7 +22,7 @@ main() {
       "foo_dep": "2.0.0"
     }).validate();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("foo", "1.0.0", deps: {"foo_dep": "<2.0.0"});
       builder.serve("foo_dep", "1.0.0");
     });
diff --git a/test/get/cache_transformed_dependency_test.dart b/test/get/cache_transformed_dependency_test.dart
index b0d64e1ae..a1ab8c440 100644
--- a/test/get/cache_transformed_dependency_test.dart
+++ b/test/get/cache_transformed_dependency_test.dart
@@ -203,7 +203,7 @@ main() {
     d.appDir({"foo": "1.2.3"}).create();
     pubGet(output: contains("Precompiled foo."));
 
-    servePackages((builder) => builder.serve("bar", "6.0.0"));
+    globalPackageServer.add((builder) => builder.serve("bar", "6.0.0"));
     pubUpgrade(output: contains("Precompiled foo."));
   });
 
@@ -227,7 +227,7 @@ main() {
     d.appDir({"foo": "1.2.3"}).create();
     pubGet(output: contains("Precompiled foo."));
 
-    servePackages((builder) => builder.serve("bar", "6.0.0"));
+    globalPackageServer.add((builder) => builder.serve("bar", "6.0.0"));
     pubUpgrade(output: isNot(contains("Precompiled foo.")));
   });
 
diff --git a/test/get/hosted/avoid_network_requests_test.dart b/test/get/hosted/avoid_network_requests_test.dart
index 69afd64e9..54647e9cc 100644
--- a/test/get/hosted/avoid_network_requests_test.dart
+++ b/test/get/hosted/avoid_network_requests_test.dart
@@ -27,7 +27,7 @@ main() {
 
     // Clear the cache. We don't care about anything that was served during
     // the initial get.
-    getRequestedPaths();
+    globalServer.clearRequestedPaths();
 
     // Add "bar" to the dependencies.
     d.appDir({
@@ -45,7 +45,7 @@ main() {
 
     // The get should not have done any network requests since the lock file is
     // up to date.
-    getRequestedPaths().then((paths) {
+    globalServer.requestedPaths.then((paths) {
       expect(paths, unorderedEquals([
         // Bar should be requested because it's new, but not foo.
         "api/packages/bar",
diff --git a/test/get/hosted/cached_pubspec_test.dart b/test/get/hosted/cached_pubspec_test.dart
index 8899d1fba..7d3cf086f 100644
--- a/test/get/hosted/cached_pubspec_test.dart
+++ b/test/get/hosted/cached_pubspec_test.dart
@@ -18,7 +18,7 @@ main() {
 
     // Clear the cache. We don't care about anything that was served during
     // the initial get.
-    getRequestedPaths();
+    globalServer.clearRequestedPaths();
 
     d.cacheDir({"foo": "1.2.3"}).validate();
     d.packagesDir({"foo": "1.2.3"}).validate();
@@ -27,7 +27,7 @@ main() {
     pubGet();
 
     // The get should not have requested the pubspec since it's local already.
-    getRequestedPaths().then((paths) {
+    globalServer.requestedPaths.then((paths) {
       expect(paths, isNot(contains("packages/foo/versions/1.2.3.yaml")));
     });
   });
diff --git a/test/get/hosted/does_no_network_requests_when_possible_test.dart b/test/get/hosted/does_no_network_requests_when_possible_test.dart
index d08d39905..9330121ef 100644
--- a/test/get/hosted/does_no_network_requests_when_possible_test.dart
+++ b/test/get/hosted/does_no_network_requests_when_possible_test.dart
@@ -24,7 +24,7 @@ main() {
 
     // Clear the cache. We don't care about anything that was served during
     // the initial get.
-    getRequestedPaths();
+    globalServer.clearRequestedPaths();
 
     // Run the solver again now that it's cached.
     pubGet();
@@ -34,7 +34,7 @@ main() {
 
     // The get should not have done any network requests since the lock file is
     // up to date.
-    getRequestedPaths().then((paths) {
+    globalServer.requestedPaths.then((paths) {
       expect(paths, isEmpty);
     });
   });
diff --git a/test/get/hosted/stay_locked_if_compatible_test.dart b/test/get/hosted/stay_locked_if_compatible_test.dart
index e2f149fda..75f07b044 100644
--- a/test/get/hosted/stay_locked_if_compatible_test.dart
+++ b/test/get/hosted/stay_locked_if_compatible_test.dart
@@ -16,7 +16,7 @@ main() {
 
     d.packagesDir({"foo": "1.0.0"}).validate();
 
-    servePackages((builder) => builder.serve("foo", "1.0.1"));
+    globalPackageServer.add((builder) => builder.serve("foo", "1.0.1"));
 
     d.appDir({"foo": ">=1.0.0"}).create();
 
diff --git a/test/get/hosted/stay_locked_if_new_is_satisfied_test.dart b/test/get/hosted/stay_locked_if_new_is_satisfied_test.dart
index 5f0da0dcd..7873c354e 100644
--- a/test/get/hosted/stay_locked_if_new_is_satisfied_test.dart
+++ b/test/get/hosted/stay_locked_if_new_is_satisfied_test.dart
@@ -24,7 +24,7 @@ main() {
       "baz": "1.0.0"
     }).validate();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("foo", "2.0.0", deps: {"bar": "<3.0.0"});
       builder.serve("bar", "2.0.0", deps: {"baz": "<3.0.0"});
       builder.serve("baz", "2.0.0");
diff --git a/test/get/hosted/stay_locked_test.dart b/test/get/hosted/stay_locked_test.dart
index e9d2976e3..a1f47ba09 100644
--- a/test/get/hosted/stay_locked_test.dart
+++ b/test/get/hosted/stay_locked_test.dart
@@ -25,7 +25,7 @@ main() {
     schedule(() => deleteEntry(path.join(sandboxDir, packagesPath)));
 
     // Start serving a newer package as well.
-    servePackages((builder) => builder.serve("foo", "1.0.1"));
+    globalPackageServer.add((builder) => builder.serve("foo", "1.0.1"));
 
     // This shouldn't upgrade the foo dependency due to the lockfile.
     pubGet();
diff --git a/test/get/hosted/unlock_if_incompatible_test.dart b/test/get/hosted/unlock_if_incompatible_test.dart
index fb6c7f7a3..08d011c4e 100644
--- a/test/get/hosted/unlock_if_incompatible_test.dart
+++ b/test/get/hosted/unlock_if_incompatible_test.dart
@@ -15,7 +15,7 @@ main() {
     pubGet();
 
     d.packagesDir({"foo": "1.0.0"}).validate();
-    servePackages((builder) => builder.serve("foo", "1.0.1"));
+    globalPackageServer.add((builder) => builder.serve("foo", "1.0.1"));
     d.appDir({"foo": ">1.0.0"}).create();
 
     pubGet();
diff --git a/test/get/hosted/unlock_if_new_is_unsatisfied_test.dart b/test/get/hosted/unlock_if_new_is_unsatisfied_test.dart
index b824a2e8b..fd65adc52 100644
--- a/test/get/hosted/unlock_if_new_is_unsatisfied_test.dart
+++ b/test/get/hosted/unlock_if_new_is_unsatisfied_test.dart
@@ -26,7 +26,7 @@ main() {
       "qux": "1.0.0"
     }).validate();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("foo", "2.0.0", deps: {"bar": "<3.0.0"});
       builder.serve("bar", "2.0.0", deps: {"baz": "<3.0.0"});
       builder.serve("baz", "2.0.0", deps: {"qux": "<3.0.0"});
diff --git a/test/get/hosted/unlock_if_version_doesnt_exist_test.dart b/test/get/hosted/unlock_if_version_doesnt_exist_test.dart
index 371a780d0..c48f071fe 100644
--- a/test/get/hosted/unlock_if_version_doesnt_exist_test.dart
+++ b/test/get/hosted/unlock_if_version_doesnt_exist_test.dart
@@ -20,7 +20,7 @@ main() {
 
     schedule(() => deleteEntry(p.join(sandboxDir, cachePath)));
 
-    servePackages((builder) => builder.serve("foo", "1.0.1"), replace: true);
+    globalPackageServer.replace((builder) => builder.serve("foo", "1.0.1"));
     pubGet();
     d.packagesDir({"foo": "1.0.1"}).validate();
   });
diff --git a/test/list_package_dirs/lists_dependency_directories_test.dart b/test/list_package_dirs/lists_dependency_directories_test.dart
index 2fbcb9740..8001ca788 100644
--- a/test/list_package_dirs/lists_dependency_directories_test.dart
+++ b/test/list_package_dirs/lists_dependency_directories_test.dart
@@ -34,8 +34,9 @@ main() {
         outputJson: {
           "packages": {
             "foo": path.join(sandboxDir, "foo", "lib"),
-            "bar": port.then((p) => path.join(sandboxDir, cachePath, "hosted",
-                "localhost%58$p", "bar-1.0.0", "lib")),
+            "bar": globalServer.port.then(
+                (p) => path.join(sandboxDir, cachePath, "hosted",
+                    "localhost%58$p", "bar-1.0.0", "lib")),
             "myapp": canonicalize(path.join(sandboxDir, appPath, "lib"))
           },
           "input_files": [
diff --git a/test/serve_packages.dart b/test/package_server.dart
similarity index 68%
rename from test/serve_packages.dart
rename to test/package_server.dart
index 0c42da182..22aa83c1a 100644
--- a/test/serve_packages.dart
+++ b/test/package_server.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2016, 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.
 
@@ -15,61 +15,84 @@ import 'package:yaml/yaml.dart';
 import 'descriptor.dart' as d;
 import 'test_pub.dart';
 
-/// The [d.DirectoryDescriptor] describing the server layout of `/api/packages`
-/// on the test server.
-///
-/// This contains metadata for packages that are being served via
-/// [servePackages]. It's `null` if [servePackages] has not yet been called for
-/// this test.
-d.DirectoryDescriptor _servedApiPackageDir;
-
-/// The [d.DirectoryDescriptor] describing the server layout of `/packages` on
-/// the test server.
-///
-/// This contains the tarballs for packages that are being served via
-/// [servePackages]. It's `null` if [servePackages] has not yet been called for
-/// this test.
-d.DirectoryDescriptor _servedPackageDir;
+/// The current global [PackageServer].
+PackageServer get globalPackageServer => _globalPackageServer;
+PackageServer _globalPackageServer;
 
-/// The current [PackageServerBuilder] that a user uses to specify which package
-/// to serve.
-///
-/// This is preserved over multiple calls to [servePackages] within the same
-/// test so that additional packages can be added.
-PackageServerBuilder _builder;
-
-/// Creates an HTTP server that replicates the structure of pub.dartlang.org.
+/// Creates an HTTP server that replicates the structure of pub.dartlang.org and
+/// makes it the current [globalServer].
 ///
 /// Calls [callback] with a [PackageServerBuilder] that's used to specify
 /// which packages to serve.
+void servePackages(void callback(PackageServerBuilder builder)) {
+  _globalPackageServer = new PackageServer(callback);
+  globalServer = _globalPackageServer._inner;
+
+  currentSchedule.onComplete.schedule(() {
+    _globalPackageServer = null;
+  }, 'clearing the global package server');
+}
+
+/// Like [servePackages], but instead creates an empty server with no packages
+/// registered.
 ///
-/// If [replace] is false, subsequent calls to [servePackages] will add to the
-/// set of packages that are being served. Previous packages will continue to be
-/// served. Otherwise, the previous packages will no longer be served.
-void servePackages(void callback(PackageServerBuilder builder),
-    {bool replace: false}) {
-  if (_servedPackageDir == null) {
-    _builder = new PackageServerBuilder();
-    _servedApiPackageDir = d.dir('packages', []);
-    _servedPackageDir = d.dir('packages', []);
-    serve([
+/// This will always replace a previous server.
+void serveNoPackages() => servePackages((_) {}, replace: true);
+
+/// A shortcut for [servePackages] that serves the version of barback used by
+/// pub.
+void serveBarback() {
+  servePackages((builder) {
+    builder.serveRealPackage('barback');
+  });
+}
+
+class PackageServer {
+  /// The inner [DescriptorServer] that this uses to serve its descriptors.
+  DescriptorServer _inner;
+
+  /// The [d.DirectoryDescriptor] describing the server layout of
+  /// `/api/packages` on the test server.
+  ///
+  /// This contains metadata for packages that are being served via
+  /// [servePackages].
+  final _servedApiPackageDir = d.dir('packages', []);
+
+  /// The [d.DirectoryDescriptor] describing the server layout of `/packages` on
+  /// the test server.
+  ///
+  /// This contains the tarballs for packages that are being served via
+  /// [servePackages].
+  final _servedPackageDir = d.dir('packages', []);
+
+  /// The current [PackageServerBuilder] that a user uses to specify which
+  /// package to serve.
+  ///
+  /// This is preserved so that additional packages can be added.
+  var _builder = new PackageServerBuilder._();
+
+  /// Creates an HTTP server that replicates the structure of pub.dartlang.org.
+  ///
+  /// Calls [callback] with a [PackageServerBuilder] that's used to specify
+  /// which packages to serve.
+  PackageServer(void callback(PackageServerBuilder builder)) {
+    _inner = new DescriptorServer([
       d.dir('api', [_servedApiPackageDir]),
       _servedPackageDir
     ]);
 
-    currentSchedule.onComplete.schedule(() {
-      _builder = null;
-      _servedApiPackageDir = null;
-      _servedPackageDir = null;
-    }, 'cleaning up served packages');
+    add(callback);
   }
 
-  schedule(() {
-    if (replace) _builder = new PackageServerBuilder();
-    callback(_builder);
-    return _builder._await().then((resolvedPubspecs) {
+  /// Add to the current set of packages that are being served.
+  void add(void callback(PackageServerBuilder builder)) {
+    schedule(() async {
+      callback(_builder);
+
+      await _builder._await();
       _servedApiPackageDir.contents.clear();
       _servedPackageDir.contents.clear();
+
       _builder._packages.forEach((name, versions) {
         _servedApiPackageDir.contents.addAll([
           d.file('$name', JSON.encode({
@@ -91,22 +114,14 @@ void servePackages(void callback(PackageServerBuilder builder),
               d.tar('${version.version}.tar.gz', version.contents)))
         ]));
       });
-    });
-  }, 'initializing the package server');
-}
-
-/// Like [servePackages], but instead creates an empty server with no packages
-/// registered.
-///
-/// This will always replace a previous server.
-void serveNoPackages() => servePackages((_) {}, replace: true);
+    }, 'adding packages to the package server');
+  }
 
-/// A shortcut for [servePackages] that serves the version of barback used by
-/// pub.
-void serveBarback() {
-  servePackages((builder) {
-    builder.serveRealPackage('barback');
-  });
+  /// Replace the current set of packages that are being served.
+  void replace(void callback(PackageServerBuilder builder)) {
+    schedule(() => _builder._clear(), "clearing builder");
+    add(callback);
+  }
 }
 
 /// A builder for specifying which packages should be served by [servePackages].
@@ -119,6 +134,8 @@ class PackageServerBuilder {
   /// This should be accessed by calling [_awair].
   var _futures = new FutureGroup();
 
+  PackageServerBuilder._();
+
   /// Specifies that a package named [name] with [version] should be served.
   ///
   /// If [deps] is passed, it's used as the "dependencies" field of the pubspec.
@@ -188,6 +205,11 @@ class PackageServerBuilder {
       _futures = new FutureGroup();
     });
   }
+
+  /// Clears all existing packages from this builder.
+  void _clear() {
+    _packages.clear();
+  }
 }
 
 /// A package that's intended to be served.
diff --git a/test/snapshot/upgrades_snapshot_for_dependency_test.dart b/test/snapshot/upgrades_snapshot_for_dependency_test.dart
index 5ec2d4439..aec4b51b4 100644
--- a/test/snapshot/upgrades_snapshot_for_dependency_test.dart
+++ b/test/snapshot/upgrades_snapshot_for_dependency_test.dart
@@ -35,7 +35,7 @@ void main() => print(message);
       d.matcherFile('hello.dart.snapshot', contains('hello!'))
     ]).validate();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("bar", "1.2.4", contents: [
         d.dir("lib", [d.file("bar.dart", "final message = 'hello 2!';")]),
       ]);
diff --git a/test/snapshot/upgrades_snapshot_test.dart b/test/snapshot/upgrades_snapshot_test.dart
index 47ae92390..13baf3e5f 100644
--- a/test/snapshot/upgrades_snapshot_test.dart
+++ b/test/snapshot/upgrades_snapshot_test.dart
@@ -26,7 +26,7 @@ main() {
       d.matcherFile('hello.dart.snapshot', contains('hello!'))
     ]).validate();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("foo", "1.2.4", contents: [
         d.dir("bin", [
           d.file("hello.dart", "void main() => print('hello 2!');")
diff --git a/test/test_pub.dart b/test/test_pub.dart
index 1ef30206f..22da90d9b 100644
--- a/test/test_pub.dart
+++ b/test/test_pub.dart
@@ -35,22 +35,12 @@ import 'package:scheduled_test/scheduled_process.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 import 'package:scheduled_test/scheduled_stream.dart';
 import 'package:scheduled_test/scheduled_test.dart' hide fail;
-import 'package:shelf/shelf.dart' as shelf;
-import 'package:shelf/shelf_io.dart' as shelf_io;
 
 import 'descriptor.dart' as d;
+import 'descriptor_server.dart';
 
-export 'serve_packages.dart';
-
-/// The current [HttpServer] created using [serve].
-var _server;
-
-/// The list of paths that have been requested from the server since the last
-/// call to [getRequestedPaths].
-final _requestedPaths = <String>[];
-
-/// The cached value for [_portCompleter].
-Completer<int> _portCompleterCache;
+export 'descriptor_server.dart';
+export 'package_server.dart';
 
 /// A [Matcher] that matches JavaScript generated by dart2js with minification
 /// enabled.
@@ -66,91 +56,6 @@ Matcher isUnminifiedDart2JSOutput =
 final _entrypoint = new Entrypoint(
     pubRoot, new SystemCache.withSources(isOffline: true));
 
-/// The completer for [port].
-Completer<int> get _portCompleter {
-  if (_portCompleterCache != null) return _portCompleterCache;
-  _portCompleterCache = new Completer<int>();
-  currentSchedule.onComplete.schedule(() {
-    _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;
-
-/// Gets the list of paths that have been requested from the server since the
-/// last time this was called (or since the server was first spun up).
-Future<List<String>> getRequestedPaths() {
-  return schedule(() {
-    var paths = _requestedPaths.toList();
-    _requestedPaths.clear();
-    return paths;
-  }, "get previous network requests");
-}
-
-/// 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] replace the previous server.
-void serve([List<d.Descriptor> contents]) {
-  var baseDir = d.dir("serve-dir", contents);
-
-  _hasServer = true;
-
-  schedule(() {
-    return _closeServer().then((_) {
-      return shelf_io.serve((request) {
-        var path = p.posix.fromUri(request.url.path);
-        _requestedPaths.add(path);
-
-        return validateStream(baseDir.load(path))
-            .then((stream) => new shelf.Response.ok(stream))
-            .catchError((error) {
-          return new shelf.Response.notFound('File "$path" not found.');
-        });
-      }, 'localhost', 0).then((server) {
-        _server = server;
-        _portCompleter.complete(_server.port);
-        currentSchedule.onComplete.schedule(_closeServer);
-      });
-    });
-  }, 'starting a server serving:\n${baseDir.describe()}');
-}
-
-/// Like [serve], but reports an error if a request ever comes in to the server.
-void serveErrors() {
-  _hasServer = true;
-
-  schedule(() async {
-    await _closeServer();
-
-    _server = await shelf_io.serve((request) {
-      fail("The HTTP server received an unexpected request:\n"
-          "${request.method} ${request.requestedUri}");
-      return new shelf.Response.forbidden(null);
-    }, 'localhost', 0);
-
-    _portCompleter.complete(_server.port);
-    currentSchedule.onComplete.schedule(_closeServer);
-  });
-}
-
-/// Closes [_server].
-///
-/// Returns a [Future] that completes after the [_server] is closed.
-Future _closeServer() {
-  if (_server == null) return new Future.value();
-  var future = _server.close();
-  _server = null;
-  _hasServer = false;
-  _portCompleterCache = null;
-  return future;
-}
-
-/// `true` if the current test spins up an HTTP server.
-bool _hasServer = false;
-
 /// Converts [value] into a YAML string.
 String yaml(value) => JSON.encode(value);
 
@@ -405,8 +310,9 @@ Future<Map> getPubTestEnvironment([String tokenEndpoint]) async {
     environment['_PUB_TEST_TOKEN_ENDPOINT'] = tokenEndpoint.toString();
   }
 
-  if (_hasServer) {
-    environment['PUB_HOSTED_URL'] = "http://localhost:${await port}";
+  if (globalServer != null) {
+    environment['PUB_HOSTED_URL'] =
+        "http://localhost:${await globalServer.port}";
   }
 
   return environment;
diff --git a/test/transformer/cache_test.dart b/test/transformer/cache_test.dart
index 85c02421c..b653db116 100644
--- a/test/transformer/cache_test.dart
+++ b/test/transformer/cache_test.dart
@@ -171,7 +171,7 @@ main() {
       ])
     ]).validate();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("foo", "2.0.0",
           deps: {'barback': 'any'},
           contents: [
@@ -242,7 +242,7 @@ main() {
     process.stdout.expect("Goodbye!");
     process.shouldExit();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("bar", "2.0.0", contents: [
         d.dir("lib", [
           d.file("bar.dart", "final replacement = 'See ya';")
diff --git a/test/upgrade/hosted/unlock_dependers_test.dart b/test/upgrade/hosted/unlock_dependers_test.dart
index 7a4a1ea8f..11dcc3cd8 100644
--- a/test/upgrade/hosted/unlock_dependers_test.dart
+++ b/test/upgrade/hosted/unlock_dependers_test.dart
@@ -22,7 +22,7 @@ main() {
       "bar": "1.0.0"
     }).validate();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("foo", "2.0.0", deps: {"bar": "<3.0.0"});
       builder.serve("bar", "2.0.0");
     });
diff --git a/test/upgrade/hosted/unlock_if_necessary_test.dart b/test/upgrade/hosted/unlock_if_necessary_test.dart
index ed38adf12..1b0150706 100644
--- a/test/upgrade/hosted/unlock_if_necessary_test.dart
+++ b/test/upgrade/hosted/unlock_if_necessary_test.dart
@@ -22,7 +22,7 @@ main() {
       "foo_dep": "1.0.0"
     }).validate();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("foo", "2.0.0", deps: {"foo_dep": ">1.0.0"});
       builder.serve("foo_dep", "2.0.0");
     });