Refactor test servers to make them less global.

This sets the stage for adding tests for #1386.

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//1664563002 .

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")

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")

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)))
     ])
   ]);
 }

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");
+  }
+}

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");
     });

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");
     });

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.")));
   });
 

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",

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")));
     });
   });

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);
     });
   });

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();
 

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");

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();

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();

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"});

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();
   });

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": [