Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/no_package_symlinks_test.dart

-// Copyright (c) 2014, 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 'package:scheduled_test/scheduled_test.dart';
-
-import 'descriptor.dart' as d;
-import 'test_pub.dart';
-
-main() {
-  initConfig();
-
-  forBothPubGetAndUpgrade((command) {
-    group("with --no-package-symlinks", () {
-      integration("installs hosted dependencies to the cache", () {
-        servePackages((builder) {
-          builder.serve("foo", "1.0.0");
-          builder.serve("bar", "1.0.0");
-        });
-
-        d.appDir({
-          "foo": "any",
-          "bar": "any"
-        }).create();
-
-        pubCommand(command, args: ["--no-package-symlinks"]);
-
-        d.nothing("$appPath/packages").validate();
-
-        d.hostedCache(
-            [
-                d.dir(
-                    "foo-1.0.0",
-                    [d.dir("lib", [d.file("foo.dart", 'main() => "foo 1.0.0";')])]),
-                d.dir(
-                    "bar-1.0.0",
-                    [d.dir("lib", [d.file("bar.dart", 'main() => "bar 1.0.0";')])])]).validate();
-      });
-
-      integration("installs git dependencies to the cache", () {
-        ensureGit();
-
-        d.git(
-            'foo.git',
-            [d.libDir('foo'), d.libPubspec('foo', '1.0.0')]).create();
-
-        d.appDir({
-          "foo": {
-            "git": "../foo.git"
-          }
-        }).create();
-
-        pubCommand(command, args: ["--no-package-symlinks"]);
-
-        d.nothing("$appPath/packages").validate();
-
-        d.dir(
-            cachePath,
-            [
-                d.dir(
-                    'git',
-                    [
-                        d.dir('cache', [d.gitPackageRepoCacheDir('foo')]),
-                        d.gitPackageRevisionCacheDir('foo')])]).validate();
-      });
-
-      integration("locks path dependencies", () {
-        d.dir("foo", [d.libDir("foo"), d.libPubspec("foo", "0.0.1")]).create();
-
-        d.dir(appPath, [d.appPubspec({
-            "foo": {
-              "path": "../foo"
-            }
-          })]).create();
-
-        pubCommand(command, args: ["--no-package-symlinks"]);
-
-        d.nothing("$appPath/packages").validate();
-        d.matcherFile("$appPath/pubspec.lock", contains("foo"));
-      });
-
-      integration("removes package directories near entrypoints", () {
-        d.dir(
-            appPath,
-            [
-                d.appPubspec(),
-                d.dir("packages"),
-                d.dir("bin/packages"),
-                d.dir("web/packages"),
-                d.dir("web/subdir/packages")]).create();
-
-        pubCommand(command, args: ["--no-package-symlinks"]);
-
-        d.dir(
-            appPath,
-            [
-                d.nothing("packages"),
-                d.nothing("bin/packages"),
-                d.nothing("web/packages"),
-                d.nothing("web/subdir/packages")]).validate();
-      });
-
-      integration(
-          "doesn't remove package directories that pub wouldn't " "generate",
-          () {
-        d.dir(
-            appPath,
-            [
-                d.appPubspec(),
-                d.dir("packages"),
-                d.dir("bin/subdir/packages"),
-                d.dir("lib/packages")]).create();
-
-        pubCommand(command, args: ["--no-package-symlinks"]);
-
-        d.dir(
-            appPath,
-            [
-                d.nothing("packages"),
-                d.dir("bin/subdir/packages"),
-                d.dir("lib/packages")]).validate();
-      });
-    });
-  });
-}