Add a hidden --no-package-symlinks flag.

sdk/lib/_internal/pub/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([
+          packageMap("foo", "1.0.0"),
+          packageMap("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();
+      });
+    });
+  });
+}