Create binstubs for executables when activating a package.

sdk/lib/_internal/pub/test/global/binstubs/missing_script_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_stream.dart';
+
+import '../../../lib/src/exit_codes.dart' as exit_codes;
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+
+main() {
+  initConfig();
+  integration("errors if an executable's script can't be found", () {
+    d.dir("foo", [
+      d.pubspec({
+        "name": "foo",
+        "executables": {
+          "missing": "not_here",
+          "nope": null
+        }
+      })
+    ]).create();
+
+    var pub = startPub(args: ["global", "activate", "-spath", "../foo"]);
+
+    pub.stderr.expect('Warning: Executable "missing" runs '
+        '"bin/not_here.dart", which was not found in foo.');
+    pub.stderr.expect('Warning: Executable "nope" runs "bin/nope.dart", which '
+        'was not found in foo.');
+    pub.shouldExit();
+  });
+}