Tell the user if the binstub directory is not on their path.

sdk/lib/_internal/pub/test/global/binstubs/does_not_warn_if_no_executables_test.dart

Index: sdk/lib/_internal/pub/test/global/binstubs/does_not_warn_if_no_executables_test.dart
diff --git a/sdk/lib/_internal/pub/test/global/run/runs_script_test.dart b/sdk/lib/_internal/pub/test/global/binstubs/does_not_warn_if_no_executables_test.dart
similarity index 55%
copy from sdk/lib/_internal/pub/test/global/run/runs_script_test.dart
copy to sdk/lib/_internal/pub/test/global/binstubs/does_not_warn_if_no_executables_test.dart
index bfd8bcbffbd242d8dbea10fea0b8ba706bd4d9d7..565e23afbdcc4e7f6d6e9fc5f4cb6f5da53290ba 100644
--- a/sdk/lib/_internal/pub/test/global/run/runs_script_test.dart
+++ b/sdk/lib/_internal/pub/test/global/binstubs/does_not_warn_if_no_executables_test.dart
@@ -2,24 +2,26 @@
 // 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:io';
+
+import 'package:path/path.dart' as p;
+import 'package:scheduled_test/scheduled_test.dart';
+
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 main() {
   initConfig();
-  integration('runs a script in an activated package', () {
+  integration("does not warn if the package has no executables", () {
     servePackages((builder) {
       builder.serve("foo", "1.0.0", contents: [
         d.dir("bin", [
-          d.file("script.dart", "main(args) => print('ok');")
+          d.file("script.dart", "main(args) => print('ok \$args');")
         ])
       ]);
     });
 
-    schedulePub(args: ["global", "activate", "foo"]);
-
-    var pub = pubRun(global: true, args: ["foo:script"]);
-    pub.stdout.expect("ok");
-    pub.shouldExit();
+    schedulePub(args: ["global", "activate", "foo"],
+        output: isNot(contains("is not on your path")));
   });
-}
+}