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

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

Index: sdk/lib/_internal/pub/test/global/binstubs/does_not_warn_if_on_path_test.dart
diff --git a/sdk/lib/_internal/pub/test/global/binstubs/does_not_warn_if_on_path_test.dart b/sdk/lib/_internal/pub/test/global/binstubs/does_not_warn_if_on_path_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..124d1679bd4fced8ab536167509c25a45bc70313
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/global/binstubs/does_not_warn_if_on_path_test.dart
@@ -0,0 +1,37 @@
+// 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 '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("does not warn if the binstub directory is on the path", () {
+    servePackages((builder) {
+      builder.serve("foo", "1.0.0", pubspec: {
+        "executables": {
+          "script": null
+        }
+      }, contents: [
+        d.dir("bin", [
+          d.file("script.dart", "main(args) => print('ok \$args');")
+        ])
+      ]);
+    });
+
+    // Add the test's cache bin directory to the path.
+    var binDir = p.dirname(Platform.executable);
+    var separator = Platform.operatingSystem == "windows" ? ";" : ":";
+    var path = "${Platform.environment["PATH"]}$separator$binDir";
+
+    schedulePub(args: ["global", "activate", "foo"],
+        output: isNot(contains("is not on your path")),
+        environment: {"PATH": path});
+  });
+}