Create binstubs for executables when activating a package.

sdk/lib/_internal/pub/lib/src/validator/executable.dart

+// Copyright (c) 2012, 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.
+
+library pub.validator.compiled_dartdoc;
+
+import 'dart:async';
+
+import 'package:path/path.dart' as p;
+
+import '../entrypoint.dart';
+import '../io.dart';
+import '../utils.dart';
+import '../validator.dart';
+
+/// Validates that a package's pubspec doesn't contain executables that
+/// reference non-existent scripts.
+class ExecutableValidator extends Validator {
+  ExecutableValidator(Entrypoint entrypoint)
+    : super(entrypoint);
+
+  Future validate() async {
+    // TODO(rnystrom): This can print false positives since a script may be
+    // produced by a transformer. Do something better.
+    var binFiles = entrypoint.root.listFiles(beneath: "bin", recursive: false)
+        .map((path) => p.relative(path, from: entrypoint.root.dir))
+        .toList();
+
+    entrypoint.root.pubspec.executables.forEach((executable, script) {
+      if (!binFiles.contains("bin/$script.dart")) {

[nweiz, 2014/09/17 22:58:27]

Use p.join here. Also maybe short-circuit rather than nesting.

[Bob Nystrom, 2014/09/18 19:17:53]

Done.

+        warnings.add('Your pubspec.yaml lists an executable "$executable" that '
+            'points to a script "bin/$script.dart" that does not exist.');

[nweiz, 2014/09/17 22:58:27]

Use p.join here as well to give native-feeling paths.

[Bob Nystrom, 2014/09/18 19:17:53]

Done.

+      }
+    });
+  }
+}