Track Source objects in PackageNames.

lib/src/validator/dependency.dart

Index: lib/src/validator/dependency.dart
diff --git a/lib/src/validator/dependency.dart b/lib/src/validator/dependency.dart
index e00879ca9ebbc3fccc5008a1ab88a3f6bd234d02..9d14476f9239dca9ca45bc47a7adff8a679a88d5 100644
--- a/lib/src/validator/dependency.dart
+++ b/lib/src/validator/dependency.dart
@@ -9,6 +9,8 @@ import 'package:pub_semver/pub_semver.dart';
 import '../entrypoint.dart';
 import '../log.dart' as log;
 import '../package.dart';
+import '../source/hosted.dart';
+import '../source/path.dart';
 import '../validator.dart';
 
 /// The range of all pub versions that don't support `^` version constraints.
@@ -37,7 +39,7 @@ class DependencyValidator extends Validator {
     var caretDeps = [];
 
     for (var dependency in entrypoint.root.pubspec.dependencies) {
-      if (dependency.source != "hosted") {
+      if (dependency.source is! HostedSource) {
         await _warnAboutSource(dependency);
       } else if (dependency.constraint.isAny) {
         _warnAboutNoConstraint(dependency);
@@ -84,10 +86,7 @@ class DependencyValidator extends Validator {
     }
 
     // Path sources are errors. Other sources are just warnings.
-    var messages = warnings;
-    if (dep.source == "path") {
-      messages = errors;
-    }
+    var messages = dep.source is PathSource ? errors : warnings;
 
     messages.add('Don\'t depend on "${dep.name}" from the ${dep.source} '
             'source. Use the hosted source instead. For example:\n'