Validate that a package doesn't depend on itself.

BUG=7045

Review URL: https://codereview.chromium.org//11737013

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@16614 260f80e4-7a28-3924-810f-c04153c831b5

utils/pub/validator/dependency.dart

@@ -23,6 +23,14 @@ class DependencyValidator extends Validator {
         return _warnAboutSource(dependency);
       }
 
+      if (dependency.name == entrypoint.root.name) {
+        warnings.add('You don\'t need to explicitly depend on your own '
+                'package.\n'
+            'Pub enables "package:${entrypoint.root.name}" imports '
+                'implicitly.');
+        return new Future.immediate(null);
+      }
+
       if (dependency.constraint.isAny &&
           // TODO(nweiz): once we have development dependencies (issue 5358), we
           // should warn about unittest. Until then, it's reasonable not to put

utils/tests/pub/validator_test.dart

@@ -531,5 +531,17 @@ main() {
         });
       });
     });
+
+    test('has a hosted dependency on itself', () {
+      dir(appPath, [
+        libPubspec("test_pkg", "1.0.0", [
+          {'hosted': {'name': 'test_pkg', 'version': '>=1.0.0'}}
+        ])
+      ]).scheduleCreate();
+
+      expectValidationWarning(dependency);
+
+      run();
+    });
   });
 }