More unit tests and a $.hasData that works for JS objects too.

src/data.js

@@ -22,7 +22,11 @@ jQuery.extend({
 	},
 
 	hasData: function( elem ) {
-		return !elem.nodeType || (!!elem[ jQuery.expando ] && !jQuery.isEmptyObject(jQuery.cache[ elem[jQuery.expando] ]));
+		if (elem.nodeType) {
+			elem = jQuery.cache[ elem[jQuery.expando] ];
+		}
+
+		return !!elem && !jQuery.isEmptyObject(elem);
 	},
 
 	data: function( elem, name, data ) {

test/unit/data.js

@@ -79,12 +79,18 @@ test("jQuery.data", function() {
 });
 
 test("jQuery.hasData", function() {
-	var div = document.createElement( "div" );
-	equals( jQuery.hasData(div), false, "No data exists" );
-	jQuery.data( div, "foo", "bar" );
-	equals( jQuery.hasData(div), true, "Data exists" );
-	jQuery.removeData( div, "foo" );
-	equals( jQuery.hasData(div), false, "Data was removed" );
+	expect(6);
+
+	function testData(obj) {
+		equals( jQuery.hasData(obj), false, "No data exists" );
+		jQuery.data( obj, "foo", "bar" );
+		equals( jQuery.hasData(obj), true, "Data exists" );
+		jQuery.removeData( obj, "foo" );
+		equals( jQuery.hasData(obj), false, "Data was removed" );
+	}
+
+	testData(document.createElement('div'));
+	testData({});
 });
 
 test(".data()", function() {