QUnit test for overriding important css declarations, references #4427

test/data/testsuite.css

@@ -109,3 +109,7 @@ div#show-tests * { display: none; }
 #nothiddendiv { font-size: 16px; }
 #nothiddendivchild.em { font-size: 2em; }
 #nothiddendivchild.prct { font-size: 150%; }
+
+div.isimportant {
+    background-color: rgb(255, 255, 255) !important;
+}

test/unit/css.js

@@ -377,3 +377,18 @@ test("marginRight computed style (bug #3333)", function() {
 
 	equals($div.css("marginRight"), "0px", "marginRight correctly calculated with a width and display block");
 });
+
+test("$().css override !important css declarations (bug #4427)", function(){
+	expect(4);
+	var div = jQuery("<div/>", {
+		"class": "isimportant" // background-color: #fff !important
+	});
+	div.css("backgroundColor", "rgb(0, 255, 0)");
+	equals( div.css("backgroundColor"), "rgb(0, 255, 0)", "Background color is overrided to rgb(0, 255, 0)" );
+	equals( div.css("background-color"), "rgb(0, 255, 0)", "Background color is overrided to rgb(0, 255, 0)"  );
+
+	div.css("background-color", "rgb(0, 255, 0)");
+	equals( div.css("backgroundColor"), "rgb(0, 255, 0)", "Background color is overrided to rgb(0, 255, 0)"  );
+	equals( div.css("background-color"), "rgb(0, 255, 0)", "Background color is overrided to rgb(0, 255, 0)"  );
+
+});