public void AsCssData_Test()
{
var prop1CssData = new CssData();
prop1CssData.AddAttribute(".test", "color", "red");
prop1CssData.AddAttribute(".test", "", "red");
var prop1 = Substitute.For <ICssProperty>();
prop1
.When(x => x.InsertCss(Arg.Any <CssPropertiesSet>(), Arg.Any <CssData>()))
.Do(x => x.ArgAt <CssData>(1).AddRange(prop1CssData));
_instance.Add(prop1);
_instance.Selector = ".test";
var r = new CssData();
_instance.InsertCss(r);
Assert.AreEqual(prop1CssData, r);
prop1.Received(1).Selector = ".test";
}