public void TestHasThemes()
{
Assert.IsNull(configuration.ThemesDelegate);
configuration.HasThemes(x => x.Themes);
Assert.IsNotNull(configuration.ThemesDelegate);
var instance = new TestDocument();
instance.Themes = new string[] { "value1", "value2" };
Assert.IsTrue(Object.ReferenceEquals(instance.Themes, configuration.ThemesDelegate(instance)));
}