public async void TestAdd()
{
await this.SetUp();
var item = new FileExtensionsItem(null);
item.Extension = ".csv";
_feature.AddItem(item);
Assert.NotNull(_feature.SelectedItem);
Assert.Equal(".csv", _feature.SelectedItem.Extension);
const string Original = @"original.config";
const string OriginalMono = @"original.mono.config";
XmlAssert.Equal(Helper.IsRunningOnMono() ? OriginalMono : Original, Current);
XmlAssert.Equal(Path.Combine("RequestFiltering", "FileExtensions", "expected_add.site.config"), Path.Combine("Website1", "web.config"));
}