public void GetExtension_Returns_CorrectValue()
        {
            var model = new AddFolderOptionsViewModel(_window, _fileUploader);

            model.SelectedFileTypeIndex = 0;
            Assert.That(model.GetExtension(), Is.Empty);

            model.SelectedFileTypeIndex = 1;
            Assert.That(model.GetExtension(), Is.Empty);

            model.SelectedFileTypeIndex = 2;
            Assert.That(model.GetExtension(), Is.Empty);

            model.SelectedFileTypeIndex = 3;
            Assert.That(model.GetExtension(), Is.EqualTo("FOO"));
        }