public async Task CreateNewShouldWriteToDisk()
{
var subject = Arrange();
SetPrivateBudgetCollection(subject);
var filename = "FooBar.xml";
await subject.CreateNewAndSaveAsync(filename);
this.mockFileSelector.Verify(m => m.SelectReaderWriter(It.IsAny<bool>()));
this.mockReaderWriter.Verify(m => m.WriteToDiskAsync(It.IsAny<string>(), It.IsAny<string>()));
}