public void ShouldCallCollectOnCollector()
{
var collector = new Mock <IMetadataCollector <long> >();
var handler = new TestHandler();
handler.AddCollector <IMetadataCollector <long>, long>(collector.Object);
var metadata = new Dictionary <string, object> {
{ "x", 1 }, { "y", false }
};
handler.OnSuccess(metadata);
collector.Verify(x => x.Collect(metadata), Times.Once);
}