public void OperationStart_CorrectEventContent()
{
var source = new DiagnosticListener("Autofac");
var subscriber = new MockSubscriber();
subscriber.Enable(DiagnosticEventKeys.OperationStart);
source.Subscribe(subscriber, subscriber.IsEnabled);
var operation = MockResolveOperation();
var request = MockResolveRequest();
source.OperationStart(operation, request);
var e = Assert.Single(subscriber.Events);
Assert.Equal(DiagnosticEventKeys.OperationStart, e.Key);
Assert.IsType <OperationStartDiagnosticData>(e.Value);
}