public void MiddlewareStart_CorrectEventContent()
{
var source = new DiagnosticListener("Autofac");
var subscriber = new MockSubscriber();
subscriber.Enable(DiagnosticEventKeys.MiddlewareStart);
source.Subscribe(subscriber, subscriber.IsEnabled);
var context = MockResolveRequestContext();
source.MiddlewareStart(context, Mock.Of <IResolveMiddleware>());
var e = Assert.Single(subscriber.Events);
Assert.Equal(DiagnosticEventKeys.MiddlewareStart, e.Key);
Assert.IsType <MiddlewareDiagnosticData>(e.Value);
}