How to get the message handler from the service provider ?

[Anthony-Breneliere]

Hello,

I recently added RabbitMQ.Client.Core.DependencyInjection project in replacement of RabbitMQ.Client.

For unit testing, I need to get a specific handler from the service provider, that I have injected in my app's startup with the command: .AddMessageHandlerSingleton<CustomMessageHandler>("routing.key");

How to do it ?