"Multiple serializers are not supported" configuration error in NServiceBus 4.0.4 during unit testing

Question

I am trying to unit test message handlers for NServiceBus 4.0.4. The bus is configured to use JSON serializer in the application using the Configure.Serialization.Json(); method call.

Whenever I call the Test.Initialize() method from the unit tests assembly I get the following exception: System.Configuration.ConfigurationErrorsException : Multiple serializers are not supported. Please make sure to only enable one

I tried calling Configure.Serialization.Json() and Serializers.SetDefault<JsonSerialization>() before calling the Test.Initialize() method without any success.

Does anyone know what am I doing wrong? All examples I see on the internet do not mention any Configure calls.

Answer 1

This issue has been reported previously here and looks like it will be fixed in the next NServiceBus build (both 4.0.5 and 4.1.0)

A workaround is to explicitly disable the xml serializer when enabling the json one.

Configure.Serialization.Json();
Feature.Disable<XmlSerialization>(); // hack to make NSB unit tests work