Parallel processing queue [on hold]

I would like to write unit test cases for the message consumer. Message consumer will be of key value type. Each unit test will have a string as key. From consumer, message will be pushed to a queue. That event should be listened by each unit test cases. Whenever the appropriate key is added to this queue that particular unit test should start asserting. Could anyone suggest which C# queue type or mechanism I can use for this scenario. Thanks in advance.