Inter-service Communication Architecture Using WCF, Dependency Injection, and Unit Testing

Question

I'm new to WCF and in a large part, also distributed programming. I am working on a project that requires 4 discrete services.

I am trying to correctly define the responsibilities for each component of each service. Suppose I have service B which needs to communicate with service A. For each service, I have defined the service implementation class, the service host, and a proxy class.

In order to unit test, I am using dependency injection - since service B needs to communicate with service A, I have passed an instance of A's proxy class as a constructor argument to service B.

When I am unit testing service B, I must have A's service host up and running.

1. Is this the wrong way of going about dependency injection? If so, why, and how do you recommend I do it?
2. Is there a better way of going about dependency injection?
3. Should I have to run the service host to get the right results in the unit test?

Answer 1

Consider using

• ChannelFactory instead of generated clients.

   ChannelFactory<IHello> clientFactory = new ChannelFactory<IHello>("targetConfiguration"); IHello client = clientFactory.CreateChannel(); string result = client.SayHello(); 

• Interface types wherever possible

• one of the mock object frameworks ( example ) to inject interface implementations when writing your tests.

Regarding your third question, the answer is "No" if your aim is testing particular small units (the whole point of unit testing :). But it's always better to write some integration tests to make sure you don't have any serialization/hosting problems.