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.