Hosting a WCF service in a unit test - wcf

Question

I'm wanting to unit test my custom ServiceHostFactory. Unfortunately, I get this InvalidOperationException when calling CreateServiceHost:
'ServiceHostFactory.CreateServiceHost' cannot be invoked within the current hosting environment. This API requires that the calling application be hosted in IIS or WAS.
I can work around this by refactoring my class such that it exposes a public method that can be directly invoked by the unit test instead of using its inherited public interface; I hate to change my interface just for the sake of a unit test. I also see another SO answer that recommends spawning a Cassini host, but I'd hate to complicate my unit tests in this manner.
Is there a way to work around this ServiceHostFactory limitation without resorting to these measures?

Answer 1

I figured out the issue. In my custom ServiceHostFactory, I had only overridden the protected method, CreateServiceHost(Type serviceType, Uri[] baseAddresses). By overriding the public CreateServiceHost(string constructorString, Uri[] baseAddresses) method, I was able to construct the service host factory with no issues.
Before:
public class MyServiceHostFactory : ServiceHostFactory
{
protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses)
{
// ...
}
}
After:
public class MyServiceHostFactory : ServiceHostFactory
{
public override ServiceHostBase CreateServiceHost(string constructorString, Uri[] baseAddresses)
{
return this.CreateServiceHost(typeof(MyService), baseAddresses);
}
protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses)
{
// ...
}
}

Answer 2

Here is my solution to this problem (I am not 100% sure whether we should be doing this).
In the set up of the unit test fixture, set up a hosting environment (NUnit example):
[TestFixtureSetUp]
public void TestFixtureSetup()
{
if(!HostingEnvironment.IsHosted)
{
// The instance constructor hooks up the singleton hosting environment, ewww...
new HostingEnvironment();
// Check the hosting environment is fully initialized
ServiceHostingEnvironment.EnsureInitialized();
}
}
Then you should be free to use your custom ServiceHostFactory from inside of your unit tests:
[Test]
public void ServiceHostIsCorrect()
{
// Arrange
var serviceType = typeof (string);
var factory = new UnityServiceHostFactory();
// Act
var serviceHost = factory.CreateServiceHost(serviceType.AssemblyQualifiedName, new Uri[] {});
// Assert
Expect(serviceHost, Is.TypeOf<UnityServiceHost>());
var unityServiceHost = (UnityServiceHost)serviceHost;
Expect(unityServiceHost.Description.ServiceType, Is.EqualTo(serviceType));
}