I have two services that communicate over the network. Neither does anything useful without data from the other. So I write my tests like this article suggests

I have two services that communicate over the network. Neither does anything useful without data from the other. So I write my tests like this article suggests and inject at the boundaries of the services, the network boundary in this case. I've built tests that now only test my idea of what the services will return. IMO these aren't particularly useful tests: what happens when the remote service starts returning unexpected data or errors due load problems? I guess my point is just this article is good advice: prefer testing your actual code and dependencies, but unit testing isn't a replacement for integration testing.