Go doesn't have any mocking framework like Mockito/Java or Rspec mock. You will end up writing a ton of code yourself if you want to mock something simple.
I've only dabbled a bit but I haven't seen a DSL that easily creates a mock that implements all the methods of a given interface, verifies that methods were (not) called with expected arguments, and returns or throws canned values. It's not difficult to write mocks from scratch, but it's very repetitive and hard to skim what the test does.
That's what the other gophers say too. Java has interfaces too, but it also has Mockito that makes testing much easier. You should look into it. Mocking library will help reduce boiler code. You would know that if you had used one.
