How do you run `go test` when test files are within a module?

When you have pulled in a module, into your project, how do you run test cases within that module?

i.e. I have done:

go get http://ift.tt/2b17xYI

And then try to test something in it:

server> go test src/http://ift.tt/2bDu82F 
# command-line-arguments
src/http://ift.tt/2b17zQk: cannot find package "mymodule" in any of:

Are we supposed to check out our modules separately and test that way? I can't quite work out what to do. It seems that when I go run it knows how to find the module I have fetched, but when I go test, it "can't find it" in the path.