If your default preference under Locations -> Derived Data -> Advanced is to use the Legacy build location (which places the build in the project directory), the published instructions don't allow you to actually compile the integration test project without receiving a linker error.
Proposed fix is to mention this in the documentation. I changed my Derived Data build location to "Unique" and that resolved the issue. This may be one of the reasons why so many people are encountering this issue: #44
Closing due to age.