You're right that there is some overlap between the tests.  I have tended to think of the tests against the *core* as being more *unit* level vs. the tests which bootstrap trapperkeeper and the services as being more *component* level.  Across testing tiers, I think some overlap will happen.  For this PR, the failure tests at the *unit* level are more exhaustive than those at the *component* level.  I had thought to only go so far as to cover the more common success and failure cases at the *component* level.  I could cut a couple of the *component* level tests out if you have a strong opinion about this but my preference would be to keep the tests as written.