The fixture’s on-board imp is not a factory imp until it’s actually set as one in the target Production Model, so these tests will fail until (a) you make that assignment and (b) you deploy a promoted version of the code to that factory imp.
You can still test your factory firmware, but just work around those calls - just as you need to do for server.bless() and server.factoryblinkup().
Couple of additional things. First, impCentral is going to make all this a lot easier (it has a full factory test capability) and, second, just in case you’re using an imp001 card in your fixture, please bear in mind that this will not be supported from December 4, 2017, so you should switch to a fixture based on an imp module. If you’re already doing that, there’s no need to make any hardware changes.