I wondering if we couldn't have something more systematic and have
this done, for all the available cluster RPC methods, in the base test
class (and for every cluster created in the tests). Of course you'll
have to configure mock objects if you're expecting a particular
response from one of the RPC methods. But if all you need is the code
not to blow up because a cluster RPC method has been called as a
side-effect of what you're actually testing, this will be taken care
of.
If we get to the point where we're stubbing out more than 2 or 3 RPC
calls in a test then we're not writing a unit test any more. The desire
for a does-all-the-things mock cluster might be a manifestation of
writing overly broad tests, or of not writing small enough units of
testable code. Equally, having a does-all-the-things mock makes it
easier to write overly broad tests and overly large units of code.
Fwiw, I think signals in model code can contribute to this: tests always
have to deal with side-effects from signals, which now might include
RPC. I liked the way that we dealt with needing side-effects as a result
of model changes in Launchpad: enforce use of a mutator method and
forbid use of the model attribute from view/controller code. We could
test the mutator, its use was explicit, but we could bypass it when
setting up tests.
