add basic tests for both methods

Author: IanButterworth

test/distributed_exec.jl

@@ -718,6 +718,8 @@ wp = WorkerPool(workers())
 @test nworkers() == length(unique(remotecall_fetch(wp->pmap(_->myid(), wp, 1:100), id_other, wp)))
 wp = WorkerPool(2:3)
 @test sort(unique(pmap(_->myid(), wp, 1:100))) == [2,3]
+@test fetch(remotecall(myid, wp)) in wp.workers
+@test_throws RemoteException fetch(remotecall(error, wp))
 
 # wait on worker pool
 wp = WorkerPool(2:2)
@@ -743,6 +745,8 @@ status = timedwait(() -> isready(f), 10)
 # CachingPool tests
 wp = CachingPool(workers())
 @test [1:100...] == pmap(x->x, wp, 1:100)
+@test fetch(remotecall(myid, wp)) in wp.workers
+@test_throws RemoteException fetch(remotecall(error, wp))
 
 clear!(wp)
 @test length(wp.map_obj2ref) == 0