def test_fetch_op():
a0 = np.zeros(1, dtype=INT64)
a1 = np.zeros(1, dtype=INT64)
b0 = np.zeros(1, dtype=INT64)
b1 = np.zeros(MPISIZE, INT64)
a0[:] = 1
a1[:] = -1
b1[:] = -1
comm = MPI.COMM_WORLD
gwin = MPI.Win()
win = gwin.Create(b0, b0[0].nbytes, comm=comm)
comm.Barrier()
win.Fence()
win.Fetch_and_op(a0, a1, 0, 0)
win.Fence()
comm.Barrier()
comm.Gather(a1, b1)
comm.Barrier()
if MPIRANK == 0:
assert b0[0] == MPISIZE
required = set(range(MPISIZE))
for bx in b1:
required.remove(bx)
assert len(required) == 0
