We currently have a quite low test coverage in the PETSc radial-basis function mapping.

To be more precise, we only test the Tree preallocation strategy. All remaining strategies Compute, Save, Estimate, None are not tested at all.

See the file on [CodeCov](https://codecov.io/gh/precice/prec

The actual ghostUpdate is truly needed only in very few places, for most local operations one knows the value for ghosts without communication.

This

u.vector.copy(result=u0.vector)
u0.vector.ghostUpdate(addv=PETSc.InsertMode.INSERT, mode=PETSc.ScatterMode.FORWARD)

could become

with u0.vector.localForm() as loc0, u.vector.localForm() as loc:
    loc.copy(loc0)
``