def METHOD_NAME(subdomain):
    from os.path import abspath, dirname, join
    mesh = Mesh(join(abspath(dirname(__file__)), "..",
                     "meshes", "cell-sets.msh"))
    V = FunctionSpace(mesh, "DG", 0)
    expect = interpolate(as_ufl(1), V, subset=mesh.cell_subset(subdomain))
    f = Function(V)
    domain = "{[i]: 0 <= i < f.dofs}"
    instructions = """
    for i
        f[i, 0] = 1.0
    end
    """
    par_loop((domain, instructions), dx(subdomain), {'f': (f, WRITE)})
    assert np.allclose(f.dat.data, expect.dat.data)