Fix healpy optional dep in test_re

Dockerfile

@@ -12,7 +12,7 @@ RUN pip3 install --break-system-packages \
     # Packages needed for NIFTy
     scipy \
     # Optional nifty dependencies
-    matplotlib h5py astropy ducc0 jax jaxlib jaxbind mpi4py \
+    matplotlib h5py astropy ducc0 jax jaxlib jaxbind mpi4py healpy \
     # Testing dependencies
     pytest pytest-cov pytest-xdist \
     # Documentation build dependencies

pyproject.toml

@@ -64,6 +64,7 @@ test = [
     "pytest-xdist",
     "ducc0",
     "nifty8[re]",
+    "nifty8[util]",
 ]
 all = ["nifty8[re,native,parallel,doc,util,test]"]
 

test/test_re/test_refine_healpix.py

@@ -15,6 +15,8 @@ from numpy.testing import assert_allclose, assert_array_equal
 
 import nifty8.re as jft
 
+pytest.importorskip("healpy")
+
 jax.config.update("jax_enable_x64", True)
 
 pmp = pytest.mark.parametrize