From f106360252f1223b0b521972eb247f447ef3add6 Mon Sep 17 00:00:00 2001
From: "Sadie L. Bartholomew" <sadie.bartholomew@ncas.ac.uk>
Date: Tue, 14 Apr 2026 16:06:26 +0100
Subject: [PATCH 01/10] Add missing ESMPy module availability test skips

---
 cf/test/test_RegridOperator.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/cf/test/test_RegridOperator.py b/cf/test/test_RegridOperator.py
index 28cf79f215..7367ab1e25 100644
--- a/cf/test/test_RegridOperator.py
+++ b/cf/test/test_RegridOperator.py
@@ -55,6 +55,7 @@ def test_RegridOperator_attributes(self):
     def test_RegridOperator_copy(self):
         self.assertIsInstance(self.r.copy(), self.r.__class__)
 
+    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_RegridOperator_equal_weights(self):
         r0 = self.r
         r1 = r0.copy()
@@ -62,6 +63,7 @@ def test_RegridOperator_equal_weights(self):
         r1.weights.data += 0.1
         self.assertFalse(r0.equal_weights(r1))
 
+    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_RegridOperator_equal_dst_mask(self):
         r0 = self.r.copy()
         r1 = r0.copy()

From 2e885f2f037dd52d13f01d5c97a26f44be521a6e Mon Sep 17 00:00:00 2001
From: "Sadie L. Bartholomew" <sadie.bartholomew@ncas.ac.uk>
Date: Tue, 14 Apr 2026 16:25:06 +0100
Subject: [PATCH 02/10] Add test_Domain healpix module availability test
 skipping

---
 cf/test/test_Domain.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/cf/test/test_Domain.py b/cf/test/test_Domain.py
index 15e492b140..2e760fed3c 100644
--- a/cf/test/test_Domain.py
+++ b/cf/test/test_Domain.py
@@ -1,11 +1,18 @@
 import datetime
 import re
 import unittest
+from importlib.util import find_spec
 
 import numpy as np
 
 import cf
 
+healpix_available = False
+# Note: here only need healpix for cf under-the-hood code, not in test
+# directly, so no need to actually import healpix, just test it is there.
+if find_spec("healpix"):
+    healpix_available = True
+
 
 class DomainTest(unittest.TestCase):
     d = cf.example_field(1).domain
@@ -494,6 +501,7 @@ def test_Domain_cyclic_iscyclic(self):
         d2.cyclic("X", iscyclic=False)
         self.assertTrue(d2.iscyclic("X"))
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_Domain_create_healpix(self):
         """Test Domain.create_healpix."""
         d = cf.Domain.create_healpix(0)

From 44357b8611c5a3bbbd16042840c68519c4648e20 Mon Sep 17 00:00:00 2001
From: "Sadie L. Bartholomew" <sadie.bartholomew@ncas.ac.uk>
Date: Tue, 14 Apr 2026 16:35:55 +0100
Subject: [PATCH 03/10] Add test_weights healpix module availability test
 skipping

---
 cf/test/test_weights.py | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/cf/test/test_weights.py b/cf/test/test_weights.py
index 5043a6b796..90e4ebd70f 100644
--- a/cf/test/test_weights.py
+++ b/cf/test/test_weights.py
@@ -1,10 +1,17 @@
 import datetime
 import unittest
+from importlib.util import find_spec
 
 import numpy as np
 
 import cf
 
+healpix_available = False
+# Note: here only need healpix for cf under-the-hood code, not in test
+# directly, so no need to actually import healpix, just test it is there.
+if find_spec("healpix"):
+    healpix_available = True
+
 # A radius greater than 1. Used since weights based on the unit
 # sphere and non-spheres are tested separately.
 r = 2
@@ -152,6 +159,7 @@ def test_weights_polygon_area_geometry(self):
         self.assertTrue((w.array == correct_weights).all())
         self.assertEqual(w.Units, cf.Units("m2"))
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_weights_polygon_area_ugrid(self):
         f = cf.example_field(8)
         f = f[..., [0, 2]]
@@ -345,6 +353,7 @@ def test_weights_exceptions(self):
         ):
             f.weights("area")
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_weights_healpix(self):
         """Test HEALPix weights."""
         # HEALPix grid with Multi-Order Coverage (a combination of

From b39b4023a9a44cecffe2fbccbeb4bf38837f8773 Mon Sep 17 00:00:00 2001
From: "Sadie L. Bartholomew" <sadie.bartholomew@ncas.ac.uk>
Date: Tue, 14 Apr 2026 16:50:25 +0100
Subject: [PATCH 04/10] Add healpix module availability test skips to
 field-related tests

---
 cf/test/test_Field.py    | 12 ++++++++++++
 cf/test/test_collapse.py |  8 ++++++++
 2 files changed, 20 insertions(+)

diff --git a/cf/test/test_Field.py b/cf/test/test_Field.py
index 8b60ba5b06..d399f3e18f 100644
--- a/cf/test/test_Field.py
+++ b/cf/test/test_Field.py
@@ -16,6 +16,12 @@
 
 import cf
 
+healpix_available = False
+# Note: here only need healpix for cf under-the-hood code, not in test
+# directly, so no need to actually import healpix, just test it is there.
+if find_spec("healpix"):
+    healpix_available = True
+
 n_tmpfiles = 1
 tmpfiles = [
     tempfile.mkstemp("_test_Field.nc", dir=os.getcwd())[1]
@@ -3137,6 +3143,7 @@ def test_Field_to_units(self):
         with self.assertRaises(ValueError):
             g.to_units("degC")
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_Field_healpix_change_indexing_scheme(self):
         """Test Field.healpix_change_indexing_scheme."""
         # HEALPix field
@@ -3236,6 +3243,7 @@ def test_Field_healpix_change_indexing_scheme(self):
         with self.assertRaises(ValueError):
             self.f0.healpix_change_indexing_scheme("ring")
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_Field_healpix_to_ugrid(self):
         """Test Field.healpix_to_ugrid."""
         # HEALPix field
@@ -3276,6 +3284,7 @@ def test_Field_healpix_to_ugrid(self):
         with self.assertRaises(ValueError):
             self.f0.healpix_to_ugrid()
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_Field_create_latlon_coordinates(self):
         """Test Field.create_latlon_coordinates."""
         # ------------------------------------------------------------
@@ -3334,6 +3343,7 @@ def test_Field_create_latlon_coordinates(self):
             self.assertTrue(mc[:16].equals(l2.auxiliary_coordinate(c)[:16]))
             self.assertTrue(mc[16:].equals(l1.auxiliary_coordinate(c)[4:]))
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_Field_healpix_subspace(self):
         """Test Field.subspace for HEALPix grids"""
         f = self.f12
@@ -3369,6 +3379,7 @@ def test_Field_healpix_subspace(self):
             np.array_equal(g.coordinate("healpix_index"), [13, 12])
         )
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_Field_healpix_decrease_refinement_level(self):
         """Test Field.healpix_decrease_refinement_level."""
         f = self.f12
@@ -3469,6 +3480,7 @@ def my_mean(a, axis=None):
         with self.assertRaises(ValueError):
             self.f0.healpix_decrease_refinement_level(0, "mean")
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_Field_healpix_increase_refinement_level(self):
         """Test Field.healpix_increase_refinement_level."""
         f = self.f12
diff --git a/cf/test/test_collapse.py b/cf/test/test_collapse.py
index 2dde8679c5..ce7fc5bd52 100644
--- a/cf/test/test_collapse.py
+++ b/cf/test/test_collapse.py
@@ -4,6 +4,7 @@
 import os
 import tempfile
 import unittest
+from importlib.util import find_spec
 
 import numpy as np
 
@@ -11,6 +12,12 @@
 
 import cf
 
+healpix_available = False
+# Note: here only need healpix for cf under-the-hood code, not in test
+# directly, so no need to actually import healpix, just test it is there.
+if find_spec("healpix"):
+    healpix_available = True
+
 n_tmpfiles = 1
 tmpfiles = [
     tempfile.mkstemp("_test_collapse.nc", dir=os.getcwd())[1]
@@ -825,6 +832,7 @@ def test_Field_collapse_ugrid(self):
         # Check the collpsed fields writes
         cf.write(f, tmpfile)
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_Field_collapse_HEALPix(self):
         """Test HEALPix collapses."""
         f0 = cf.example_field(12)

From d77c4243ebdbbb624e6551baf160efaf2884501b Mon Sep 17 00:00:00 2001
From: "Sadie L. Bartholomew" <sadie.bartholomew@ncas.ac.uk>
Date: Tue, 14 Apr 2026 17:27:17 +0100
Subject: [PATCH 05/10] Add module availability module-level test skip for
 test_HEALPix_utils

---
 .flake8                       |  3 ++
 cf/test/test_HEALPix_utils.py | 52 +++++++++++++++++++++++------------
 2 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/.flake8 b/.flake8
index 75d2e1a211..0ebbb3f85c 100644
--- a/.flake8
+++ b/.flake8
@@ -30,3 +30,6 @@ per-file-ignores =
     # https://stackoverflow.com/questions/59167405/)
     __init__.py: F401
     */__init__.py: F401
+    # Whole-module test skip means exit before reach undefined vars where need
+    # given (healpix) module for defining those. Is cleanest way but needs:
+    cf/test/test_HEALPix_utils.py: F821
diff --git a/cf/test/test_HEALPix_utils.py b/cf/test/test_HEALPix_utils.py
index bec272cda6..514b9f7014 100644
--- a/cf/test/test_HEALPix_utils.py
+++ b/cf/test/test_HEALPix_utils.py
@@ -1,33 +1,49 @@
 import datetime
 import unittest
 
-import healpix
 import numpy as np
 
 import cf
 
-# Create matching lists of selected nested, ring, nuniq and zuniq
-# indices for every refinement level.
-indices = [
-    (r, i, healpix.nest2ring(healpix.order2nside(r), i))
-    for r in range(30)
-    for i in (0, 7, (12 * 4**r) - 1)
-]
-refinement_levels, nested_indices, ring_indices = map(list, zip(*indices))
-
-nuniq_indices = [
-    i + 4 ** (1 + r) for r, i in zip(refinement_levels, nested_indices)
-]
-
-zuniq_indices = [
-    (2 * i + 1) * 4 ** (29 - r)
-    for r, i in zip(refinement_levels, nested_indices)
-]
+healpix_imported = True
+try:
+    import healpix  # noqa: F401
+except ImportError:
+    healpix_imported = False
 
 
 class DataTest(unittest.TestCase):
     """Unit tests for HEALPix utilities."""
 
+    def setUp(self):
+        """Preparations called immediately before each test method."""
+        # Skip all if healpix module not available!
+        if not healpix_imported:
+            self.skipTest(
+                "Test module requires 'healpix' package. Install it to run all."
+            )
+        else:
+            # Create matching lists of selected nested, ring, nuniq and zuniq
+            # indices for every refinement level.
+            indices = [
+                (r, i, healpix.nest2ring(healpix.order2nside(r), i))
+                for r in range(30)
+                for i in (0, 7, (12 * 4**r) - 1)
+            ]
+            refinement_levels, nested_indices, ring_indices = map(
+                list, zip(*indices)
+            )
+
+            nuniq_indices = [  # noqa: F841
+                i + 4 ** (1 + r)
+                for r, i in zip(refinement_levels, nested_indices)
+            ]
+
+            zuniq_indices = [  # noqa: F841
+                (2 * i + 1) * 4 ** (29 - r)
+                for r, i in zip(refinement_levels, nested_indices)
+            ]
+
     def test_HEALPix_uniq2zuniq(self):
         """Test _uniq2zuniq"""
         from cf.data.dask_utils_healpix import _uniq2zuniq

From cad2ba47e5ace86e486e202eb20fd757d29a16cd Mon Sep 17 00:00:00 2001
From: "Sadie L. Bartholomew" <sadie.bartholomew@ncas.ac.uk>
Date: Wed, 15 Apr 2026 16:28:34 +0100
Subject: [PATCH 06/10] Add subtle esmpy availability test_regrid skip to avoid
 false positive

---
 cf/test/test_regrid.py | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/cf/test/test_regrid.py b/cf/test/test_regrid.py
index f5d4675ca4..3d6bf98e04 100644
--- a/cf/test/test_regrid.py
+++ b/cf/test/test_regrid.py
@@ -11,6 +11,12 @@
 
 import cf
 
+esmpy_imported = True
+try:
+    import esmpy  # noqa: F401
+except ImportError:
+    esmpy_imported = False
+
 n_tmpfiles = 1
 tmpfiles = [
     tempfile.mkstemp("_test_regrid.nc", dir=os.getcwd())[1]
@@ -30,14 +36,6 @@ def _remove_tmpfiles():
 
 atexit.register(_remove_tmpfiles)
 
-
-esmpy_imported = True
-try:
-    import esmpy  # noqa: F401
-except ImportError:
-    esmpy_imported = False
-
-
 all_methods = (
     "linear",
     "conservative",
@@ -405,6 +403,7 @@ def test_Field_regridc_2d_coords(self):
         d1 = src.regridc(r)
         self.assertTrue(d1.data.equals(d0.data, atol=atol, rtol=rtol))
 
+    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regrids_bad_dst(self):
         """Disallowed destination grid types raise an exception."""
         self.assertFalse(cf.regrid_logging())

From 45dbe80d12509370003f2436535deb43c94aa96e Mon Sep 17 00:00:00 2001
From: "Sadie L. Bartholomew" <sadie.bartholomew@ncas.ac.uk>
Date: Wed, 15 Apr 2026 16:37:53 +0100
Subject: [PATCH 07/10] Convert test_regrid esmpy availability test skips to
 module-level

---
 .flake8                |  5 +++--
 cf/test/test_regrid.py | 43 +++++++++++++++++++-----------------------
 2 files changed, 22 insertions(+), 26 deletions(-)

diff --git a/.flake8 b/.flake8
index 0ebbb3f85c..e1881075ff 100644
--- a/.flake8
+++ b/.flake8
@@ -30,6 +30,7 @@ per-file-ignores =
     # https://stackoverflow.com/questions/59167405/)
     __init__.py: F401
     */__init__.py: F401
-    # Whole-module test skip means exit before reach undefined vars where need
-    # given (healpix) module for defining those. Is cleanest way but needs:
+    # Whole-module test skips (via setUp method) for these cases means exit
+    # before reach undefined vars where need given module for defining those.
+    # This is the cleanest way but sets off F821 so skip those:
     cf/test/test_HEALPix_utils.py: F821
diff --git a/cf/test/test_regrid.py b/cf/test/test_regrid.py
index 3d6bf98e04..b523f25191 100644
--- a/cf/test/test_regrid.py
+++ b/cf/test/test_regrid.py
@@ -138,19 +138,27 @@ def esmpy_regrid_Nd(coord_sys, method, src, dst, **kwargs):
 
 
 class RegridTest(unittest.TestCase):
-    # Get the test source and destination fields
-    filename = os.path.join(
-        os.path.dirname(os.path.abspath(__file__)), "regrid.nc"
-    )
-    dst_src = cf.read(filename)
-    dst = dst_src[0]
-    src = dst_src[1]
 
-    filename_xyz = os.path.join(
-        os.path.dirname(os.path.abspath(__file__)), "regrid_xyz.nc"
-    )
+    def setUp(self):
+        """Preparations called immediately before each test method."""
+        # Skip all if healpix module not available!
+        if not esmpy_imported:
+            self.skipTest(
+                "Test module requires 'esmpy' package. Install it to run all."
+            )
+        else:
+            # Get the test source and destination fields
+            filename = os.path.join(
+                os.path.dirname(os.path.abspath(__file__)), "regrid.nc"
+            )
+            dst_src = cf.read(filename)
+            dst = dst_src[0]  # noqa: F841
+            src = dst_src[1]  # noqa: F841
+
+            filename_xyz = os.path.join(  # noqa: F841
+                os.path.dirname(os.path.abspath(__file__)), "regrid_xyz.nc"
+            )
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regrid_2d_field(self):
         """2-d regridding with Field destination grid."""
         self.assertFalse(cf.regrid_logging())
@@ -302,7 +310,6 @@ def test_Field_regrid_2d_field(self):
             with self.assertRaises(ValueError):
                 src.regrids(dst, method=method).array
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regrids_coords(self):
         """Spherical regridding with coords destination grid."""
         self.assertFalse(cf.regrid_logging())
@@ -372,7 +379,6 @@ def test_Field_regrids_coords(self):
         d1 = src.regrids(r)
         self.assertTrue(d1.data.equals(d0.data, atol=atol, rtol=rtol))
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regridc_2d_coords(self):
         """2-d Cartesian regridding with coords destination grid."""
         self.assertFalse(cf.regrid_logging())
@@ -403,7 +409,6 @@ def test_Field_regridc_2d_coords(self):
         d1 = src.regridc(r)
         self.assertTrue(d1.data.equals(d0.data, atol=atol, rtol=rtol))
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regrids_bad_dst(self):
         """Disallowed destination grid types raise an exception."""
         self.assertFalse(cf.regrid_logging())
@@ -417,7 +422,6 @@ def test_Field_regrids_bad_dst(self):
         with self.assertRaises(ValueError):
             self.src.regrids("foobar", method="conservative")
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regrids_domain(self):
         """Spherical regridding with Domain destination grid."""
         self.assertFalse(cf.regrid_logging())
@@ -441,7 +445,6 @@ def test_Field_regrids_domain(self):
         d1 = src.regrids(r)
         self.assertTrue(d1.equals(d0, atol=atol, rtol=rtol))
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regridc_domain(self):
         """Spherical regridding with Domain destination grid."""
         self.assertFalse(cf.regrid_logging())
@@ -467,7 +470,6 @@ def test_Field_regridc_domain(self):
         d1 = src.regridc(r)
         self.assertTrue(d1.equals(d0, atol=atol, rtol=rtol))
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regrids_field_operator(self):
         """Spherical regridding with operator destination grid."""
         self.assertFalse(cf.regrid_logging())
@@ -505,7 +507,6 @@ def test_Field_regrids_field_operator(self):
         with self.assertRaises(ValueError):
             dst.regrids(r)
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regrids_non_coordinates(self):
         """Check setting of non-coordinate metadata."""
         self.assertFalse(cf.regrid_logging())
@@ -554,7 +555,6 @@ def test_Field_regrids_non_coordinates(self):
         # Cell measures
         self.assertFalse(d1.cell_measures())
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regridc_3d_field(self):
         """3-d Cartesian regridding with Field destination grid."""
         self.assertFalse(cf.regrid_logging())
@@ -658,7 +658,6 @@ def test_Field_regridc_3d_field(self):
             with self.assertRaises(ValueError):
                 src.regridc(dst, method=method, axes=axes)
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regridc_1d_field(self):
         """1-d Cartesian regridding with Field destination grid."""
         self.assertFalse(cf.regrid_logging())
@@ -749,7 +748,6 @@ def test_Field_regridc_1d_field(self):
             with self.assertRaises(ValueError):
                 src.regridc(dst, method=method, axes=axes)
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regridc_1d_coordinates_z(self):
         """1-d Z Cartesian regridding with coordinates destination grid."""
         self.assertFalse(cf.regrid_logging())
@@ -762,7 +760,6 @@ def test_Field_regridc_1d_coordinates_z(self):
         z = d.dimension_coordinate("Z")
         self.assertTrue(z.data.equals(dst.data))
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regrid_chunks(self):
         """Regridding of chunked axes"""
         self.assertFalse(cf.regrid_logging())
@@ -779,7 +776,6 @@ def test_Field_regrid_chunks(self):
         d0 = src.regrids(dst, method="linear")
         self.assertEqual(d0.data.numblocks, (1, 1, 1))
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_Field_regrid_weights_file(self):
         """Regridding creation/use of weights file"""
         self.assertFalse(cf.regrid_logging())
@@ -815,7 +811,6 @@ def test_Field_regrid_weights_file(self):
                 src.regrids(r1, method="linear", weights_file=tmpfile)
             )
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_return_esmpy_regrid_operator(self):
         """esmpy regrid operator returns esmpy.Regrid in regrids and regridc"""
         self.assertFalse(cf.regrid_logging())

From 7567ac761acd6ebad14f5aee8255c08a1cc738c9 Mon Sep 17 00:00:00 2001
From: "Sadie L. Bartholomew" <sadie.bartholomew@ncas.ac.uk>
Date: Wed, 15 Apr 2026 16:59:25 +0100
Subject: [PATCH 08/10] Add last required healpix availability skip from full
 test suite run

---
 cf/test/test_functions.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/cf/test/test_functions.py b/cf/test/test_functions.py
index 98d186d02a..eb1c984d44 100644
--- a/cf/test/test_functions.py
+++ b/cf/test/test_functions.py
@@ -4,6 +4,7 @@
 import platform
 import sys
 import unittest
+from importlib.util import find_spec
 
 import dask.array as da
 import numpy as np
@@ -12,6 +13,12 @@
 
 import cf
 
+healpix_available = False
+# Note: here only need healpix for cf under-the-hood code, not in test
+# directly, so no need to actually import healpix, just test it is there.
+if find_spec("healpix"):
+    healpix_available = True
+
 
 class functionTest(unittest.TestCase):
     def setUp(self):
@@ -487,6 +494,7 @@ def test_normalize_slice(self):
             with self.assertRaises(IndexError):
                 cf.normalize_slice(index, 8, cyclic=True)
 
+    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
     def test_locate(self):
         """Test cf.locate"""
         # HEALPix

From f674572880d271e8e49b7c57980f47586a0ee16e Mon Sep 17 00:00:00 2001
From: "Sadie L. Bartholomew" <sadie.bartholomew@ncas.ac.uk>
Date: Wed, 15 Apr 2026 17:12:21 +0100
Subject: [PATCH 09/10] Tidy test skip on lone methods to avoid use of flag

---
 .flake8                   |  2 +-
 cf/test/test_Domain.py    | 10 +++-------
 cf/test/test_collapse.py  | 10 +++-------
 cf/test/test_functions.py | 10 +++-------
 4 files changed, 10 insertions(+), 22 deletions(-)

diff --git a/.flake8 b/.flake8
index e1881075ff..fc7bb54da2 100644
--- a/.flake8
+++ b/.flake8
@@ -32,5 +32,5 @@ per-file-ignores =
     */__init__.py: F401
     # Whole-module test skips (via setUp method) for these cases means exit
     # before reach undefined vars where need given module for defining those.
-    # This is the cleanest way but sets off F821 so skip those:
+    # This is the cleanest way but sets off F821 code en-masse so ignore that.
     cf/test/test_HEALPix_utils.py: F821
diff --git a/cf/test/test_Domain.py b/cf/test/test_Domain.py
index 2e760fed3c..59c69c0f22 100644
--- a/cf/test/test_Domain.py
+++ b/cf/test/test_Domain.py
@@ -7,12 +7,6 @@
 
 import cf
 
-healpix_available = False
-# Note: here only need healpix for cf under-the-hood code, not in test
-# directly, so no need to actually import healpix, just test it is there.
-if find_spec("healpix"):
-    healpix_available = True
-
 
 class DomainTest(unittest.TestCase):
     d = cf.example_field(1).domain
@@ -501,7 +495,9 @@ def test_Domain_cyclic_iscyclic(self):
         d2.cyclic("X", iscyclic=False)
         self.assertTrue(d2.iscyclic("X"))
 
-    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
+    # Note: here only need healpix for cf under-the-hood code, not in test
+    # directly, so no need to actually import healpix, just test it is there.
+    @unittest.skipUnless(find_spec("healpix"), "Requires 'healpix' package.")
     def test_Domain_create_healpix(self):
         """Test Domain.create_healpix."""
         d = cf.Domain.create_healpix(0)
diff --git a/cf/test/test_collapse.py b/cf/test/test_collapse.py
index ce7fc5bd52..b3f73f4524 100644
--- a/cf/test/test_collapse.py
+++ b/cf/test/test_collapse.py
@@ -12,12 +12,6 @@
 
 import cf
 
-healpix_available = False
-# Note: here only need healpix for cf under-the-hood code, not in test
-# directly, so no need to actually import healpix, just test it is there.
-if find_spec("healpix"):
-    healpix_available = True
-
 n_tmpfiles = 1
 tmpfiles = [
     tempfile.mkstemp("_test_collapse.nc", dir=os.getcwd())[1]
@@ -832,7 +826,9 @@ def test_Field_collapse_ugrid(self):
         # Check the collpsed fields writes
         cf.write(f, tmpfile)
 
-    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
+    # Note: here only need healpix for cf under-the-hood code, not in test
+    # directly, so no need to actually import healpix, just test it is there.
+    @unittest.skipUnless(find_spec("healpix"), "Requires 'healpix' package.")
     def test_Field_collapse_HEALPix(self):
         """Test HEALPix collapses."""
         f0 = cf.example_field(12)
diff --git a/cf/test/test_functions.py b/cf/test/test_functions.py
index eb1c984d44..b686a98b40 100644
--- a/cf/test/test_functions.py
+++ b/cf/test/test_functions.py
@@ -13,12 +13,6 @@
 
 import cf
 
-healpix_available = False
-# Note: here only need healpix for cf under-the-hood code, not in test
-# directly, so no need to actually import healpix, just test it is there.
-if find_spec("healpix"):
-    healpix_available = True
-
 
 class functionTest(unittest.TestCase):
     def setUp(self):
@@ -494,7 +488,9 @@ def test_normalize_slice(self):
             with self.assertRaises(IndexError):
                 cf.normalize_slice(index, 8, cyclic=True)
 
-    @unittest.skipUnless(healpix_available, "Requires 'healpix' package.")
+    # Note: here only need healpix for cf under-the-hood code, not in test
+    # directly, so no need to actually import healpix, just test it is there.
+    @unittest.skipUnless(find_spec("healpix"), "Requires 'healpix' package.")
     def test_locate(self):
         """Test cf.locate"""
         # HEALPix

From 2088b7e9851bd6abd6ff4cb1d2f0b1eeef1c744f Mon Sep 17 00:00:00 2001
From: "Sadie L. Bartholomew" <sadie.bartholomew@ncas.ac.uk>
Date: Wed, 15 Apr 2026 17:14:39 +0100
Subject: [PATCH 10/10] Convert test skipping to module-level for
 test_RegridOperator

---
 cf/test/test_RegridOperator.py | 16 +++++++++-------
 cf/test/test_regrid.py         |  2 +-
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/cf/test/test_RegridOperator.py b/cf/test/test_RegridOperator.py
index 7367ab1e25..0f062300ce 100644
--- a/cf/test/test_RegridOperator.py
+++ b/cf/test/test_RegridOperator.py
@@ -19,11 +19,16 @@
 class RegridOperatorTest(unittest.TestCase):
 
     def setUp(self):
-        src = cf.example_field(0)
-        dst = cf.example_field(1)
-        self.r = src.regrids(dst, "linear", return_operator=True)
+        # Skip all if espmy module not available!
+        if not esmpy_imported:
+            self.skipTest(
+                "Test module requires 'esmpy' package. Install it to run all."
+            )
+        else:
+            src = cf.example_field(0)
+            dst = cf.example_field(1)
+            self.r = src.regrids(dst, "linear", return_operator=True)
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_RegridOperator_attributes(self):
         self.assertEqual(self.r.coord_sys, "spherical")
         self.assertEqual(self.r.method, "linear")
@@ -51,11 +56,9 @@ def test_RegridOperator_attributes(self):
         self.assertIsNone(self.r.dst_z)
         self.assertFalse(self.r.ln_z)
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_RegridOperator_copy(self):
         self.assertIsInstance(self.r.copy(), self.r.__class__)
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_RegridOperator_equal_weights(self):
         r0 = self.r
         r1 = r0.copy()
@@ -63,7 +66,6 @@ def test_RegridOperator_equal_weights(self):
         r1.weights.data += 0.1
         self.assertFalse(r0.equal_weights(r1))
 
-    @unittest.skipUnless(esmpy_imported, "Requires esmpy/ESMF package.")
     def test_RegridOperator_equal_dst_mask(self):
         r0 = self.r.copy()
         r1 = r0.copy()
diff --git a/cf/test/test_regrid.py b/cf/test/test_regrid.py
index b523f25191..236d852414 100644
--- a/cf/test/test_regrid.py
+++ b/cf/test/test_regrid.py
@@ -141,7 +141,7 @@ class RegridTest(unittest.TestCase):
 
     def setUp(self):
         """Preparations called immediately before each test method."""
-        # Skip all if healpix module not available!
+        # Skip all if esmpy module not available!
         if not esmpy_imported:
             self.skipTest(
                 "Test module requires 'esmpy' package. Install it to run all."