diff --git a/tests/test_generation.py b/tests/test_generation.py
index d039115e9..6253bfa4f 100644
--- a/tests/test_generation.py
+++ b/tests/test_generation.py
@@ -78,10 +78,28 @@ def _compare_attributes(obj1, obj2, exclude=None):
 
         if isinstance(val1, np.ndarray):
             assert np.allclose(val1, val2)
+        elif attr == "prim_interstitial_coords":
+            _compare_prim_interstitial_coords(val1, val2)
+        elif attr == "defects" and any(len(i.defect_structure) == 0 for i in val1["vacancies"]):
+            continue  # StructureMatcher comparison breaks for empty structures, which we can have with
+            # our 1-atom primitive Cu input
         else:
             assert val1 == val2
 
 
+def _compare_prim_interstitial_coords(result, expected):  # check attribute set
+    if result is None:
+        assert expected is None
+        return
+
+    assert len(result) == len(expected), "Lengths do not match"
+
+    for (r_coord, r_num, r_list), (e_coord, e_num, e_list) in zip(result, expected):
+        assert np.array_equal(r_coord, e_coord), "Coordinates do not match"
+        assert r_num == e_num, "Number of coordinates do not match"
+        assert all(np.array_equal(r, e) for r, e in zip(r_list, e_list)), "List of arrays do not match"
+
+
 class DefectsGeneratorTest(unittest.TestCase):
     def setUp(self):
         # don't run heavy tests on GH Actions, these are run locally (too slow without multiprocessing etc)
@@ -1453,18 +1471,7 @@ def test_interstitial_coords(self):
             (np.array([0.75, 0.75, 0.75]), 1, [np.array([0.75, 0.75, 0.75])]),
             (np.array([0.5, 0.5, 0.5]), 1, [np.array([0.5, 0.5, 0.5])]),
         ]
-
-        def _test_prim_interstitial_coords(result, expected):  # check attribute set
-            assert len(result) == len(expected), "Lengths do not match"
-
-            for (r_coord, r_num, r_list), (e_coord, e_num, e_list) in zip(result, expected):
-                assert np.array_equal(r_coord, e_coord), "Coordinates do not match"
-                assert r_num == e_num, "Number of coordinates do not match"
-                assert all(
-                    np.array_equal(r, e) for r, e in zip(r_list, e_list)
-                ), "List of arrays do not match"
-
-        _test_prim_interstitial_coords(CdTe_defect_gen.prim_interstitial_coords, expected)
+        _compare_prim_interstitial_coords(CdTe_defect_gen.prim_interstitial_coords, expected)
 
         # defect_gen_check changes defect_entries ordering, so save to json first:
         self._save_defect_gen_jsons(CdTe_defect_gen)
@@ -1475,7 +1482,7 @@ def _test_prim_interstitial_coords(result, expected):  # check attribute set
             self.prim_cdte, interstitial_coords=[[0.5, 0.5, 0.5]], extrinsic={"Te": ["Se", "S"]}
         )
         assert CdTe_defect_gen.interstitial_coords == [[0.5, 0.5, 0.5]]  # check attribute set
-        _test_prim_interstitial_coords(
+        _compare_prim_interstitial_coords(
             CdTe_defect_gen.prim_interstitial_coords,
             [(np.array([0.5, 0.5, 0.5]), 1, [np.array([0.5, 0.5, 0.5])])],  # check attribute set
         )
@@ -1516,7 +1523,7 @@ def _test_prim_interstitial_coords(result, expected):  # check attribute set
         self._load_and_test_defect_gen_jsons(ytos_defect_gen)
 
         assert ytos_defect_gen.interstitial_coords == ytos_interstitial_coords  # check attribute set
-        _test_prim_interstitial_coords(
+        _compare_prim_interstitial_coords(
             ytos_defect_gen.prim_interstitial_coords,
             [
                 (
@@ -1563,7 +1570,7 @@ def _test_prim_interstitial_coords(result, expected):  # check attribute set
         assert (
             CdTe_defect_gen.interstitial_coords == CdTe_supercell_interstitial_coords
         )  # check attribute set
-        _test_prim_interstitial_coords(
+        _compare_prim_interstitial_coords(
             CdTe_defect_gen.prim_interstitial_coords,
             [
                 (