diff --git a/pyphare/pyphare/core/box.py b/pyphare/pyphare/core/box.py
index 15d5e571d..3b5faab6a 100644
--- a/pyphare/pyphare/core/box.py
+++ b/pyphare/pyphare/core/box.py
@@ -185,3 +185,36 @@ def copy(arr, replace):
 
 def amr_to_local(box, ref_box):
     return Box(box.lower - ref_box.lower, box.upper - ref_box.lower)
+
+
+
+def diff_boxes(self, slice1, slice2, box, atol=None):
+    if atol is not None:
+        ignore = np.isclose(slice1, slice2, atol=atol, rtol=0)
+        def _diff(slice0):
+            slice0[ignore] = 0 # set values which are within atol range to 0
+            return slice0
+        diff = np.abs(_diff(slice1.copy()) - _diff(slice2.copy()))
+    else:
+        diff = np.abs(slice1 - slice2)
+
+    boxes = []
+    if box.ndim == 1:
+        x1 = np.where(diff != 0)
+        for x in zip(x1):
+            x = x+box.lower[0]
+            boxes += [Box([x], [x])]
+    elif box.ndim == 2:
+        x1, y1 = np.where(diff != 0)
+        for x, y in zip(x1, y1):
+            x = x+box.lower[0]
+            y = y+box.lower[1]
+            boxes += [Box([x, y], [x, y])]
+    elif box.ndim == 3:
+        x1, y1, z1 = np.where(diff != 0)
+        for x, y, z in zip(x1, y1, z1):
+            x = x+box.lower[0]
+            y = y+box.lower[1]
+            z = y+box.lower[2]
+            boxes += [Box([x, y, z], [x, y, z])]
+    return boxes
diff --git a/pyphare/pyphare/pharesee/geometry.py b/pyphare/pyphare/pharesee/geometry.py
index 1f6a87b4f..d259fa8a6 100644
--- a/pyphare/pyphare/pharesee/geometry.py
+++ b/pyphare/pyphare/pharesee/geometry.py
@@ -298,7 +298,7 @@ def borders_per(box):
 
             if in_sides in shifts: # in_sides might be empty, so no borders
                 for shift in shifts[in_sides]:
-                    patch_copy = patch.copy()
+                    patch_copy = copy(patch)
                     shift_patch(patch_copy, shift)
                     sorted_patches.append(patch_copy)
 
diff --git a/pyphare/pyphare/pharesee/hierarchy.py b/pyphare/pyphare/pharesee/hierarchy.py
index 57cdf9665..cfaf1dcb4 100644
--- a/pyphare/pyphare/pharesee/hierarchy.py
+++ b/pyphare/pyphare/pharesee/hierarchy.py
@@ -208,6 +208,9 @@ def copy(self):
         from copy import deepcopy
         return deepcopy(self)
 
+    def __copy__(self):
+        return self.copy()
+
 
 
 class PatchLevel:
diff --git a/src/amr/data/field/time_interpolate/field_linear_time_interpolate.h b/src/amr/data/field/time_interpolate/field_linear_time_interpolate.h
index 75f5db7b3..93f4d2c6d 100644
--- a/src/amr/data/field/time_interpolate/field_linear_time_interpolate.h
+++ b/src/amr/data/field/time_interpolate/field_linear_time_interpolate.h
@@ -40,7 +40,7 @@ class FieldLinearTimeInterpolate : public SAMRAI::hier::TimeInterpolateOperator
 
 
     void timeInterpolate(SAMRAI::hier::PatchData& destData, SAMRAI::hier::Box const& where,
-                         SAMRAI::hier::BoxOverlap const& /*overlap_*/,
+                         SAMRAI::hier::BoxOverlap const& /*overlap*/,
                          SAMRAI::hier::PatchData const& srcDataOld,
                          SAMRAI::hier::PatchData const& srcDataNew) const override
     {
diff --git a/tests/simulator/test_advance.py b/tests/simulator/test_advance.py
index b3e35885c..0827fb1d3 100644
--- a/tests/simulator/test_advance.py
+++ b/tests/simulator/test_advance.py
@@ -250,7 +250,7 @@ def base_test_overlaped_fields_are_equal(self, datahier, coarsest_time):
                         print("AssertionError", pd1.name, e)
                         if self.rethrow_:
                             raise e
-                        return self._diffBoxes(slice1, slice2, box)
+                        return boxm.diff_boxes(slice1, slice2, box)
 
         return checks
 
@@ -410,6 +410,7 @@ def _test_field_coarsening_via_subcycles(self, dim, interp_order, refinement_box
                                     afterCoarse = np.copy(coarse_pdDataset)
 
                                     # change values that should be updated to make failure obvious
+                                    assert(dim < 3) # update
                                     if dim == 1:
                                         afterCoarse[dataBox.lower[0] : dataBox.upper[0] + 1] = -144123
                                     if dim == 2:
@@ -419,23 +420,7 @@ def _test_field_coarsening_via_subcycles(self, dim, interp_order, refinement_box
                                     coarsen(qty, coarse_pd, fine_pd, coarseBox, fine_pdDataset, afterCoarse)
                                     np.testing.assert_allclose(coarse_pdDataset, afterCoarse, atol=1e-16, rtol=0)
 
-    def _diffBoxes(self, slice1, slice2, box, atol=None):
-        if atol is not None:
-            ignore = np.isclose(slice1, slice2, atol=atol, rtol=0)
-            def _diff(slice0):
-                slice0[ignore] = 0 # set values which are within atol range to 0
-                return slice0
-            diff = np.abs(_diff(slice1.copy()) - _diff(slice2.copy()))
-        else:
-            diff = np.abs(slice1 - slice2)
-        where = np.where(diff != 0)
-        boxes = []
-        x1, y1 = where
-        for x, y in zip(x1, y1):
-            x = x+box.lower[0]
-            y = y+box.lower[1]
-            boxes += [Box([x, y], [x, y])]
-        return boxes
+
 
 
     def base_test_field_level_ghosts_via_subcycles_and_coarser_interpolation(self, L0_datahier, L0L1_datahier, quantities=None):
@@ -463,7 +448,7 @@ def assert_time_in_hier(*ts):
 
         fine_subcycle_times = []
         for fine_subcycle in range(global_vars.sim.level_step_nbr[fine_ilvl] + 1):
-            fine_subcycle_time   = coarsest_time_before + (lvl_steps[fine_ilvl] * fine_subcycle)
+            fine_subcycle_time = coarsest_time_before + (lvl_steps[fine_ilvl] * fine_subcycle)
             assert_time_in_hier(fine_subcycle_time)
             fine_subcycle_times += [fine_subcycle_time]
 
@@ -517,7 +502,7 @@ def assert_time_in_hier(*ts):
                                         print(f"FAIL level ghost subcycle_coarsening qty {qty}", e)
                                         if self.rethrow_:
                                             raise e
-                                        error_boxes += self._diffBoxes(fine_ghostbox_data, refinedInterpGhostBox_data, box, atol=1e-15)
+                                        error_boxes += boxm.diff_boxes(fine_ghostbox_data, refinedInterpGhostBox_data, box, atol=1e-15)
                                     checks += 1
         if len(error_boxes): return error_boxes
         return checks