add test for layer thickness profile generation

tests/test_grid_generation.py

@@ -1,5 +1,6 @@
 import numpy as np
 import pytest
+from regional_mom6 import dz_hyperbolictan
 from regional_mom6 import angle_between
 from regional_mom6 import latlon_to_cartesian
 from regional_mom6 import quadrilateral_area
@@ -8,6 +9,23 @@
 import xarray as xr
 
 
+@pytest.mark.parametrize(
+    ("nlayers", "ratio", "target_depth"),
+    [
+        (20, 1/3, 1000),
+        (20, 2, 1000),
+        (20, 10, 1000),
+        (20, 2, 3000),
+        (50, 1/3, 1000),
+        (50, 2, 1000),
+        (50, 10, 1000),
+        (50, 2, 3000),
+    ],
+)
+def test_dz_hyperbolictan(nlayers, ratio, target_depth):
+    assert np.isclose(dz_hyperbolictan(nlayers, ratio, target_depth),
+                      np.flip(dz_hyperbolictan(nlayers, 1 / ratio, target_depth))).all()
+
 @pytest.mark.parametrize(
     ("lat", "lon", "true_xyz"),
     [