Add test and code cleanup

- Fix `_get_bounds_ensure_dtype` to determine `bounds` with axis that has `standard_name` attr (in addition to `axis` attr check)
- Remove unused `dst_lat_bnds` and `dst_lon_bnds` args for `_build_dataset()`
- Add unit test to cover `ValueError` in `regrid2.py` `_build_dataset()`

tests/test_regrid.py

@@ -517,6 +517,18 @@ def test_unknown_variable(self):
         with pytest.raises(KeyError):
             regridder.horizontal("unknown", self.coarse_2d_ds)
 
+    def test_raises_error_if_axis_name_for_dim_cannot_be_determined(self):
+        ds = self.coarse_2d_ds.copy()
+        ds["lat"].attrs["standard_name"] = "latitude"
+        ds["lat"].attrs.pop("axis")
+
+        regridder = regrid2.Regrid2Regridder(ds, self.fine_2d_ds)
+
+        with pytest.raises(
+            ValueError, match="Could not determine axis name for dimension"
+        ):
+            regridder.horizontal("ts", ds)
+
     @pytest.mark.filterwarnings("ignore:.*invalid value.*true_divide.*:RuntimeWarning")
     def test_regrid_input_mask(self):
         regridder = regrid2.Regrid2Regridder(self.coarse_2d_ds, self.fine_2d_ds)

xcdat/regridder/regrid2.py

@@ -3,7 +3,7 @@
 import numpy as np
 import xarray as xr
 
-from xcdat.axis import get_dim_keys
+from xcdat.axis import CF_ATTR_MAP, get_dim_keys
 from xcdat.regridder.base import BaseRegridder, _preserve_bounds
 
 
@@ -105,8 +105,6 @@ def horizontal(self, data_var: str, ds: xr.Dataset) -> xr.Dataset:
             ds,
             data_var,
             output_data,
-            dst_lat_bnds,
-            dst_lon_bnds,
             self._input_grid,
             self._output_grid,
         )
@@ -228,8 +226,6 @@ def _build_dataset(
     ds: xr.Dataset,
     data_var: str,
     output_data: np.ndarray,
-    dst_lat_bnds,
-    dst_lon_bnds,
     input_grid: xr.Dataset,
     output_grid: xr.Dataset,
 ) -> xr.Dataset:
@@ -242,11 +238,13 @@ def _build_dataset(
         dim = str(dim)
 
         try:
-            axis_name = [x for x, y in ds.cf.axes.items() if dim in y][0]
-        except Exception:
+            axis_name = [
+                cf_axis for cf_axis, dims in ds.cf.axes.items() if dim in dims
+            ][0]
+        except IndexError as e:
             raise ValueError(
                 f"Could not determine axis name for dimension {dim}"
-            ) from None
+            ) from e
 
         if axis_name in ["X", "Y"]:
             output_coords[dim] = output_grid.cf[axis_name]
@@ -566,12 +564,20 @@ def _get_dimension(input_data_var, cf_axis_name):
 
 
 def _get_bounds_ensure_dtype(ds, axis):
-    try:
-        name = ds.cf.bounds[axis][0]
-    except (KeyError, IndexError) as e:
-        raise RuntimeError(f"Could not determine {axis!r} bounds") from e
-    else:
-        bounds = ds[name]
+    cf_keys = CF_ATTR_MAP[axis].values()
+
+    bounds = None
+
+    for key in cf_keys:
+        try:
+            name = ds.cf.bounds[key][0]
+        except (KeyError, IndexError):
+            pass
+        else:
+            bounds = ds[name]
+
+    if bounds is None:
+        raise RuntimeError(f"Could not determine {axis!r} bounds")
 
     if bounds.dtype != np.float32:
         bounds = bounds.astype(np.float32)