add holiday snow indicator tests

Signed-off-by: Trevor James Smith <10819524+Zeitsperre@users.noreply.github.com>

tests/test_snow.py

@@ -2,6 +2,7 @@
 
 import numpy as np
 import pytest
+import xarray as xr
 
 from xclim import land
 from xclim.core import ValidationError
@@ -120,3 +121,61 @@ def test_simple(self, snw_series):
         snw = snw_series(a, start="2001-01-01")
         out = land.snw_max_doy(snw, freq="YS")
         np.testing.assert_array_equal(out, [21, np.nan])
+
+
+class TestHolidaySnowIndicators:
+
+    def test_xmas_days_simple(self, nimbus):
+        ds = xr.open_dataset(
+            nimbus.fetch(
+                "cmip6/snw_day_CanESM5_historical_r1i1p1f1_gn_19910101-20101231.nc"
+            )
+        )
+        snd = land.snw_to_snd(ds.snw)
+
+        out = land.holiday_snow_days(snd)
+
+        assert out.units == "1"
+        assert out.long_name == "Number of holiday days with snow"
+        np.testing.assert_array_equal(
+            out.sum(dim="time"),
+            [
+                [7.0, 5.0, 2.0, 0.0, 0.0],
+                [14.0, 13.0, 9.0, 6.0, 2.0],
+                [18.0, 19.0, 19.0, 18.0, 13.0],
+                [20.0, 20.0, 20.0, 20.0, 20.0],
+                [20.0, 20.0, 20.0, 20.0, 20.0],
+                [20.0, 20.0, 20.0, 20.0, 20.0],
+            ],
+        )
+
+    def test_perfect_xmas_days_simple(self, nimbus):
+        ds_snw = xr.open_dataset(
+            nimbus.fetch(
+                "cmip6/snw_day_CanESM5_historical_r1i1p1f1_gn_19910101-20101231.nc"
+            )
+        )
+        ds_prsn = xr.open_dataset(
+            nimbus.fetch(
+                "cmip6/prsn_day_CanESM5_historical_r1i1p1f1_gn_19910101-20101231.nc"
+            )
+        )
+
+        snd = land.snw_to_snd(ds_snw.snw)
+        prsn = ds_prsn.prsn
+
+        out = land.holiday_snow_and_snowfall_days(snd, prsn)
+
+        assert out.units == "1"
+        assert out.long_name == "Number of holiday days with snow and snowfall"
+        np.testing.assert_array_equal(
+            out.sum(dim="time"),
+            [
+                [0.0, 0.0, 0.0, 0.0, 0.0],
+                [0.0, 0.0, 0.0, 0.0, 0.0],
+                [0.0, 0.0, 0.0, 1.0, 0.0],
+                [1.0, 0.0, 0.0, 0.0, 1.0],
+                [0.0, 0.0, 1.0, 1.0, 1.0],
+                [0.0, 0.0, 0.0, 0.0, 0.0],
+            ],
+        )