Block-mapped resample with the help of flox

tests/test_indices.py

@@ -29,6 +29,11 @@
 from xclim.core.options import set_options
 from xclim.core.units import convert_units_to, units
 
+try:
+    import flox
+except ImportError:
+    flox = None
+
 K2C = 273.15
 
 
@@ -1430,7 +1435,9 @@ def test_resampling_order(self, tasmax_series, resample_before_rl, expected):
         a[5:35] = 31
         tx = tasmax_series(a + K2C).chunk()
 
-        with set_options(resample_map_blocks=resample_before_rl):
+        with set_options(
+            resample_map_blocks=(resample_before_rl and (flox is not None))
+        ):
             hsf = xci.hot_spell_frequency(
                 tx, resample_before_rl=resample_before_rl, freq="MS"
             ).load()
@@ -1710,7 +1717,9 @@ def test_resampling_order(self, pr_series, resample_before_rl, expected):
         a = np.zeros(365) + 10
         a[5:35] = 0
         pr = pr_series(a).chunk()
-        with set_options(resample_map_blocks=resample_before_rl):
+        with set_options(
+            resample_map_blocks=(resample_before_rl and (flox is not None))
+        ):
             out = xci.maximum_consecutive_dry_days(
                 pr, freq="ME", resample_before_rl=resample_before_rl
             ).load()