done

lib/python3.11/site-packages/pandas/tests/series/methods/test_nunique.py

@@ -0,0 +1,24 @@
+import numpy as np
+
+from pandas import (
+    Categorical,
+    Series,
+)
+
+
+def test_nunique():
+    # basics.rst doc example
+    series = Series(np.random.default_rng(2).standard_normal(500))
+    series[20:500] = np.nan
+    series[10:20] = 5000
+    result = series.nunique()
+    assert result == 11
+
+
+def test_nunique_categorical():
+    # GH#18051
+    ser = Series(Categorical([]))
+    assert ser.nunique() == 0
+
+    ser = Series(Categorical([np.nan]))
+    assert ser.nunique() == 0