fixed Series.mask code

Author: randolf-scholz

pandas/core/generic.py

@@ -10472,7 +10472,8 @@ def mask(
         cond = common.apply_if_callable(cond, self)
 
         # see gh-21891
-        if not hasattr(cond, "__invert__"):
+        if not hasattr(cond, "shape"):
+            # not testing __invert__, since `~True` is `-2`.
             cond = np.array(cond)
 
         return self.where(

pandas/tests/series/indexing/test_mask.py

@@ -31,9 +31,11 @@ def test_mask():
     rs2 = s2.mask(cond[:3], -s2)
     tm.assert_series_equal(rs, rs2)
 
+    # test scalar
+    assert s.mask(True).isna().all()
+    tm.assert_series_equal(s.mask(False), s)
+
     msg = "Array conditional must be same shape as self"
-    with pytest.raises(ValueError, match=msg):
-        s.mask(1)
     with pytest.raises(ValueError, match=msg):
         s.mask(cond[:3].values, -s)