BUG: setitem with boolean mask and series as value is broken for Series with EA type (#37676)

Author: phofl

pandas/conftest.py

@@ -1143,6 +1143,26 @@ def any_nullable_int_dtype(request):
     return request.param
 
 
+@pytest.fixture(params=tm.ALL_EA_INT_DTYPES + tm.FLOAT_EA_DTYPES)
+def any_numeric_dtype(request):
+    """
+    Parameterized fixture for any nullable integer dtype and
+    any float ea dtypes.
+
+    * 'UInt8'
+    * 'Int8'
+    * 'UInt16'
+    * 'Int16'
+    * 'UInt32'
+    * 'Int32'
+    * 'UInt64'
+    * 'Int64'
+    * 'Float32'
+    * 'Float64'
+    """
+    return request.param
+
+
 @pytest.fixture(params=tm.SIGNED_EA_INT_DTYPES)
 def any_signed_nullable_int_dtype(request):
     """

pandas/tests/series/indexing/test_setitem.py

@@ -144,6 +144,22 @@ def test_setitem_boolean_td64_values_cast_na(self, value):
         expected = Series([NaT, 1, 2], dtype="timedelta64[ns]")
         tm.assert_series_equal(series, expected)
 
+    def test_setitem_boolean_nullable_int_types(self, any_numeric_dtype):
+        # GH: 26468
+        ser = Series([5, 6, 7, 8], dtype=any_numeric_dtype)
+        ser[ser > 6] = Series(range(4), dtype=any_numeric_dtype)
+        expected = Series([5, 6, 2, 3], dtype=any_numeric_dtype)
+        tm.assert_series_equal(ser, expected)
+
+        ser = Series([5, 6, 7, 8], dtype=any_numeric_dtype)
+        ser.loc[ser > 6] = Series(range(4), dtype=any_numeric_dtype)
+        tm.assert_series_equal(ser, expected)
+
+        ser = Series([5, 6, 7, 8], dtype=any_numeric_dtype)
+        loc_ser = Series(range(4), dtype=any_numeric_dtype)
+        ser.loc[ser > 6] = loc_ser.loc[loc_ser > 1]
+        tm.assert_series_equal(ser, expected)
+
 
 class TestSetitemViewCopySemantics:
     def test_setitem_invalidates_datetime_index_freq(self):