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Author: Giacomo Ferroni

doc/source/whatsnew/v0.20.0.txt

@@ -362,4 +362,4 @@ Bug Fixes
 
 
 - Bug in ``pd.read_csv()`` for the C engine where ``usecols`` were being indexed incorrectly with ``parse_dates`` (:issue:`14792`)
-- Not boolean Series returned by comparison methods (e.g., ``lt``, ``gt``, ...) against a constant for an empty DataFrame (:issue:`15077`)
+- Incorrect dtyped ``Series`` was returned by comparison methods (e.g., ``lt``, ``gt``, ...) against a constant for an empty ``DataFrame`` (:issue:`15077`)

pandas/tests/frame/test_operators.py

@@ -678,20 +678,14 @@ def test_return_dtypes_bool_op_costant(self):
 
         # not empty DataFrame
         for op in ['eq', 'ne', 'gt', 'lt', 'ge', 'le']:
-            f = getattr(df, op)
-            for col in ['x', 'y']:
-                res = f(const)
-                c = getattr(res, col)
-                self.assertEqual(c.dtypes, bool)
+            result = getattr(df, op)(const).get_dtype_counts()
+            self.assert_series_equal(result, Series([2], ['bool']))
 
         # empty DataFrame
         empty = df.iloc[:0]
         for op in ['eq', 'ne', 'gt', 'lt', 'ge', 'le']:
-            f = getattr(empty, op)
-            for col in ['x', 'y']:
-                res = f(const)
-                c = getattr(res, col)
-                self.assertEqual(c.dtypes, bool)
+            result = getattr(empty, op)(const).get_dtype_counts()
+            self.assert_series_equal(result, Series([2], ['bool']))
 
     def test_dti_tz_convert_to_utc(self):
         base = pd.DatetimeIndex(['2011-01-01', '2011-01-02',

pandas/tests/series/test_operators.py

@@ -1297,15 +1297,16 @@ def test_comparison_flex_alignment_fill(self):
     def test_return_dtypes_bool_op_costant(self):
         # gh15115
         s = pd.Series([1, 3, 2], index=range(3))
+        const = 2
         for op in ['eq', 'ne', 'gt', 'lt', 'ge', 'le']:
-            f = getattr(s, op)
-            self.assertFalse(f(2).dtypes, np.dtype('bool'))
+            result = getattr(s, op)(const).get_dtype_counts()
+            self.assert_series_equal(result, Series([1], ['bool']))
 
         # empty Series
         empty = s.iloc[:0]
         for op in ['eq', 'ne', 'gt', 'lt', 'ge', 'le']:
-            f = getattr(empty, op)
-            self.assertFalse(f(2).dtypes, np.dtype('bool'))
+            result = getattr(empty, op)(const).get_dtype_counts()
+            self.assert_series_equal(result, Series([1], ['bool']))
 
     def test_operators_bitwise(self):
         # GH 9016: support bitwise op for integer types