TST: FIXMES in DataFrame.quantile tests (pandas-dev#44437)

Author: jbrockmendel

pandas/tests/frame/methods/test_quantile.py

@@ -280,9 +280,13 @@ def test_quantile_datetime(self):
         tm.assert_frame_equal(result, expected)
 
         # empty when numeric_only=True
-        # FIXME (gives empty frame in 0.18.1, broken in 0.19.0)
-        # result = df[['a', 'c']].quantile(.5)
-        # result = df[['a', 'c']].quantile([.5])
+        result = df[["a", "c"]].quantile(0.5)
+        expected = Series([], index=[], dtype=np.float64, name=0.5)
+        tm.assert_series_equal(result, expected)
+
+        result = df[["a", "c"]].quantile([0.5])
+        expected = DataFrame(index=[0.5])
+        tm.assert_frame_equal(result, expected)
 
     def test_quantile_invalid(self, datetime_frame):
         msg = "percentiles should all be in the interval \\[0, 1\\]"
@@ -481,7 +485,7 @@ def test_quantile_nat(self):
         )
         tm.assert_frame_equal(res, exp)
 
-    def test_quantile_empty_no_rows(self):
+    def test_quantile_empty_no_rows_floats(self):
 
         # floats
         df = DataFrame(columns=["a", "b"], dtype="float64")
@@ -494,21 +498,43 @@ def test_quantile_empty_no_rows(self):
         exp = DataFrame([[np.nan, np.nan]], columns=["a", "b"], index=[0.5])
         tm.assert_frame_equal(res, exp)
 
-        # FIXME (gives empty frame in 0.18.1, broken in 0.19.0)
-        # res = df.quantile(0.5, axis=1)
-        # res = df.quantile([0.5], axis=1)
+        res = df.quantile(0.5, axis=1)
+        exp = Series([], index=[], dtype="float64", name=0.5)
+        tm.assert_series_equal(res, exp)
+
+        res = df.quantile([0.5], axis=1)
+        exp = DataFrame(columns=[], index=[0.5])
+        tm.assert_frame_equal(res, exp)
 
+    def test_quantile_empty_no_rows_ints(self):
         # ints
         df = DataFrame(columns=["a", "b"], dtype="int64")
 
-        # FIXME (gives empty frame in 0.18.1, broken in 0.19.0)
-        # res = df.quantile(0.5)
+        res = df.quantile(0.5)
+        exp = Series([np.nan, np.nan], index=["a", "b"], name=0.5)
+        tm.assert_series_equal(res, exp)
 
+    def test_quantile_empty_no_rows_dt64(self):
         # datetimes
         df = DataFrame(columns=["a", "b"], dtype="datetime64[ns]")
 
-        # FIXME (gives NaNs instead of NaT in 0.18.1 or 0.19.0)
-        # res = df.quantile(0.5, numeric_only=False)
+        res = df.quantile(0.5, numeric_only=False)
+        exp = Series(
+            [pd.NaT, pd.NaT], index=["a", "b"], dtype="datetime64[ns]", name=0.5
+        )
+        tm.assert_series_equal(res, exp)
+
+        # Mixed dt64/dt64tz
+        df["a"] = df["a"].dt.tz_localize("US/Central")
+        res = df.quantile(0.5, numeric_only=False)
+        exp = exp.astype(object)
+        tm.assert_series_equal(res, exp)
+
+        # both dt64tz
+        df["b"] = df["b"].dt.tz_localize("US/Central")
+        res = df.quantile(0.5, numeric_only=False)
+        exp = exp.astype(df["b"].dtype)
+        tm.assert_series_equal(res, exp)
 
     def test_quantile_empty_no_columns(self):
         # GH#23925 _get_numeric_data may drop all columns