check first and last points' labels are correct (#31659)

Author: MarcoGorelli

pandas/tests/plotting/test_datetimelike.py

@@ -45,12 +45,17 @@ def teardown_method(self, method):
 
     @pytest.mark.slow
     def test_ts_plot_with_tz(self, tz_aware_fixture):
-        # GH2877, GH17173, GH31205
+        # GH2877, GH17173, GH31205, GH31580
         tz = tz_aware_fixture
         index = date_range("1/1/2011", periods=2, freq="H", tz=tz)
         ts = Series([188.5, 328.25], index=index)
         with tm.assert_produces_warning(None):
             _check_plot_works(ts.plot)
+            ax = ts.plot()
+            xdata = list(ax.get_lines())[0].get_xdata()
+            # Check first and last points' labels are correct
+            assert (xdata[0].hour, xdata[0].minute) == (0, 0)
+            assert (xdata[-1].hour, xdata[-1].minute) == (1, 0)
 
     def test_fontsize_set_correctly(self):
         # For issue #8765