def setUp(self) -> None:
        """
        Create a DataArray with a time-axis that contains datetime objects.
        """
        month = np.arange(1, 13, 1)
        data = np.sin(2 * np.pi * month / 12.0)
        times = pd.date_range(start="2017-01-01", freq="MS", periods=12)
        darray = DataArray(data, dims=["time"], coords=[times])

        self.darray = darray

        Create a DataArray with a time-axis that contains datetime objects.
        
xarray/tests/test_plot.py