def METHOD_NAME(self) -> None:
    """Test nan extrapolation."""
    self.grid.extrapolation = "nan"  # type: ignore[assignment]
    data = self.grid([-0.5, 0, 1.5])
    np.testing.assert_allclose(
        data[..., 0],
        [
            [np.nan, 0.976450, np.nan],
            [np.nan, 0.759385, np.nan],
        ],
        rtol=1e-6,
    )
    self.basis.extrapolation = "nan"  # type: ignore[assignment]
    data = self.basis([-0.5, 0, 1.5])
    np.testing.assert_allclose(
        data[..., 0],
        [
            [np.nan, 0.691735, np.nan],
            [np.nan, 1.056383, np.nan],
        ],
        rtol=1e-6,
    )