rebased on master
@@ -5,6 +5,9 @@ from numpy.testing import assert_allclose
import numpy as np
import astropy.units as u
from ...utils.testing import requires_data
+from gammapy.utils.testing import requires_data
+from gammapy.utils.nddata import NDDataArray
+from gammapy.irf import EffectiveAreaTable, EnergyDispersion
from ..sensitivity import SensitivityEstimator
