def test_extend(self):
n = Nansat(self.test_file_arctic, log_level=40, mapper=self.default_mapper)
nshape1 = n.shape()
n.extend(left=10, right=20, top=30, bottom=40)
be = n[1]
self.assertEqual(n.shape(), (nshape1[0]+70, nshape1[1]+30))
self.assertIsInstance(be, np.ndarray)
