def test_reduce_sum(self):
flat_data = np.arange(4).astype('float')
cube = Cube((2, 2), flat_data)
cube0 = cube.reduce_sum((0, ), keepdims=True)
cube1 = cube.reduce_sum((1, ), keepdims=True)
cube01 = cube.reduce_sum((0, 1), keepdims=True)
np.testing.assert_equal(np.array([2., 4., 2., 4.]), cube0.flat)
np.testing.assert_equal(np.array([1., 1., 5., 5.]), cube1.flat)
np.testing.assert_equal(np.array([6., 6., 6., 6.]), cube01.flat)
