def METHOD_NAME(self):
    data = np.fromfunction(lambda y, x: (y + x), (1000, 1000))
    lons = np.fromfunction(
        lambda y, x: -180 + (360.0 / 1000) * x, (1000, 1000))
    lats = np.fromfunction(
        lambda y, x: -90 + (180.0 / 1000) * y, (1000, 1000))
    grid = self.area_def.get_cartesian_coords()
    lons, lats, data = swath_from_cartesian_grid(grid, lons, lats, data,
                                                 7000)
    cross_sum = data.sum()
    expected = 20685125.0
    self.assertAlmostEqual(cross_sum, expected)