def METHOD_NAME(self):
    self.sphere_settings[Tags.STRUCTURE_START_MM] = [0, 0, 0]
    self.sphere_settings[Tags.STRUCTURE_RADIUS_MM] = np.sqrt(3*1)     # diagonal of exactly one voxel
    ss = SphericalStructure(self.global_settings, self.sphere_settings)
    assert ss.geometrical_volume[0, 0, 0] == 1
    assert 0 < ss.geometrical_volume[0, 0, 1] < 1
    assert 0 < ss.geometrical_volume[1, 0, 0] < 1
    assert 0 < ss.geometrical_volume[1, 0, 1] < 1
    assert 0 < ss.geometrical_volume[0, 1, 0] < 1
    assert 0 < ss.geometrical_volume[0, 1, 1] < 1
    assert 0 < ss.geometrical_volume[1, 1, 0] < 1
    assert ss.geometrical_volume[1, 1, 1] == 0