def METHOD_NAME(self):
    mesh = g.trimesh.creation.icosahedron()
    # the icosahedron is centered at zero, so the true vertex
    # normal is just a unit vector of the vertex position
    truth = g.trimesh.util.unitize(mesh.vertices)
    # force fallback to loop normal summing by passing None
    # as the sparse matrix
    normals = g.trimesh.geometry.mean_vertex_normals(
        len(mesh.vertices),
        mesh.faces,
        mesh.face_normals)
    assert g.np.allclose(normals - truth, 0.0)
    # make sure the automatic sparse matrix generation works
    normals = g.trimesh.geometry.mean_vertex_normals(
        len(mesh.vertices),
        mesh.faces,
        mesh.face_normals)
    assert g.np.allclose(normals - truth, 0.0)
    # make sure the Trimesh normals- related attributes
    # are wired correctly
    assert mesh.faces_sparse is not None
    assert mesh.vertex_normals.shape == mesh.vertices.shape
    assert g.np.allclose(mesh.vertex_normals - truth, 0.0)