@Test
public void testFloor() {

    // mostly tested in other tests
    AVLGroupTree x = new AVLGroupTree(false);
    for (int i = 0; i < 101; i++) {
        x.add(new Centroid(i / 2));
    }
    assertEquals(IntAVLTree.NIL, x.floor(-30));
    for (Centroid centroid : x) {
        assertEquals(centroid.mean(), x.mean(x.floor(centroid.mean() + 0.1)), 0);
    }
}