@Test
public void testRemoveChild() {

    mItemGroup.addChild(CHILD_1);
    mItemGroup.addChild(CHILD_2);
    mItemGroup.addChild(CHILD_3);
    mItemGroup.removeChild(CHILD_2);
    assertSame("Item at position 0 should be child1", CHILD_1, mItemGroup.getItemAt(0));
    assertSame("Item at position 1 should be child3", CHILD_3, mItemGroup.getItemAt(1));
    assertEquals("Should have 2 children", 2, mItemGroup.getCount());
    verify(mObserver).onItemRangeRemoved(eq(mItemGroup), eq(1), eq(1));
}