@Test(expected=IllegalStateException.class)
public void testFailSafeOnPotentialOverflow() {

  LongDiffNullArrayEdges edges = getEdges();
  List<Edge<LongWritable, NullWritable>> initialEdges = Lists.newArrayList(
      createEdge(5223372036854775807L), createEdge(-4223372036854775807L));
  edges.initialize(initialEdges);
}