Mercurial > hg > Members > kono > jpf-core
view src/tests/gov/nasa/jpf/util/OATHashTest.java @ 0:61d41facf527
initial v8 import (history reset)
author | Peter Mehlitz <Peter.C.Mehlitz@nasa.gov> |
---|---|
date | Fri, 23 Jan 2015 10:14:01 -0800 |
parents | |
children |
line wrap: on
line source
/* * Copyright (C) 2014, United States Government, as represented by the * Administrator of the National Aeronautics and Space Administration. * All rights reserved. * * The Java Pathfinder core (jpf-core) platform is licensed under the * Apache License, Version 2.0 (the "License"); you may not use this file except * in compliance with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0. * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package gov.nasa.jpf.util; import java.util.HashSet; import java.util.Random; import org.junit.Test; import gov.nasa.jpf.util.test.TestJPF; import static gov.nasa.jpf.util.OATHash.*; /** * just the very basic sanity checks for a hash function. * <2do> should add a test for uniformity of hash vals and measure collisions in medium bin size constraints */ public class OATHashTest extends TestJPF { @Test public void testRandom(){ int maxRounds = 256; int maxKey = 8; Random r = new Random(42); HashSet<Integer> seen = new HashSet<Integer>(); // not very smart, but the number of rounds is reasonably small for (int i=0; i<maxRounds; i++){ int h = 0; for (int j=0; j<maxKey; j++){ int x = r.nextInt(); h = hashMixin(h, x); if (j>0){ System.out.print(','); } System.out.print(Integer.toHexString(x)); } h = hashFinalize(h); System.out.print(" => "); System.out.println(h); if (seen.contains(h)){ fail("collision on round " + i); } seen.add(h); } } @Test public void testRandomSmall(){ int maxRounds = 256; int maxKey = 4; int maxVal = 32; Random r = new Random(42); HashSet<Integer> seen = new HashSet<Integer>(); // not very smart, but the number of rounds is reasonably small for (int i=0; i<maxRounds; i++){ int h = 0; for (int j=0; j<maxKey; j++){ int x = r.nextInt(maxVal); h = hashMixin(h, x); if (j>0){ System.out.print(','); } System.out.print(x); } h = hashFinalize(h); System.out.print(" => "); System.out.println(h); if (seen.contains(h)){ fail("collision on round " + i); } seen.add(h); } } }