RandomOrderHashMapTest.java

package org.limewire.collection;

import java.util.Collection;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import junit.framework.Test;

import org.limewire.util.BaseTestCase;

@SuppressWarnings("unchecked")
public class RandomOrderHashMapTest extends BaseTestCase {
    public RandomOrderHashMapTest(String name) {
        super(name);
    }
    
    public static Test suite() {
        return buildTestSuite(RandomOrderHashMapTest.class);
    }
    
    /**
     * tests that two subsequent iterations over the same map
     * will return the elements in different order.
     */
    public void testRandomOrder() throws Exception {
        Map m = new RandomOrderHashMap(50);
        for (int i = 0; i < 50; i++)
            m.put(i, i + "x" + i);
        String out1 = "";
        String out2 = "";
        Set s = m.entrySet();
        for (Object o : s)
            out1 = out1 + o;
        for (Object o : s)
            out2 = out2 + o;
        assertNotEquals(out1, out2);
        
        out1 = "";
        out2 = "";
        s = m.keySet();
        for (Object o : s)
            out1 = out1 + o;
        for (Object o : s)
            out2 = out2 + o;
        assertNotEquals(out1, out2);
        
        out1 = "";
        out2 = "";
        Collection c = m.values();
        for (Object o : c)
            out1 = out1 + o;
        for (Object o : c)
            out2 = out2 + o;
        assertNotEquals(out1, out2);
    }
    
    public void testAllKeysInKeySet() {
        testAllKeysFor(200);
        testAllKeysFor(1);
        testAllKeysFor(199);
        // powers of two and values around
        testAllKeysFor(16);
        testAllKeysFor(15);
        testAllKeysFor(17);
        testAllKeysFor(2);
    }
    
    private void testAllKeysFor(int size) {
        RandomOrderHashMap<Integer, Integer> map = new RandomOrderHashMap<Integer, Integer>(size);
        Set<Integer> set = new HashSet<Integer>();
        // overfill it by one
        for (int i = 1; i <= size + 1; i++) {
            map.put(i, i);
            set.add(i);
        }
        assertEquals(size, map.keySet().size());
        for (Integer key : map.keySet()) {
            set.remove(key);
        }
        assertEquals("set: " + set + "for size " + size, 1, set.size());
    }
}