cassandra-trunk/test/unit/org/apache/cassandra/gms/ArrayBackedBoundedStatsTest.java
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 * to you under the Apache License, Version 2.0 (the
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package org.apache.cassandra.gms;

import java.util.Arrays;

import org.junit.Test;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

public class ArrayBackedBoundedStatsTest {

    @Test
    public void test()
    {
        int size = 4;

        ArrayBackedBoundedStats bsd = new ArrayBackedBoundedStats(size);
        //check the values for an empty result
        assertEquals(0, bsd.mean(), 0.001d);

        bsd.add(1L); //this one falls out, over limit
        bsd.add(2L);
        bsd.add(3L);
        bsd.add(4L);
        bsd.add(5L);

        //verify that everything is in there
        long [] expected = new long[] {2,3,4,5};
        assertArrivalIntervals(bsd, expected);

        //check results
        assertEquals(3.5, bsd.mean(), 0.001d);
    }

    private void assertArrivalIntervals(ArrayBackedBoundedStats bsd, long [] expected)
    {
        Arrays.sort(expected);
        Arrays.sort(bsd.getArrivalIntervals());
        assertTrue(Arrays.equals(bsd.getArrivalIntervals(), expected));

    }

    @Test
    public void testMultipleRounds() throws Exception
    {
        int size = 5;
        ArrayBackedBoundedStats bsd = new ArrayBackedBoundedStats(size);

        for(long i=0; i <= 1000;i++)
        {
            bsd.add(i);
        }

        long [] expected = new long[] {1000,999,998,997, 996};
        assertArrivalIntervals(bsd, expected);
    }
}
