VarIntUtilTest.java

package org.yamcs.utils;

import static org.junit.Assert.*;

import java.nio.ByteBuffer;

import org.junit.Test;

public class VarIntUtilTest {

    @Test
    public void testVarInt32() throws Exception{
        ByteBuffer bb = ByteBuffer.allocate(10);
        VarIntUtil.writeVarInt32(bb, 3);
        assertEquals(1, bb.position());

        bb.rewind();
        assertEquals(3, VarIntUtil.readVarInt32(bb));

        bb.rewind();
        VarIntUtil.writeVarInt32(bb, 200);
        assertEquals(2, bb.position());
        bb.rewind();
        assertEquals(200, VarIntUtil.readVarInt32(bb));

        bb.rewind();
        VarIntUtil.writeVarInt32(bb, 0xFFFF);
        assertEquals(3, bb.position());
        bb.rewind();
        assertEquals(0xFFFF, VarIntUtil.readVarInt32(bb));

        bb.rewind();
        VarIntUtil.writeVarInt32(bb, 0xFFFFFFFF);
        assertEquals(5, bb.position());
        bb.rewind();
        assertEquals(0xFFFFFFFF, VarIntUtil.readVarInt32(bb));
    }

    @Test
    public void testInvalid() {
        ByteBuffer bb = ByteBuffer.wrap(StringConverter.hexStringToArray("8182838485"));
        try {
            VarIntUtil.readVarInt32(bb);
            fail("Should have thrown an exception");
        } catch (DecodingException e) {
        }
    }

    @Test
    public void testDeltaDeltaZigZag() throws Exception{
        int n = 100;
        int[] a= new int[n];
        for(int i=0;i<n;i++) {
            a[i]=i;
        }
        
        int[] ddz = VarIntUtil.encodeDeltaDeltaZigZag(a);
        assertEquals(n, ddz.length);
        assertEquals(0, ddz[0]);
        assertEquals(2, ddz[1]);
        for(int i=2; i<n; i++) {
            assertEquals(0, ddz[i]);
        }
        int[] b = VarIntUtil.decodeDeltaDeltaZigZag(ddz);
        assertArrayEquals(a,  b);
        
        for(int i=0;i<n;i++) {
            a[i]= -i;
        }
        ddz = VarIntUtil.encodeDeltaDeltaZigZag(a);
        b = VarIntUtil.decodeDeltaDeltaZigZag(ddz);
        assertArrayEquals(a,  b);
        
        for(int i=0; i<n; i++) {
            a[i]= (1<<31)+i * (((i&1)<<1)-1);
        }
        ddz = VarIntUtil.encodeDeltaDeltaZigZag(a);
        b = VarIntUtil.decodeDeltaDeltaZigZag(ddz);
        assertArrayEquals(a,  b);
        
    }
    
    
}