RestDownsamplerTest.java

package org.yamcs.web.rest.archive;

import static org.junit.Assert.assertEquals;

import java.util.List;

import org.junit.Test;
import org.yamcs.web.rest.archive.RestDownsampler.Sample;

public class RestDownsamplerTest {
    
    @Test
    public void testSampling() {
        RestDownsampler sampler = new RestDownsampler(10, 3);
        
        List<Sample> samples = sampler.collect();
        assertEquals(0, samples.size());
        
        sampler.process(1, 5);
        
        samples = sampler.collect();
        assertEquals(1, samples.size());
        assertEquals(5, samples.get(0).avg, 1e-10);
        assertEquals(1, samples.get(0).n);
        
        // Add to same bucket
        sampler.process(2, 10);
        assertEquals(1, samples.size());
        assertEquals((5+10)/2., samples.get(0).avg, 1e-10);
        assertEquals(2, samples.get(0).n);
        
        // Add to same bucket
        sampler.process(3, 7);
        samples = sampler.collect();
        assertEquals(1, samples.size());
        assertEquals((5+10+7)/3., samples.get(0).avg, 1e-10);
        assertEquals(3, samples.get(0).n);
        
        // Due to flooring, leads to a new bucket
        sampler.process(4, 2);
        samples = sampler.collect();
        assertEquals(2, samples.size());
        
        Sample sample0 = samples.get(0);
        assertEquals((5+10+7)/3., sample0.avg, 1e-10);
        assertEquals(5, sample0.min, 1e-10);
        assertEquals(10, sample0.max, 1e-10);
        
        Sample sample1 = samples.get(1);
        assertEquals(2, sample1.avg, 1e-10);
        assertEquals(2, sample1.min, 1e-10);
        assertEquals(2, sample1.max, 1e-10);
    }
}