HistogramTest.java

/*******************************************************************************
 * Copyright (c) 2005, 2014 springside.github.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 *******************************************************************************/
package org.springside.modules.metrics;

import static org.assertj.core.api.Assertions.*;

import org.junit.Test;

public class HistogramTest {

	@Test
	public void normal() {
		Histogram histogram = new Histogram(90d, 95d);

		for (int i = 1; i <= 100; i++) {
			histogram.update(i);
		}

		HistogramMetric metric = histogram.calculateMetric();

		assertThat(metric.min).isEqualTo(1);
		assertThat(metric.max).isEqualTo(100);
		assertThat(metric.mean).isEqualTo(50.5);
		assertThat(metric.pcts.get(90d)).isEqualTo(90);
		assertThat(metric.pcts.get(95d)).isEqualTo(95);

		for (int i = 1; i <= 100; i++) {
			histogram.update(i * 2);
		}

		metric = histogram.calculateMetric();

		assertThat(metric.min).isEqualTo(2);
		assertThat(metric.max).isEqualTo(200);
		assertThat(metric.mean).isEqualTo(101);
		assertThat(metric.pcts.get(90d)).isEqualTo(180);
		assertThat(metric.pcts.get(95d)).isEqualTo(190);
	}

	@Test
	public void fewData() {
		Histogram histogram = new Histogram(90d, 95d);

		histogram.update(1);
		HistogramMetric metric = histogram.calculateMetric();
		assertThat(metric.pcts.get(90d)).isEqualTo(1);
		assertThat(metric.pcts.get(95d)).isEqualTo(1);

		for (int i = 1; i <= 3; i++) {
			histogram.update(i);
		}
		metric = histogram.calculateMetric();

		assertThat(metric.min).isEqualTo(1);
		assertThat(metric.max).isEqualTo(3);
		assertThat(metric.mean).isEqualTo(2);
		assertThat(metric.pcts.get(90d)).isEqualTo(3);
		assertThat(metric.pcts.get(95d)).isEqualTo(3);
	}

	@Test
	public void emptyMesures() {
		Histogram histogram = new Histogram(90d, 95d);

		HistogramMetric metric = histogram.calculateMetric();

		assertThat(metric.min).isZero();
		assertThat(metric.max).isZero();
		assertThat(metric.mean).isZero();
		assertThat(metric.pcts.get(90d)).isZero();
	}

	@Test()
	public void emptyPcts() {
		Histogram histogram = new Histogram();
		for (int i = 1; i <= 3; i++) {
			histogram.update(i);
		}

		HistogramMetric metric = histogram.calculateMetric();
		assertThat(metric.max).isEqualTo(3);
		assertThat(metric.pcts).isEmpty();
		assertThat(metric.pcts.get(90d)).isNull();
	}
}