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/*
* Copyright (C) 2019, Matthias Sohn <matthias.sohn@sap.com>
* and other copyright owners as documented in the project's IP log.
*
* This program and the accompanying materials are made available
* under the terms of the Eclipse Distribution License v1.0 which
* accompanies this distribution, is reproduced below, and is
* available at http://www.eclipse.org/org/documents/edl-v10.php
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* - Neither the name of the Eclipse Foundation, Inc. nor the
* names of its contributors may be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.eclipse.jgit.util;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import org.eclipse.jgit.util.Stats;
import org.junit.Test;
public class StatsTest {
@Test
public void testStatsTrivial() {
Stats s = new Stats();
s.add(1);
s.add(1);
s.add(1);
assertEquals(3, s.count());
assertEquals(1.0, s.min(), 1E-6);
assertEquals(1.0, s.max(), 1E-6);
assertEquals(1.0, s.avg(), 1E-6);
assertEquals(0.0, s.var(), 1E-6);
assertEquals(0.0, s.stddev(), 1E-6);
}
@Test
public void testStats() {
Stats s = new Stats();
s.add(1);
s.add(2);
s.add(3);
s.add(4);
assertEquals(4, s.count());
assertEquals(1.0, s.min(), 1E-6);
assertEquals(4.0, s.max(), 1E-6);
assertEquals(2.5, s.avg(), 1E-6);
assertEquals(1.666667, s.var(), 1E-6);
assertEquals(1.290994, s.stddev(), 1E-6);
}
@Test
/**
* see
* https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Example
*/
public void testStatsCancellationExample1() {
Stats s = new Stats();
s.add(1E8 + 4);
s.add(1E8 + 7);
s.add(1E8 + 13);
s.add(1E8 + 16);
assertEquals(4, s.count());
assertEquals(1E8 + 4, s.min(), 1E-6);
assertEquals(1E8 + 16, s.max(), 1E-6);
assertEquals(1E8 + 10, s.avg(), 1E-6);
assertEquals(30, s.var(), 1E-6);
assertEquals(5.477226, s.stddev(), 1E-6);
}
@Test
/**
* see
* https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Example
*/
public void testStatsCancellationExample2() {
Stats s = new Stats();
s.add(1E9 + 4);
s.add(1E9 + 7);
s.add(1E9 + 13);
s.add(1E9 + 16);
assertEquals(4, s.count());
assertEquals(1E9 + 4, s.min(), 1E-6);
assertEquals(1E9 + 16, s.max(), 1E-6);
assertEquals(1E9 + 10, s.avg(), 1E-6);
assertEquals(30, s.var(), 1E-6);
assertEquals(5.477226, s.stddev(), 1E-6);
}
@Test
public void testNoValues() {
Stats s = new Stats();
assertTrue(Double.isNaN(s.var()));
assertTrue(Double.isNaN(s.stddev()));
assertTrue(Double.isNaN(s.avg()));
assertTrue(Double.isNaN(s.min()));
assertTrue(Double.isNaN(s.max()));
s.add(42.3);
assertTrue(Double.isNaN(s.var()));
assertTrue(Double.isNaN(s.stddev()));
assertEquals(42.3, s.avg(), 1E-6);
assertEquals(42.3, s.max(), 1E-6);
assertEquals(42.3, s.min(), 1E-6);
s.add(42.3);
assertEquals(0, s.var(), 1E-6);
assertEquals(0, s.stddev(), 1E-6);
}
}