001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.math.stat.descriptive.moment; 018 019 import junit.framework.Test; 020 import junit.framework.TestSuite; 021 022 import org.apache.commons.math.stat.descriptive.StorelessUnivariateStatisticAbstractTest; 023 import org.apache.commons.math.stat.descriptive.UnivariateStatistic; 024 025 /** 026 * Test cases for the {@link UnivariateStatistic} class. 027 * 028 * @version $Revision: 762087 $ $Date: 2009-04-05 10:20:18 -0400 (Sun, 05 Apr 2009) $ 029 */ 030 public class SkewnessTest extends StorelessUnivariateStatisticAbstractTest{ 031 032 protected Skewness stat; 033 034 /** 035 * @param name 036 */ 037 public SkewnessTest(String name) { 038 super(name); 039 } 040 041 /** 042 * {@inheritDoc} 043 */ 044 @Override 045 public UnivariateStatistic getUnivariateStatistic() { 046 return new Skewness(); 047 } 048 049 public static Test suite() { 050 TestSuite suite = new TestSuite(SkewnessTest.class); 051 suite.setName("Skewness Tests"); 052 return suite; 053 } 054 055 /** 056 * {@inheritDoc} 057 */ 058 @Override 059 public double expectedValue() { 060 return this.skew; 061 } 062 063 /** 064 * Make sure Double.NaN is returned iff n < 3 065 * 066 */ 067 public void testNaN() { 068 Skewness skew = new Skewness(); 069 assertTrue(Double.isNaN(skew.getResult())); 070 skew.increment(1d); 071 assertTrue(Double.isNaN(skew.getResult())); 072 skew.increment(1d); 073 assertTrue(Double.isNaN(skew.getResult())); 074 skew.increment(1d); 075 assertFalse(Double.isNaN(skew.getResult())); 076 } 077 078 }