1 /*
2 * Copyright 2003-2004 The Apache Software Foundation.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package org.apache.commons.math.stat.descriptive.moment;
17
18 import junit.framework.Test;
19 import junit.framework.TestSuite;
20
21 import org.apache.commons.math.stat.descriptive.StorelessUnivariateStatisticAbstractTest;
22 import org.apache.commons.math.stat.descriptive.UnivariateStatistic;
23
24 /**
25 * Test cases for the {@link UnivariateStatistic} class.
26 *
27 * @version $Revision: 155427 $ $Date: 2005-02-26 06:11:52 -0700 (Sat, 26 Feb 2005) $
28 */
29 public class SkewnessTest extends StorelessUnivariateStatisticAbstractTest{
30
31 protected Skewness stat;
32
33 /**
34 * @param name
35 */
36 public SkewnessTest(String name) {
37 super(name);
38 }
39
40 /* (non-Javadoc)
41 * @see org.apache.commons.math.stat.descriptive.UnivariateStatisticAbstractTest#getUnivariateStatistic()
42 */
43 public UnivariateStatistic getUnivariateStatistic() {
44 return new Skewness();
45 }
46
47 public static Test suite() {
48 TestSuite suite = new TestSuite(SkewnessTest.class);
49 suite.setName("Skewness Tests");
50 return suite;
51 }
52
53 /* (non-Javadoc)
54 * @see org.apache.commons.math.stat.descriptive.UnivariateStatisticAbstractTest#expectedValue()
55 */
56 public double expectedValue() {
57 return this.skew;
58 }
59
60 /**
61 * Make sure Double.NaN is returned iff n < 3
62 *
63 */
64 public void testNaN() {
65 Skewness skew = new Skewness();
66 assertTrue(Double.isNaN(skew.getResult()));
67 skew.increment(1d);
68 assertTrue(Double.isNaN(skew.getResult()));
69 skew.increment(1d);
70 assertTrue(Double.isNaN(skew.getResult()));
71 skew.increment(1d);
72 assertFalse(Double.isNaN(skew.getResult()));
73 }
74
75 }