1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.math.stat.descriptive.moment;
18
19 import junit.framework.Test;
20 import junit.framework.TestSuite;
21
22 import org.apache.commons.math.stat.descriptive.StorelessUnivariateStatisticAbstractTest;
23 import org.apache.commons.math.stat.descriptive.UnivariateStatistic;
24
25 /**
26 * Test cases for the {@link UnivariateStatistic} class.
27 *
28 * @version $Revision: 762087 $ $Date: 2009-04-05 10:20:18 -0400 (Sun, 05 Apr 2009) $
29 */
30 public class SkewnessTest extends StorelessUnivariateStatisticAbstractTest{
31
32 protected Skewness stat;
33
34 /**
35 * @param name
36 */
37 public SkewnessTest(String name) {
38 super(name);
39 }
40
41 /**
42 * {@inheritDoc}
43 */
44 @Override
45 public UnivariateStatistic getUnivariateStatistic() {
46 return new Skewness();
47 }
48
49 public static Test suite() {
50 TestSuite suite = new TestSuite(SkewnessTest.class);
51 suite.setName("Skewness Tests");
52 return suite;
53 }
54
55 /**
56 * {@inheritDoc}
57 */
58 @Override
59 public double expectedValue() {
60 return this.skew;
61 }
62
63 /**
64 * Make sure Double.NaN is returned iff n < 3
65 *
66 */
67 public void testNaN() {
68 Skewness skew = new Skewness();
69 assertTrue(Double.isNaN(skew.getResult()));
70 skew.increment(1d);
71 assertTrue(Double.isNaN(skew.getResult()));
72 skew.increment(1d);
73 assertTrue(Double.isNaN(skew.getResult()));
74 skew.increment(1d);
75 assertFalse(Double.isNaN(skew.getResult()));
76 }
77
78 }