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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 }
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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 }
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53
54
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 }