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17 package org.apache.commons.math4.legacy.stat.descriptive.moment;
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19 import org.apache.commons.math4.legacy.stat.descriptive.StorelessUnivariateStatisticAbstractTest;
20 import org.apache.commons.math4.legacy.stat.descriptive.UnivariateStatistic;
21 import org.junit.Assert;
22 import org.junit.Test;
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28 public class SkewnessTest extends StorelessUnivariateStatisticAbstractTest{
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30 protected Skewness stat;
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35 @Override
36 public UnivariateStatistic getUnivariateStatistic() {
37 return new Skewness();
38 }
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43 @Override
44 public double expectedValue() {
45 return this.skew;
46 }
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51 @Test
52 public void testNaN() {
53 Skewness skew = new Skewness();
54 Assert.assertTrue(Double.isNaN(skew.getResult()));
55 skew.increment(1d);
56 Assert.assertTrue(Double.isNaN(skew.getResult()));
57 skew.increment(1d);
58 Assert.assertTrue(Double.isNaN(skew.getResult()));
59 skew.increment(1d);
60 Assert.assertFalse(Double.isNaN(skew.getResult()));
61 }
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63 @Test
64 public void testZeroSkewness() {
65 final double[] values = {2, 2, 2, 2};
66 Assert.assertEquals(0, new Skewness().evaluate(values), 0.0);
67 }
68 }