    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: 1.1 $ $Date: 2004/10/08 05:08:20 $
    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  }