/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.math4.legacy.stat.descriptive.moment;
  
  import org.apache.commons.math4.legacy.stat.descriptive.StorelessUnivariateStatisticAbstractTest;
  import org.apache.commons.math4.legacy.stat.descriptive.UnivariateStatistic;
  import org.junit.Assert;
  import org.junit.Test;
  
  /**
   * Test cases for the {@link UnivariateStatistic} class.
   */
  public class MeanTest extends StorelessUnivariateStatisticAbstractTest{
  
      protected Mean stat;
  
      /**
       * {@inheritDoc}
       */
      @Override
      public UnivariateStatistic getUnivariateStatistic() {
          return new Mean();
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public double expectedValue() {
          return this.mean;
      }
  
      /**Expected value for  the testArray defined in UnivariateStatisticAbstractTest */
      public double expectedWeightedValue() {
          return this.weightedMean;
      }
  
      @Test
      public void testSmallSamples() {
          Mean mean = new Mean();
          Assert.assertTrue(Double.isNaN(mean.getResult()));
          mean.increment(1d);
          Assert.assertEquals(1d, mean.getResult(), 0);
      }
  
      @Test
      public void testWeightedMean() {
          Mean mean = new Mean();
          Assert.assertEquals(expectedWeightedValue(), mean.evaluate(testArray, testWeightsArray, 0, testArray.length), getTolerance());
          Assert.assertEquals(expectedValue(), mean.evaluate(testArray, identicalWeightsArray, 0, testArray.length), getTolerance());
      }
  }