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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.rng.sampling.distribution;
18  
19  import org.apache.commons.rng.RestorableUniformRandomProvider;
20  import org.apache.commons.rng.UniformRandomProvider;
21  import org.apache.commons.rng.sampling.RandomAssert;
22  import org.apache.commons.rng.simple.RandomSource;
23  import org.junit.Test;
24  
25  /**
26   * Test for the {@link RejectionInversionZipfSampler}. The tests hit edge cases for the sampler.
27   */
28  public class RejectionInversionZipfSamplerTest {
29      /**
30       * Test the constructor with a bad number of elements.
31       */
32      @Test(expected = IllegalArgumentException.class)
33      public void testConstructorThrowsWithZeroNumberOfElements() {
34          final RestorableUniformRandomProvider rng =
35              RandomSource.create(RandomSource.SPLIT_MIX_64);
36          final int numberOfElements = 0;
37          final double exponent = 1;
38          RejectionInversionZipfSampler.of(rng, numberOfElements, exponent);
39      }
40  
41      /**
42       * Test the constructor with a bad exponent.
43       */
44      @Test(expected = IllegalArgumentException.class)
45      public void testConstructorThrowsWithZeroExponent() {
46          final RestorableUniformRandomProvider rng =
47              RandomSource.create(RandomSource.SPLIT_MIX_64);
48          final int numberOfElements = 1;
49          final double exponent = 0;
50          RejectionInversionZipfSampler.of(rng, numberOfElements, exponent);
51      }
52  
53      /**
54       * Test the SharedStateSampler implementation.
55       */
56      @Test
57      public void testSharedStateSampler() {
58          final UniformRandomProvider rng1 = RandomSource.create(RandomSource.SPLIT_MIX_64, 0L);
59          final UniformRandomProvider rng2 = RandomSource.create(RandomSource.SPLIT_MIX_64, 0L);
60          final int numberOfElements = 7;
61          final double exponent = 1.23;
62          final SharedStateDiscreteSampler sampler1 =
63              RejectionInversionZipfSampler.of(rng1, numberOfElements, exponent);
64          final SharedStateDiscreteSampler sampler2 = sampler1.withUniformRandomProvider(rng2);
65          RandomAssert.assertProduceSameSequence(sampler1, sampler2);
66      }
67  }