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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.junit.Test;
20  import org.apache.commons.rng.UniformRandomProvider;
21  import org.apache.commons.rng.sampling.RandomAssert;
22  import org.apache.commons.rng.simple.RandomSource;
23  
24  /**
25   * Test for {@link ZigguratNormalizedGaussianSampler}.
26   */
27  public class ZigguratNormalizedGaussianSamplerTest {
28      // Cf. RNG-56
29      @Test(expected = StackOverflowError.class)
30      public void testInfiniteLoop() {
31          // A bad implementation whose only purpose is to force access
32          // to the rarest branch.
33          final UniformRandomProvider bad = new UniformRandomProvider() {
34                  // CHECKSTYLE: stop all
35                  public long nextLong(long n) { return 0; }
36                  public long nextLong() { return Long.MAX_VALUE; }
37                  public int nextInt(int n) { return 0; }
38                  public int nextInt() { return Integer.MAX_VALUE; }
39                  public float nextFloat() { return 1; }
40                  public double nextDouble() { return 1;}
41                  public void nextBytes(byte[] bytes, int start, int len) {}
42                  public void nextBytes(byte[] bytes) {}
43                  public boolean nextBoolean() { return false; }
44                  // CHECKSTYLE: resume all
45              };
46  
47          // Infinite loop (in v1.1).
48          new ZigguratNormalizedGaussianSampler(bad).sample();
49      }
50  
51      /**
52       * Test the SharedStateSampler implementation.
53       */
54      @Test
55      public void testSharedStateSampler() {
56          final UniformRandomProvider rng1 = RandomSource.create(RandomSource.SPLIT_MIX_64, 0L);
57          final UniformRandomProvider rng2 = RandomSource.create(RandomSource.SPLIT_MIX_64, 0L);
58          final SharedStateContinuousSampler sampler1 =
59              ZigguratNormalizedGaussianSampler.<ZigguratNormalizedGaussianSampler>of(rng1);
60          final SharedStateContinuousSampler sampler2 = sampler1.withUniformRandomProvider(rng2);
61          RandomAssert.assertProduceSameSequence(sampler1, sampler2);
62      }
63  }