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.core.source32;
18
19 import org.junit.jupiter.api.Assertions;
20 import org.junit.jupiter.api.Test;
21 import org.junit.jupiter.params.ParameterizedTest;
22 import org.junit.jupiter.params.provider.CsvSource;
23
24 /**
25 * The tests the caching of calls to {@link IntProvider#nextInt()} are used as
26 * the source for {@link IntProvider#nextInt()} and
27 * {@link IntProvider#nextBoolean()}.
28 */
29 class IntProviderTest {
30 /**
31 * A simple class to flip the bits in a number as the source for
32 * {@link IntProvider#next()}.
33 */
34 static final class FlipIntProvider extends IntProvider {
35 /** The value. */
36 private int value;
37
38 /**
39 * @param value the value
40 */
41 FlipIntProvider(int value) {
42 // Flip the bits so the first call to next() returns to the same state
43 this.value = ~value;
44 }
45
46 @Override
47 public int next() {
48 // Flip the bits
49 value = ~value;
50 return value;
51 }
52 }
53
54 /**
55 * This test ensures that the call to {@link IntProvider#nextBoolean()} returns
56 * each of the bits from a call to {@link IntProvider#nextInt()}.
57 *
58 * <p>The order should be from the least-significant bit.
59 */
60 @Test
61 void testNextBoolean() {
62 for (int i = 0; i < Integer.SIZE; i++) {
63 // Set only a single bit in the source
64 final int value = 1 << i;
65 final IntProvider provider = new FlipIntProvider(value);
66 // Test the result for a single pass over the long
67 for (int j = 0; j < Integer.SIZE; j++) {
68 final boolean expected = i == j;
69 final int index = j;
70 Assertions.assertEquals(expected, provider.nextBoolean(), () -> "Pass 1, bit " + index);
71 }
72 // The second pass should use the opposite bits
73 for (int j = 0; j < Integer.SIZE; j++) {
74 final boolean expected = i != j;
75 final int index = j;
76 Assertions.assertEquals(expected, provider.nextBoolean(), () -> "Pass 2, bit " + index);
77 }
78 }
79 }
80
81 @ParameterizedTest
82 @CsvSource({
83 // OK
84 "10, 0, 10",
85 "10, 5, 5",
86 "10, 9, 1",
87 // Allowed edge cases
88 "0, 0, 0",
89 "10, 10, 0",
90 // Bad
91 "10, 0, 11",
92 "10, 10, 1",
93 "10, 10, 2147483647",
94 "10, 0, -1",
95 "10, 5, -1",
96 })
97 void testNextBytesIndices(int size, int start, int len) {
98 final FlipIntProvider rng = new FlipIntProvider(999);
99 final byte[] bytes = new byte[size];
100 // Be consistent with System.arraycopy
101 try {
102 System.arraycopy(bytes, start, bytes, start, len);
103 } catch (IndexOutOfBoundsException ex) {
104 // nextBytes should throw under the same conditions.
105 // Note: This is not ArrayIndexOutOfBoundException to be
106 // future compatible with Objects.checkFromIndexSize.
107 Assertions.assertThrows(IndexOutOfBoundsException.class, () ->
108 rng.nextBytes(bytes, start, len));
109 return;
110 }
111 rng.nextBytes(bytes, start, len);
112 }
113 }