1 /*
2 * Copyright (C) 2008-2010, Google Inc.
3 * and other copyright owners as documented in the project's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 package org.eclipse.jgit.junit;
45
46 /**
47 * Toy RNG to ensure we get predictable numbers during unit tests.
48 */
49 public class TestRng {
50 private int next;
51
52 /**
53 * Create a new random number generator, seeded by a string.
54 *
55 * @param seed
56 * seed to bootstrap, usually this is the test method name.
57 */
58 public TestRng(String seed) {
59 next = 0;
60 for (int i = 0; i < seed.length(); i++)
61 next = next * 11 + seed.charAt(i);
62 }
63
64 /**
65 * Get the next {@code cnt} bytes of random data.
66 *
67 * @param cnt
68 * number of random bytes to produce.
69 * @return array of {@code cnt} randomly generated bytes.
70 */
71 public byte[] nextBytes(int cnt) {
72 final byte[] r = new byte[cnt];
73 for (int i = 0; i < cnt; i++)
74 r[i] = (byte) nextInt();
75 return r;
76 }
77
78 /**
79 * Next int
80 *
81 * @return the next random integer.
82 */
83 public int nextInt() {
84 next = next * 1103515245 + 12345;
85 return next;
86 }
87 }