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 /** Toy RNG to ensure we get predictable numbers during unit tests. */
47 public class TestRng {
48 private int next;
49
50 /**
51 * Create a new random number generator, seeded by a string.
52 *
53 * @param seed
54 * seed to bootstrap, usually this is the test method name.
55 */
56 public TestRng(final String seed) {
57 next = 0;
58 for (int i = 0; i < seed.length(); i++)
59 next = next * 11 + seed.charAt(i);
60 }
61
62 /**
63 * Get the next {@code cnt} bytes of random data.
64 *
65 * @param cnt
66 * number of random bytes to produce.
67 * @return array of {@code cnt} randomly generated bytes.
68 */
69 public byte[] nextBytes(final int cnt) {
70 final byte[] r = new byte[cnt];
71 for (int i = 0; i < cnt; i++)
72 r[i] = (byte) nextInt();
73 return r;
74 }
75
76 /**
77 * @return the next random integer.
78 */
79 public int nextInt() {
80 next = next * 1103515245 + 12345;
81 return next;
82 }
83 }