/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.waveprotocol.wave.model.testing;
import junit.framework.TestCase;
import org.waveprotocol.wave.model.testing.RandomDocOpGenerator.RandomProvider;
public class RandomProviderImplTest extends TestCase {
static final int NUMBERS[] = { 0, 1, 2, 0x10000, 314159262, 0x7fffffff, 0x80000000, 0xffffffff };
static final int ITERATIONS = 1000;
static final double MAX_DEVIATION = 0.5; // 50% (takes about 5K iterations to lower this to 25%)
public void testNextInt1() {
assertEquals(0, RandomProviderImpl.ofSeed(42).nextInt(1));
}
public void testNextIntThrowsIllegalArgumentException() {
RandomProvider rp = RandomProviderImpl.ofSeed(42);
try {
rp.nextInt(0);
fail("should throw IllegalArgumentException");
} catch (IllegalArgumentException expected) {
// success
}
try {
rp.nextInt(0x80000000);
fail("should throw IllegalArgumentException");
} catch (IllegalArgumentException expected) {
// success
}
}
public void testNextIntDistribution() {
for (int seed : NUMBERS) {
for (int bound : new int[]{ 2, 3, 4, 7, 16, 33 }) {
RandomProvider rp = RandomProviderImpl.ofSeed(seed);
int counts[] = new int[bound];
for (int i = 0; i < ITERATIONS; i++) {
counts[rp.nextInt(bound)]++; // fails with index-out-of-range if nextInt goes wrong
}
for (int j = 0; j < bound; j++) {
assertTrue("seed " + seed + ", bound " + bound + ", index " + j + ", count " + counts[j],
counts[j] >= (1.0 - MAX_DEVIATION) / bound * ITERATIONS);
assertTrue("seed " + seed + ", bound " + bound + ", index " + j + ", count " + counts[j],
counts[j] <= (1.0 + MAX_DEVIATION) / bound * ITERATIONS);
}
}
}
}
public void testNextBooleanDistribution() {
for (int seed : NUMBERS) {
RandomProvider rp = RandomProviderImpl.ofSeed(seed);
int trueCount = 0;
for (int i = 0; i < ITERATIONS; i++) {
if (rp.nextBoolean()) {
trueCount++;
}
}
assertTrue("seed " + seed + ", trueCount " + trueCount,
trueCount >= (1.0 - MAX_DEVIATION) * 0.5 * ITERATIONS);
assertTrue("seed " + seed + ", trueCount " + trueCount,
trueCount <= (1.0 + MAX_DEVIATION) * 0.5 * ITERATIONS);
}
}
}