/**
* Copyright 2009 Google Inc.
*
* Licensed 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.util;
import junit.framework.TestCase;
import org.waveprotocol.wave.model.util.FuzzingBackOffGenerator.BackOffParameters;
/**
* Test for FuzzingBackOffGenerator.
*
* @author zdwang@google.com (David Wang)
*/
public class FuzzingBackOffGeneratorTest extends TestCase {
public void testSimple() {
FuzzingBackOffGenerator generator = new FuzzingBackOffGenerator(2, 1000, 0.5);
// this number is fibonacci
BackOffParameters next = generator.next();
expectRange(next.targetDelay, 2, 3);
expectRange(next.minimumDelay, 1, 2);
next = generator.next();
expectRange(next.targetDelay, 2, 3);
expectRange(next.minimumDelay, 1, 3);
next = generator.next();
expectRange(next.targetDelay, 4, 6);
expectRange(next.minimumDelay, 2, 4);
next = generator.next();
expectRange(next.targetDelay, 6, 9);
expectRange(next.minimumDelay, 3, 6);
for (int i = 0; i < 100; i++) {
generator.next();
}
next = generator.next();
expectRange(next.targetDelay, 1000, 1500);
expectRange(next.minimumDelay, 500, 1000);
}
private void expectRange(int value, int min, int max) {
assertTrue("expected " + min + " <= (value) " + value, min <= value);
assertTrue("expected " + max + " >= (value) " + value, value <= max);
}
public void testIllegalArgument() {
try {
new FuzzingBackOffGenerator(2, 1000, 2);
fail("Should not be able to create FuzzingBackOffGenerator with bad randomisationFactor");
} catch (IllegalArgumentException ex) {
// Expected
}
try {
new FuzzingBackOffGenerator(0, 1000, 0.5);
fail("Should not be able to create FuzzingBackOffGenerator with bad initialBackOff");
} catch (IllegalArgumentException ex) {
// Expected
}
}
public void testReset() {
FuzzingBackOffGenerator generator = new FuzzingBackOffGenerator(2, 1000, 0.5);
BackOffParameters next = generator.next();
expectRange(next.targetDelay, 2, 3);
expectRange(next.minimumDelay, 1, 2);
next = generator.next();
expectRange(next.targetDelay, 2, 3);
expectRange(next.minimumDelay, 1, 2);
next = generator.next();
expectRange(next.targetDelay, 4, 6);
expectRange(next.minimumDelay, 2, 4);
generator.reset();
next = generator.next();
expectRange(next.targetDelay, 2, 3);
expectRange(next.minimumDelay, 1, 2);
next = generator.next();
expectRange(next.targetDelay, 2, 3);
expectRange(next.minimumDelay, 1, 2);
next = generator.next();
expectRange(next.targetDelay, 4, 6);
expectRange(next.minimumDelay, 2, 4);
}
/**
* Rather than trying to inject a random number generator to such a tiny clas, such an overkill,
* let's do something simple
*/
public void testGeneratesRamdomNumber() {
FuzzingBackOffGenerator generator = new FuzzingBackOffGenerator(2000, 10000, 0.5);
for (int i = 0; i < 100; i++) {
if (generator.next().targetDelay != 2000) {
return;
}
}
fail("100x same value, it's not random.");
}
public void testMaxReachedImmediately() {
FuzzingBackOffGenerator generator = new FuzzingBackOffGenerator(5, 2, 0.5);
BackOffParameters next = generator.next();
expectRange(next.targetDelay, 2, 3);
expectRange(next.minimumDelay, 1, 2);
next = generator.next();
expectRange(next.targetDelay, 2, 3);
expectRange(next.minimumDelay, 1, 2);
next = generator.next();
expectRange(next.targetDelay, 2, 3);
expectRange(next.minimumDelay, 1, 2);
}
}