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Java example source code file (ValueServerTest.java)

This example Java source code file (ValueServerTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

before, exception, expecting, illegalstateexception, mathillegalstateexception, net, network, summarystatistics, test, url, util, valueserver, valueservertest, well19937c, zeroexception

The ValueServerTest.java Java example source code

/*
 * 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.apache.commons.math3.random;

import java.net.URL;
import java.util.Arrays;

import org.apache.commons.math3.RetryRunner;
import org.apache.commons.math3.exception.MathIllegalStateException;
import org.apache.commons.math3.exception.ZeroException;
import org.apache.commons.math3.stat.descriptive.SummaryStatistics;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;

/**
 * Test cases for the ValueServer class.
 *
 */

@RunWith(RetryRunner.class)
public final class ValueServerTest {

    private ValueServer vs = new ValueServer(new Well19937c(100));

    @Before
    public void setUp() {
        vs.setMode(ValueServer.DIGEST_MODE);
        URL url = getClass().getResource("testData.txt");
        vs.setValuesFileURL(url);
    }

    /**
      * Generate 1000 random values and make sure they look OK.<br>
      * Note that there is a non-zero (but very small) probability that
      * these tests will fail even if the code is working as designed.
      */
    @Test
    public void testNextDigest() throws Exception {
        double next = 0.0;
        double tolerance = 0.1;
        vs.computeDistribution();
        Assert.assertTrue("empirical distribution property",
            vs.getEmpiricalDistribution() != null);
        SummaryStatistics stats = new SummaryStatistics();
        for (int i = 1; i < 1000; i++) {
            next = vs.getNext();
            stats.addValue(next);
        }
        Assert.assertEquals("mean", 5.069831575018909, stats.getMean(), tolerance);
        Assert.assertEquals("std dev", 1.0173699343977738, stats.getStandardDeviation(),
            tolerance);

        vs.computeDistribution(500);
        stats = new SummaryStatistics();
        for (int i = 1; i < 1000; i++) {
            next = vs.getNext();
            stats.addValue(next);
        }
        Assert.assertEquals("mean", 5.069831575018909, stats.getMean(), tolerance);
        Assert.assertEquals("std dev", 1.0173699343977738, stats.getStandardDeviation(),
            tolerance);
    }

    /**
     * Verify that when provided with fixed seeds, stochastic modes
     * generate fixed sequences.  Verifies the fix for MATH-654.
     */
    @Test
    public void testFixedSeed() throws Exception {
        ValueServer valueServer = new ValueServer();
        URL url = getClass().getResource("testData.txt");
        valueServer.setValuesFileURL(url);
        valueServer.computeDistribution();
        checkFixedSeed(valueServer, ValueServer.DIGEST_MODE);
        checkFixedSeed(valueServer, ValueServer.EXPONENTIAL_MODE);
        checkFixedSeed(valueServer, ValueServer.GAUSSIAN_MODE);
        checkFixedSeed(valueServer, ValueServer.UNIFORM_MODE);
    }

    /**
     * Do the check for {@link #testFixedSeed()}
     * @param mode ValueServer mode
     */
    private void checkFixedSeed(ValueServer valueServer, int mode) throws Exception {
        valueServer.reSeed(1000);
        valueServer.setMode(mode);
        double[][] values = new double[2][100];
        for (int i = 0; i < 100; i++) {
            values[0][i] = valueServer.getNext();
        }
        valueServer.reSeed(1000);
        for (int i = 0; i < 100; i++) {
            values[1][i] = valueServer.getNext();
        }
        Assert.assertTrue(Arrays.equals(values[0], values[1]));
    }

    /**
      * Make sure exception thrown if digest getNext is attempted
      * before loading empiricalDistribution.
      */
    @Test
    public void testNextDigestFail() throws Exception {
        try {
            vs.getNext();
            Assert.fail("Expecting IllegalStateException");
        } catch (IllegalStateException ex) {}
    }

    @Test
    public void testEmptyReplayFile() throws Exception {
        try {
            URL url = getClass().getResource("emptyFile.txt");
            vs.setMode(ValueServer.REPLAY_MODE);
            vs.setValuesFileURL(url);
            vs.getNext();
            Assert.fail("an exception should have been thrown");
        } catch (MathIllegalStateException mise) {
            // expected behavior
        }
    }

    @Test
    public void testEmptyDigestFile() throws Exception {
        try {
            URL url = getClass().getResource("emptyFile.txt");
            vs.setMode(ValueServer.DIGEST_MODE);
            vs.setValuesFileURL(url);
            vs.computeDistribution();
            Assert.fail("an exception should have been thrown");
        } catch (ZeroException ze) {
            // expected behavior
        }
    }

    /**
     * Test ValueServer REPLAY_MODE using values in testData file.<br>
     * Check that the values 1,2,1001,1002 match data file values 1 and 2.
     * the sample data file.
     */
    @Test
    public void testReplay() throws Exception {
        double firstDataValue = 4.038625496201205;
        double secondDataValue = 3.6485326248346936;
        double tolerance = 10E-15;
        double compareValue = 0.0d;
        vs.setMode(ValueServer.REPLAY_MODE);
        vs.resetReplayFile();
        compareValue = vs.getNext();
        Assert.assertEquals(compareValue,firstDataValue,tolerance);
        compareValue = vs.getNext();
        Assert.assertEquals(compareValue,secondDataValue,tolerance);
        for (int i = 3; i < 1001; i++) {
           compareValue = vs.getNext();
        }
        compareValue = vs.getNext();
        Assert.assertEquals(compareValue,firstDataValue,tolerance);
        compareValue = vs.getNext();
        Assert.assertEquals(compareValue,secondDataValue,tolerance);
        vs.closeReplayFile();
        // make sure no NPE
        vs.closeReplayFile();
    }

    /**
     * Test other ValueServer modes
     */
    @Test
    public void testModes() throws Exception {
        vs.setMode(ValueServer.CONSTANT_MODE);
        vs.setMu(0);
        Assert.assertEquals("constant mode test",vs.getMu(),vs.getNext(),Double.MIN_VALUE);
        vs.setMode(ValueServer.UNIFORM_MODE);
        vs.setMu(2);
        double val = vs.getNext();
        Assert.assertTrue(val > 0 && val < 4);
        vs.setSigma(1);
        vs.setMode(ValueServer.GAUSSIAN_MODE);
        val = vs.getNext();
        Assert.assertTrue("gaussian value close enough to mean",
            val < vs.getMu() + 100*vs.getSigma());
        vs.setMode(ValueServer.EXPONENTIAL_MODE);
        val = vs.getNext();
        Assert.assertTrue(val > 0);
        try {
            vs.setMode(1000);
            vs.getNext();
            Assert.fail("bad mode, expecting IllegalStateException");
        } catch (IllegalStateException ex) {
            // ignored
        }
    }

    /**
     * Test fill
     */
    @Test
    public void testFill() throws Exception {
        vs.setMode(ValueServer.CONSTANT_MODE);
        vs.setMu(2);
        double[] val = new double[5];
        vs.fill(val);
        for (int i = 0; i < 5; i++) {
            Assert.assertEquals("fill test in place",2,val[i],Double.MIN_VALUE);
        }
        double v2[] = vs.fill(3);
        for (int i = 0; i < 3; i++) {
            Assert.assertEquals("fill test in place",2,v2[i],Double.MIN_VALUE);
        }
    }

    /**
     * Test getters to make Clover happy
     */
    @Test
    public void testProperties() throws Exception {
        vs.setMode(ValueServer.CONSTANT_MODE);
        Assert.assertEquals("mode test",ValueServer.CONSTANT_MODE,vs.getMode());
        vs.setValuesFileURL("http://www.apache.org");
        URL url = vs.getValuesFileURL();
        Assert.assertEquals("valuesFileURL test","http://www.apache.org",url.toString());
    }

}

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