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Java example source code file (FakeTickerTest.java)

This example Java source code file (FakeTickerTest.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

callable, countdownlatch, exception, executorservice, expected, faketicker, faketickertest, gwtincompatible, illegalargumentexception, nullpointertester, override, testcase, threading, threads, timeunit, util, void

The FakeTickerTest.java Java example source code

/*
 * Copyright (C) 2008 The Guava Authors
 *
 * 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 com.google.common.testing;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

import junit.framework.TestCase;

import java.util.EnumSet;
import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * Unit test for {@link FakeTicker}.
 *
 * @author Jige Yu
 */
@GwtCompatible(emulated = true)
public class FakeTickerTest extends TestCase {

  @GwtIncompatible // NullPointerTester
  public void testNullPointerExceptions() {
    NullPointerTester tester = new NullPointerTester();
    tester.testAllPublicInstanceMethods(new FakeTicker());
  }

  public void testAdvance() {
    FakeTicker ticker = new FakeTicker();
    assertEquals(0, ticker.read());
    assertSame(ticker, ticker.advance(10));
    assertEquals(10, ticker.read());
    ticker.advance(1, TimeUnit.MILLISECONDS);
    assertEquals(1000010L, ticker.read());
  }

  public void testAutoIncrementStep_returnsSameInstance() {
    FakeTicker ticker = new FakeTicker();
    assertSame(ticker, ticker.setAutoIncrementStep(10, TimeUnit.NANOSECONDS));
  }

  public void testAutoIncrementStep_nanos() {
    FakeTicker ticker = new FakeTicker().setAutoIncrementStep(10, TimeUnit.NANOSECONDS);
    assertEquals(0, ticker.read());
    assertEquals(10, ticker.read());
    assertEquals(20, ticker.read());
  }

  public void testAutoIncrementStep_millis() {
    FakeTicker ticker = new FakeTicker().setAutoIncrementStep(1, TimeUnit.MILLISECONDS);
    assertEquals(0, ticker.read());
    assertEquals(1000000, ticker.read());
    assertEquals(2000000, ticker.read());
  }

  public void testAutoIncrementStep_seconds() {
    FakeTicker ticker = new FakeTicker().setAutoIncrementStep(3, TimeUnit.SECONDS);
    assertEquals(0, ticker.read());
    assertEquals(3000000000L, ticker.read());
    assertEquals(6000000000L, ticker.read());
  }

  public void testAutoIncrementStep_resetToZero() {
    FakeTicker ticker = new FakeTicker().setAutoIncrementStep(10, TimeUnit.NANOSECONDS);
    assertEquals(0, ticker.read());
    assertEquals(10, ticker.read());
    assertEquals(20, ticker.read());

    for (TimeUnit timeUnit : EnumSet.allOf(TimeUnit.class)) {
      ticker.setAutoIncrementStep(0, timeUnit);
      assertEquals(
          "Expected no auto-increment when setting autoIncrementStep to 0 " + timeUnit,
          30, ticker.read());
    }
  }

  public void testAutoIncrement_negative() {
    FakeTicker ticker = new FakeTicker();
    try {
      ticker.setAutoIncrementStep(-1, TimeUnit.NANOSECONDS);
      fail("Expected IllegalArgumentException");
    } catch (IllegalArgumentException expected) {
    }
  }

  @GwtIncompatible // concurrency

  public void testConcurrentAdvance() throws Exception {
    final FakeTicker ticker = new FakeTicker();

    int numberOfThreads = 64;
    runConcurrentTest(numberOfThreads,
        new Callable<Void>() {
          @Override
          public Void call() throws Exception {
            // adds two nanoseconds to the ticker
            ticker.advance(1L);
            Thread.sleep(10);
            ticker.advance(1L);
            return null;
          }
        });

    assertEquals(numberOfThreads * 2, ticker.read());
  }

  @GwtIncompatible // concurrency

  public void testConcurrentAutoIncrementStep() throws Exception {
    int incrementByNanos = 3;
    final FakeTicker ticker =
        new FakeTicker().setAutoIncrementStep(incrementByNanos, TimeUnit.NANOSECONDS);

    int numberOfThreads = 64;
    runConcurrentTest(numberOfThreads,
        new Callable<Void>() {
          @Override
          public Void call() throws Exception {
            ticker.read();
            return null;
          }
        });

    assertEquals(incrementByNanos * numberOfThreads, ticker.read());
  }

  /**
   * Runs {@code callable} concurrently {@code numberOfThreads} times.
   */
  @GwtIncompatible // concurrency
  private void runConcurrentTest(int numberOfThreads, final Callable<Void> callable)
      throws Exception {
    ExecutorService executorService = Executors.newFixedThreadPool(numberOfThreads);
    final CountDownLatch startLatch = new CountDownLatch(numberOfThreads);
    final CountDownLatch doneLatch = new CountDownLatch(numberOfThreads);
    for (int i = numberOfThreads; i > 0; i--) {
      executorService.submit(new Callable<Void>() {
        @Override
        public Void call() throws Exception {
          startLatch.countDown();
          startLatch.await();
          callable.call();
          doneLatch.countDown();
          return null;
        }
      });
    }
    doneLatch.await();
  }
}

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