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JUnit Toolkit enhances JUnit with performance testing, asymptotic behaviour analysis, and concurrency testing.
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/*
 * Copyright The Sett Ltd, 2005 to 2014.
 *
 * 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.thesett.junit.extensions;

/**
 * A TimingController is an interface that a test that is aware of the fact that it is being timed can use to register
 * its own timings giving finer control over the exact wall-clock interval used, and allowing tests to register multiple
 * timings.
 *
 * Using this interface tests can suspend and resume test timers. This is usefull if you want to exclude some
 * expensive preparation from being timed as part of a test. In general when timing tests to measure the performance of
 * code, you should try to set up data in the #setUp where possible, or as static members in the test class. This is not
 * always convenient, this interface gives you a way to suspend and resume, or event completely restart test timers, to
 * get accurate measurements.
 *
 * 
The interface can also be used to register multiple test pass/fails and timings from a single test method. In
 * some cases it is easier to write tests in this way. For example a concurrent and asynchronous test may make many
 * asynchronous requests and then wait for replies to all its requests. Writing such a test with one send/reply per test
 * method and trying to scale up using many threads will quickly run into limitations if more than about 100
 * asynchronous calls need to be made at once. A better way to write such a test is as a single method that sends many
 * (perhaps thousands or millions) and waits for replies in two threads, one for send, one for replies. It can then log
 * pass/fails and timings on each individual reply as they come back in, even though the test has been written to send
 * thousands of requests per test method in order to do volume testing.
 *
 * 
If when the {@link #completeTest(boolean)} is called, the test runner decides that testing should stop (perhaps
 * because a duration test has expired), it throws an InterruptedException to indicate that the test method should stop
 * immediately. The test method can do this by allowing this exception to fall through, if no other clean-up handling is
 * necessary, or it can simply return as soon as it possibly can. The test runner will still call the tearDown method in
 * the usual way when this happens.
 *
 * 
Below are some examples of how this can be used. Note how checking that the timing controller is really available
 * rather than assuming it is, means that the test can run as an ordinary JUnit test under the default test runners. In
 * general code should be written to take advantage of the extended capabilities of junit toolkit, without assuming they
 * are going to be run under its test runner.
 *
 * 
 * public class MyTest extends TestCase implements TimingControllerAware {
 * ...
 *
 *    timingUtils = this.getTimingController();
 *
 *    // Do expensive data preparation here...
 *
 *    if (timingUtils != null)
 *        timingUtils.restart();
 * 
 *
 *  * public class MyTest extends TestCase implements TimingControllerAware {
 * ...
 *
 *   public void myVolumeTest(int size) {
 *
 *    timingUtils = this.getTimingController();
 *
 *    boolean stopNow = false;
 *
 *    // In Sender thread.
 *      for(int i = 0; !stopNow && i < size; i++)
 *        // Send request i.
 *        ...
 *
 *    // In Receiver thread.
 *    onReceive(Object o) {
 *      try {
 *      // Check o is as expected.
 *      if (....)
 *      {
 *        if (timingUtils != null)
 *          timingUtils.completeTest(true);
 *      }
 *      else
 *      {
 *        if (timingUtils != null)
 *          timingUtils.completeTest(false);
 *      }
 *      } catch (InterruptedException e) {
 *        stopNow = true;
 *        return;
 *      }
 *    }
 * 
 *
 * 
 * CRC Card Responsibilities
 * 
 Allow test timers to be suspended, restarted or reset.
 * 
 Allow tests to register multiple pass/fails and timings.
 * 
 *
 * @author Rupert Smith
 */
public interface TimingController
{
    /**
     * Gets the timing controller associated with the current test thread. Tests that use timing controller should
     * always get the timing controller from this method in the same thread that called the setUp, tearDown or test
     * method. The controller returned by this method may be called from any thread because it remembers the thread id
     * of the original test thread.
     *
     * @return The timing controller associated with the current test thread.
     */
    TimingController getControllerForCurrentThread();

    /**
     * Suspends the test timer.
     *
     * @return The current time in nanoseconds.
     */
    long suspend();

    /**
     * Allows the test timer to continue running after a suspend.
     *
     * @return The current time in nanoseconds.
     */
    long resume();

    /**
     * Completely restarts the test timer from zero.
     *
     * @return The current time in nanoseconds.
     */
    long restart();

    /**
     * Register an additional pass/fail for the current test. The test result is assumed to apply to a test of 'size'
     * parmeter 1. Use the {@link #completeTest(boolean, int)} method to register timings with parameters.
     *
     * @param  testPassed Whether or not this timing is for a test pass or fail.
     *
     * @throws InterruptedException If the test runner decides that testing should stop it throws this exception to
     *                              indicate to the test method that it should stop immediately.
     */
    void completeTest(boolean testPassed) throws InterruptedException;

    /**
     * Register an additional pass/fail for the current test. The test result is applies to a test of the specified
     * 'size' parmeter.
     *
     * @param  testPassed Whether or not this timing is for a test pass or fail.
     * @param  param      The test parameter size for parameterized tests.
     *
     * @throws InterruptedException If the test runner decides that testing should stop it throws this exception to
     *                              indicate to the test method that it should stop immediately.
     */
    void completeTest(boolean testPassed, int param) throws InterruptedException;

    /**
     * Register an additional pass/fail for the current test. The test result is applies to a test of the specified
     * 'size' parmeter and allows the caller to sepecify the timing to log.
     *
     * @param  testPassed Whether or not this timing is for a test pass or fail.
     * @param  param      The test parameter size for parameterized tests.
     * @param  timeNanos  The time in nano seconds to log the test result with.
     *
     * @throws InterruptedException If the test runner decides that testing should stop it throws this exception to
     *                              indicate to the test method that it should stop immediately.
     */
    void completeTest(boolean testPassed, int param, long timeNanos) throws InterruptedException;
}