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package org.junit.rules;

import org.junit.AssumptionViolatedException;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;

import java.util.concurrent.TimeUnit;

/**
 * The Stopwatch Rule notifies one of its own protected methods of the time spent by a test.
 *
 * 

Override them to get the time in nanoseconds. For example, this class will keep logging the * time spent by each passed, failed, skipped, and finished test: * *

 * public static class StopwatchTest {
 *     private static final Logger logger = Logger.getLogger("");
 *
 *     private static void logInfo(Description description, String status, long nanos) {
 *         String testName = description.getMethodName();
 *         logger.info(String.format("Test %s %s, spent %d microseconds",
 *                                   testName, status, TimeUnit.NANOSECONDS.toMicros(nanos)));
 *     }
 *
 *     @Rule
 *     public Stopwatch stopwatch = new Stopwatch() {
 *         @Override
 *         protected void succeeded(long nanos, Description description) {
 *             logInfo(description, "succeeded", nanos);
 *         }
 *
 *         @Override
 *         protected void failed(long nanos, Throwable e, Description description) {
 *             logInfo(description, "failed", nanos);
 *         }
 *
 *         @Override
 *         protected void skipped(long nanos, AssumptionViolatedException e, Description description) {
 *             logInfo(description, "skipped", nanos);
 *         }
 *
 *         @Override
 *         protected void finished(long nanos, Description description) {
 *             logInfo(description, "finished", nanos);
 *         }
 *     };
 *
 *     @Test
 *     public void succeeds() {
 *     }
 *
 *     @Test
 *     public void fails() {
 *         fail();
 *     }
 *
 *     @Test
 *     public void skips() {
 *         assumeTrue(false);
 *     }
 * }
 * 
* * An example to assert runtime: *
 * @Test
 * public void performanceTest() throws InterruptedException {
 *     long delta = 30;
 *     Thread.sleep(300L);
 *     assertEquals(300d, stopwatch.runtime(MILLISECONDS), delta);
 *     Thread.sleep(500L);
 *     assertEquals(800d, stopwatch.runtime(MILLISECONDS), delta);
 * }
 * 
* * @author tibor17 * @since 4.12 */ public abstract class Stopwatch implements TestRule { private final Clock clock; private volatile long startNanos; private volatile long endNanos; public Stopwatch() { this(new Clock()); } Stopwatch(Clock clock) { this.clock = clock; } /** * Gets the runtime for the test. * * @param unit time unit for returned runtime * @return runtime measured during the test */ public long runtime(TimeUnit unit) { return unit.convert(getNanos(), TimeUnit.NANOSECONDS); } /** * Invoked when a test succeeds */ protected void succeeded(long nanos, Description description) { } /** * Invoked when a test fails */ protected void failed(long nanos, Throwable e, Description description) { } /** * Invoked when a test is skipped due to a failed assumption. */ protected void skipped(long nanos, AssumptionViolatedException e, Description description) { } /** * Invoked when a test method finishes (whether passing or failing) */ protected void finished(long nanos, Description description) { } private long getNanos() { if (startNanos == 0) { throw new IllegalStateException("Test has not started"); } long currentEndNanos = endNanos; // volatile read happens here if (currentEndNanos == 0) { currentEndNanos = clock.nanoTime(); } return currentEndNanos - startNanos; } private void starting() { startNanos = clock.nanoTime(); endNanos = 0; } private void stopping() { endNanos = clock.nanoTime(); } public final Statement apply(Statement base, Description description) { return new InternalWatcher().apply(base, description); } private class InternalWatcher extends TestWatcher { @Override protected void starting(Description description) { Stopwatch.this.starting(); } @Override protected void finished(Description description) { Stopwatch.this.finished(getNanos(), description); } @Override protected void succeeded(Description description) { Stopwatch.this.stopping(); Stopwatch.this.succeeded(getNanos(), description); } @Override protected void failed(Throwable e, Description description) { Stopwatch.this.stopping(); Stopwatch.this.failed(getNanos(), e, description); } @Override protected void skipped(AssumptionViolatedException e, Description description) { Stopwatch.this.stopping(); Stopwatch.this.skipped(getNanos(), e, description); } } static class Clock { public long nanoTime() { return System.nanoTime(); } } }




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