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JUnit is a unit testing framework for Java, created by Erich Gamma and Kent Beck.
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 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();
}
}
}