org.junit.rules
Class Stopwatch

java.lang.Object
  org.junit.rules.Stopwatch

All Implemented Interfaces:

TestRule

public class Stopwatch
extends Object
implements TestRule

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);
 }
 

Since:

4.12

Constructor Summary

Stopwatch()

Method Summary

Statement	apply(Statement base, Description description) Modifies the method-running Statement to implement this test-running rule.
protected void	failed(long nanos, Throwable e, Description description) Invoked when a test fails
protected void	finished(long nanos, Description description) Invoked when a test method finishes (whether passing or failing)
long	runtime(TimeUnit unit) Gets the runtime for the test.
protected void	skipped(long nanos, AssumptionViolatedException e, Description description) Invoked when a test is skipped due to a failed assumption.
protected void	succeeded(long nanos, Description description) Invoked when a test succeeds

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Stopwatch

public Stopwatch()

Method Detail

runtime

public long runtime(TimeUnit unit)

Gets the runtime for the test.

Parameters:

unit - time unit for returned runtime

Returns:

runtime measured during the test

succeeded

protected void succeeded(long nanos,
                         Description description)

Invoked when a test succeeds

failed

protected void failed(long nanos,
                      Throwable e,
                      Description description)

Invoked when a test fails

skipped

protected void skipped(long nanos,
                       AssumptionViolatedException e,
                       Description description)

Invoked when a test is skipped due to a failed assumption.

finished

protected void finished(long nanos,
                        Description description)

Invoked when a test method finishes (whether passing or failing)

apply

public final Statement apply(Statement base,
                             Description description)

Description copied from interface: TestRule

Modifies the method-running Statement to implement this test-running rule.

Specified by:

apply in interface TestRule

Parameters:

base - The Statement to be modified

description - A Description of the test implemented in base

Returns:

a new statement, which may be the same as base, a wrapper around base, or a completely new Statement.