Package org.junit.rules

Class Stopwatch

java.lang.Object

org.junit.rules.Stopwatch

All Implemented Interfaces:

TestRule

public class Stopwatch
extends java.lang.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

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	Stopwatch.Clock
private class	Stopwatch.InternalWatcher

Field Summary

Fields

Modifier and Type	Field	Description
private Stopwatch.Clock	clock
private long	endNanos
private long	startNanos

Constructor Summary

Constructors

Constructor	Description
Stopwatch()
Stopwatch(Stopwatch.Clock clock)

Method Summary

Modifier and Type	Method	Description
Statement	apply(Statement base, Description description)	Modifies the method-running Statement to implement this test-running rule.
protected void	failed(long nanos, java.lang.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)
private long	getNanos()
long	runtime(java.util.concurrent.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.
private void	starting()
private void	stopping()
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

Field Detail

clock

private final Stopwatch.Clock clock

startNanos

private volatile long startNanos

endNanos

private volatile long endNanos

Constructor Detail

Stopwatch

public Stopwatch()

Stopwatch

Stopwatch(Stopwatch.Clock clock)

Method Detail

runtime

public long runtime(java.util.concurrent.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,
                      java.lang.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)

getNanos

private long getNanos()

starting

private void starting()

stopping

private void stopping()

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.