Package org.junit.rules

Class 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

    • Constructor Summary

      Constructors 
      Constructor Description
      Stopwatch()  

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      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)
      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.
      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

    • 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

      • 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.