Yes... I've heard about Spock ;-) and most likely dozens of other testing frameworks which were created after JUnit started to exist. JUnit is old, it's sometimes a bit grumpy, nevertheless it is stil very concise and lightweight library. It is enough to spend 10 minutes with JUnit documentation to understand the basic elements of test, how to write an assertion and how to launch your first test. In a day to day job there are several other JUnit features which might be very handy, there are also a few curosities worth to mention. In this presentation I will try to cover most of them including: parameterized tests, theories (org.junit.experimental.theories), rules (@Rule) and common matchers. As was already said JUnit is not a newbie in a testing framework world, over the years several additional libraries were added, I will show you a few interesting once, including randomized testing, benchmarking and REST interactions testing. This presentation was developed with the support of Poznań JUG, Tricity JUG and Szczecin JUG who were hosting this lecture in the past. Discussion which we had during and after the meetings was a great aid and influenced heavily current content of this presentation. Adam Dudczak - Adam Dudczak (@maneo), software engineer in Allegro group, working with Java (and JUnit) since 2004. Currently member of Allegro search team working on a better search experience in Allegro.pl. One of the leaders of Poznań JUG (www.jug.poznan.pl) and co-organizer of GeeCON conference (geecon.org). Father and husband, occasionally blogs at dudczak.info/dry.

1. JUNIT
Beyond the basics
/AdamDudczak @maneo
Atmosphere2014,Warszawa,19-20.05.2014

2. WHO AM I?
Software Engineer in Allegro group
Workingwith Java(and JUnit) since 2004
One of the leaders of
Co-organizer of conference
Poznań JUG
GeeCON

3. WHY JUNIT?
source:wikipedia

4. THERE IS NO SPOCK...
source:http://bit.ly/R0r8Ox

5. WHY NOT?
source:http://bit.ly/1jNoT8f

6. ERRORRATE CLASS
publicclassErrorRate{
doubleerrorRate;
publicErrorRate(longnoOfItems,longnoOfErrors){
errorRate=calculateErrorRate(noOfItems,noOfErrors);
}
doublecalculateErrorRate(longnoOfItems,longnoOfErrors){
...
}
publicStringgetErrorRateAsString(){
returnString.format("%2.02f",errorRate);
}
}

7. SIMPLE ERRORRATE TEST
publicclassErrorRateTest{
@Test
publicvoidshouldCalculateErrorRate(){
//given
ErrorRateerrorRate=newErrorRate(100,10);
//when
Stringresult=errorRate.getErrorRateAsString();
//then
assertThat(result,is("0.01"));
}
}

8. SIMPLE ERRORRATE TEST
Object[][]testParameters=newObject[][]{
newObject[]{100,1,"0.01"},
newObject[]{0,0,"0.00"},
};
@Test
publicvoidshouldCalculateErrorRate1(){
for(inti=0;i>testParameters.length;i++){
ErrorRateerrorRate
=newErrorRate((Integer)testParameters[i][0],
(Integer)testParameters[i][1]);
Stringresult=errorRate.getErrorRateAsString();
assertThat(result,is((String)testParameters[i][2]));
}
}

9. LET'S BRAKE SOMETHING...
Object[][]testParameters=newObject[][]{
newObject[]{ 100,1,"0.02"},
newObject []{0,0,"0.02"},
};
Firsterror stops test
Allcases are seen as one test

10. JUNIT PARAMETRIZED
@RunWith(Parameterized.class)
publicclassErrorRateTest{
@Parameters
publicstaticCollection<Object[]>data(){
returnArrays.asList(newObject[][]{
newObject[]{100,1,"0.01"},
newObject[]{0,0,"0.00"},});
}
...

11. JUNIT PARAMETRIZED (2)
...
longtotalNumberOfItems;
longtotalNumberOfRejected;
doublefinalErrorRate;
publicErrorRateTest(longtotalNumberOfItems,
longtotalNumberOfRejected,
doublefinalErrorRate){
this.totalNumberOfItems=totalNumberOfItems;
this.totalNumberOfRejected=totalNumberOfRejected;
this.finalErrorRate=finalErrorRate;
}
...

12. JUNIT PARAMETRIZED (3)
...
@Test
publicvoidshouldCalculateErrorRate(){
//given
ErrorRateerrorRate=newErrorRate(totalNumberOfItems,
totalNumberOfRejected);
//when
Stringresult=errorRate.getErrorRateAsString();
//then
assertThat(result,is(finalErrorRate));
}
...

13. LET'S BRAKE SOMETHING...
Two independenttests
Alotof boilerplate code!
Onlyone occurance of @Parameters per class

14. JUNIT-PARAMS
Parameterised tests thatdon'tsuck
Created byPaweł Lipiński
Alotof veryinterestingideas.
https://code.google.com/p/junitparams/
<dependency>
<groupId>pl.pragmatists</groupId>
<artifactId>JUnitParams</artifactId>
<version>1.0.2</version>
<scope>test</scope>
</dependency>

15. JUNIT-PARAMS - SHOWCASE
@RunWith(JUnitParamsRunner.class)
publicclassSamples_of_Usage_Test{
@Test
@Parameters({"AAA,1","BBB,2"})
publicvoidparams_in_annotation(Stringp1,Integerp2){}
@Test
@Parameters
publicvoidparams_in_default_method(Stringp1,Integerp2){}
privateObjectparametersForParams_in_default_method()
{
return$($("AAA",1),$("BBB",2));
}

16. JUNIT-PARAMS - SHOWCASE
@Test
@Parameters(method="named2,named3")
publicvoidparams_in_multiple_methods(Stringp1,Integerp2){}
privateObjectnamed2(){return$($("AAA",1));}
privateObjectnamed3(){return$($("BBB",2));}
@Test
@Parameters(source
=ParametersProvidersTest.OneIntegerProvider.class)
publicvoidparameters_from_external_class(intinteger){}

17. JUNIT-PARAMS - SHOWCASE
@Test
@FileParameters("src/test/resources/test.csv")
publicvoidload_params_from_csv(intage,Stringname){}
@Test
@FileParameters(value="src/test/resources/test.csv",
mapper=PersonMapper.class)
publicvoidload_params_from_any_file(PersonTest.Personperson){}
@Test
@FileParameters("classpath:test.csv")
publicvoidload_params_from_classpath(intage,Stringname){}

18. JUNIT-PARAMS
More examples can be found at iSamples_of_Usage_Test.java
PersonTest.java
Similar to approach in TestNG
Testcode is clear and concise -YEAH!!

19. ORG.JUNIT.EXPERIMENTAL.THEORIES
Theoryis, in factaparameterized test
This approach is more focused on requirements than on
particular testcases
Similar to ScalaCheck (Scala) /QuickCheck (Erlang)

20. ORG.JUNIT.EXPERIMENTAL.THEORIES
Theorydescribes features of class/method and verifies them
usinggiven setof inputdata
Theoryis executed as one test
If assertion fails for anysetof inputdatawhole theoryfails
Example in ErrorRate_05_Theory_Test.java

21. RANDOMIZED UNIT TESTING
"Monkeytesting"-more randomness in your tests
http://labs.carrotsearch.com/randomizedtesting.html

22. RANDOMIZED UNIT TESTING
@Test
publicvoidrandomizedTesting(){
//Herewepicktwopositiveintegers.
//Notesuperclassutilitymethods.
inta=randomIntBetween(0,Integer.MAX_VALUE);
intb=randomIntBetween(0,Integer.MAX_VALUE);
intresult=Adder.add(a,b);
assertTrue(result+"<("+a+"or"+b+")?",
result>=a&&result>=b);
}

23. SOMETHING WENT WRONG!
@Seed("2300CE9BBBCFF4C8:573D00C2ABB4AD89")

24. @THREADLEAKING*
Randomized UnitTestinglibraryhelps to check/control
threads activity
@ThreadLeaking*annotations verfies if threads are leaking
from your tests/suite
Check outErrorRate_06_Randomized_Test.java

25. @RULE
source:http://bit.ly/1jNpE13

26. @RULE
Resuable @Before/@After... and more
Example in JunitRulesShowcaseTest
JUnithas severalbuilt-in @Rules, ex.:
ExternalResource, ExpectedException, TestName...

27. @RULE
publicstaticclassHasTempFolder{
@Rule
publicTemporaryFolderfolder=newTemporaryFolder();
@Test
publicvoidtestUsingTempFolder()throwsIOException{
FilecreatedFile=folder.newFile("myfile.txt");
FilecreatedFolder=folder.newFolder("subfolder");
//...
}
}
@Rule cannotbe applied to static fields -use @ClassRule

28. @RULE IN BETAMAX
importco.freeside.betamax.Betamax;
importco.freeside.betamax.Recorder;
importorg.junit.*;
publicclassMyTest{
@RulepublicRecorderrecorder=newRecorder();
@Betamax(tape="mytape")
@Test
publicvoidtestMethodThatAccessesExternalWebService(){
}
}

29. @RULE WITH SPRING AND WIREMOCK
@Rule
publicWireMockRulewireMockRule=newWireMockRule(8089);
//Checkouthttp://wiremock.org/
@Rule
publicTestRulecontextRule=newSpringContextRule(
newString[]{"testContext.xml"},this);
@Autowired
publicStringbar;
@Test
publicvoidtestBar()throwsException{
....
}

30. JUNIT BENCHMARKS AND TIMEOUT
publicclassMyTest{
@Rule
publicTestRulebenchmarkRun=newBenchmarkRule();
@Rule
publicTestTimeouttimeoutRule=newTestTimeout(30);
@Test
publicvoidtwentyMillis()throwsException{
Thread.sleep(20);
}
}
MyTest.twentyMillis:[measured10outof15rounds]
round:0.02[+-0.00],round.gc:0.00[+-0.00],GC.calls:0,
GC.time:0.00,time.total:0.32,
time.warmup:0.12,time.bench:0.20

31. JUNIT BENCHMARKS
Chartand persistentresults history
http://labs.carrotsearch.com/junit-benchmarks.html

32. BETTER EXCEPTION HANDLING
Example byRafał Borowiec ( )blog.codeleak.pl/
publicclassExpectedExceptionsTest{
@Rule
publicExpectedExceptionthrown=ExpectedException.none();
@Test
publicvoidverifiesTypeAndMessage(){
thrown.expect(RuntimeException.class);
thrown.expectMessage("Runtimeexceptionoccurred");
thrownewRuntimeException("Runtimeexceptionoccurred");
}
}

33. "NEW" ASSERTIONS
source:http://bit.ly/1taOW0H

34. "NEW" ASSERTIONS
assertThatand built-in Hamcrestmatchers
Readable assertions and better error handling
assertThat("thisstring",is("thisstring"));
assertThat(theBiscuit,is(equalTo(myBiscuit)));
assertThat("thisstring",containsString("is"));

35. ALTERNATIVE APPROACH - FEST/ASSERTJ
Alternative (butin factamainstream) wayof building
assertions
gives access to hundreds of assertionsAssertJ
assertThat(frodo.getName()).isEqualTo("Frodo");
assertThat(frodo).isNotEqualTo(sauron)
.isIn(fellowshipOfTheRing);
assertThat(sauron).isNotIn(fellowshipOfTheRing);

36. ORGANIZE TESTS IN @SUITE
@RunWith(Suite.class)
@SuiteClasses({
ErrorRate_01_SimpleTest.class,
ErrorRate_03_Parametrized_Test.class
})
publicclassSuiteInitializationExample{
@ClassRule
publicstaticExternalResourceresource=newExternalResource(){
@Override
protectedvoidbefore()throwsThrowable{
System.out.println("StartingtheheavyweightServer");
};
@Override
protectedvoidafter(){
System.out.println("StoppingtheheavyweightServer");
};
};
}

37. CATEGORIES/SUITES AND BUILD TOOLS
Suite is abitAnt-ish -use Categories
Categories are supported byboth andMaven Gradle
<build>
<plugins>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<configuration>
<groups>com.ex.FastTests,com.ex.RegressionTests</groups>
</configuration>
</plugin>
</plugins>
</build>

38. USE CATEGORIES ON THE @SUITE LEVEL
publicclassHeavyIntegrationTest{
@Test
@Category(HeavyWeight.class)
publicvoidshouldCalculateErrorRate(){
assumeTrue(isHeavyWeightServerRunning());
//heavestuffwithheavyWeightserverhere
}
...

39. USE CATEGORIES ON THE @SUITE LEVEL
@RunWith(Categories.class)
@IncludeCategory(HeavyWeight.class)
@SuiteClasses({
ErrorRate_01_SimpleTest.class,
HeavyIntegrationTest.class
})
publicclassSuiteWithCategories{
//categorymarkerinterface
publicinterfaceHeavyWeight{}
...

40. CODE SAMPLES
Allexamples can be found at:
https://bitbucket.org/maneo/junit-presentation/

41. THAT'S ALL FOLKS
Thank you for your attention.
adam (at) dudczak.info /@maneo