Unit testing tricks for Play 2.0 and Ebean

Basic Ebean model testing

When you want to execute some tests that interact with your Models, you need to use a Play FakeApplication. This is described in the Java section of the Play 2.0 documentation.

Here is how the code looks like :

As you can see, there is a lot of boilerplate code that we would like to avoid.

The easiest solution is to create a Test base class that will create de FakeApplication using a method annotated with @BeforeClass

Here is how the code could look like for the base class :

public class BaseModelTest {
  public static FakeApplication app;

  @BeforeClass
  public static void startApp() {
    app = Helpers.fakeApplication(Helpers.inMemoryDatabase());
    Helpers.start(app);
  }

  @AfterClass
  public static void stopApp() {
    Helpers.stop(app);
  }
}

You can then code your tests like this :

Database cleaning

To keep my tests really independent of each other, I systematically clean the database before each test.

One solution to achieve that is to create a new FakeApplication before each test. This can be done by replacing the @BeforeClass / @AfterClass annotations with @Before / @After and removing the static keyword in the methods’ declarations.

It will work well but unfortunately, this will have a bad impact on the execution time. It can be ok if you only have a few tests, but when the number of tests will grow, it can become problematic. It would be nice to find a more efficient solution.

To avoid creating a FakeApplication for each test, we could just execute directely some drop table and create table SQL scripts. This should be faster.

I found an easy way to do that by reusing the evolution script generated by the EbeanPlugin class. Here is how we can do this :

Now before each test, you automatically have a database cleaned very quickly !

Here is a sample app illustrating this code : https://github.com/mguillermin/play2-ebean-testing

Note that if you have disabled evolutions, you will probably have to hack a little bit more to generate the create and drop scripts directly from Ebean. This is what is done in the EbeanPlugin.onStart() method.

IDE integration

Once you’ve correctly made your tests work with the FakeApplication, you might want to launch them directly from your IDE.

Why ?

Launching all your tests is easy with the command line. But when you want to launch a specific test class or method, it’s usually easier to use directly your IDE. You can then precisely select which tests to run, launch them in debug mode,…

The problem

If you try to do this on a test that use an Ebean entity, it will fail. Here is an example of what you will get :

java.lang.IllegalStateException: Class [class play.db.ebean.Model] is 
enhanced and [class models.Company] is not - (you can not mix!!)

The problem is that your Model class is not enhanced by Ebean when you don’t launch your test from the Play console.

First solution : javaagent

Reading the Ebean reference guide , I found a way to automatically enhance your classes by using a specific javaagent.

All you have to do is to download Ebean, unzip it and then configure your IDE to add a JVM argument when launching the tests.

Here is how to do that with IntelliJ :

  • Go to the ‘Run’ / ‘Edit Configurations’ menu
  • Find the JUnit configuration under “Defaults”
  • Fill the ‘VM Options’ field with :
    -javaagent:/path/to/ebean/ebean-2.7.3-agent.jar
    

Play / Ebean / IntelliJ configuration

You can then enjoy running tests from your IDE.

Second solution : IDE plugin

If you use IntelliJ, there is an easier solution to enable enhancement automatically on your model classes. You will find in the plugin repository the Ebean weaver plugin that will do exactly what we want.

You just have to install it, restart, check the ‘Build’ / ‘Ebean weaving’ menu and that’s all.

Note that such a plugin exists also for Eclipse.

Conclusion

I hope that with these small tips and tricks, you will be able to enjoy even more discovering Play 2.0.

Développement web , , , ,

28 comments


  1. Andrew

    Thankyou so much! I’d been trying to work out an elegant solution for a few days, but haven’t done much Java SE stuff since 1.4 (just J2ME). I didn’t realise you could get so much out of annotations :D

  2. It’s also possible to use the DdlGenerator of Ebean for clean the DB
    Example = https://gist.github.com/2819920

  3. Hi Matthieu,

    Thank you for the solution for IDE integration : it works in Eclipse adding Ebean agent !

    I have another problem, perhaps you have informations or a solution … With “inMemoryDatabase()”, my unit tests do not work, I have exceptions :


    [error] Test models.ProjectTest.testCreateAndRetrieve failed: Error getting sequence nextval
    [error] at com.avaje.ebean.config.dbplatform.SequenceIdGenerator.getMoreIds(SequenceIdGenerator.java:213)
    ...
    [error] ...
    [error] Caused by: org.h2.jdbc.JdbcSQLException: Syntax error in SQL statement "SELECT PROJECT_SEQ.NEXTVAL UNION[*] SELECT PROJECT_SEQ.NEXTVAL UNION SELECT PROJECT_SEQ.NEXTVAL ...

    Any idea ?

    Xavier

  4. Nicolas DOUILLET

    Thanks a lot, very helpful !
    Eclipse Ebean plugin works fine.

  5. Aksel Gresvig (@agresvig)

    Great post! Thanks for the very helpful tips.

    Question: Did you use YAML for loading test-data for your unit tests by any chance?
    I am attempting to use test-data written in YAML for unit testing (and html template testing). However I cannot get this to work for the tests in Eclipse because YAML expects there to be getters/setters for the variables, but as you know Play! supports using just public fields and then it implicitly generates getters and setters. This won’t happen when you run a unit test from within Eclipse, and then loading the YAML template will fail..

    Thought I’d ask, because the only workaround I can think of is writing getters/setters in all my classes and I’d very much like to avoid that.

    • Matthieu

      I’ve just made a quick test of Yaml loading in IntelliJ and it seems to work even without getters/setters (although I had to specify my models class names in the Yaml file). I don’t know if it behaves differently using Eclipse.

      Here is the sample code I used : https://gist.github.com/3930185

  6. Matthieu

    An interesting solution from @bverbeken for removing the boilerplate code of the FakeApplication initialization using a JUnit Runner : http://ostia.be/blog/2012/10/20/play-2-test-runner/

  7. Aksel Gresvig (@agresvig)

    Matthieu,

    How do you get IntelliJ and Play to cooperate about the classpath? Do you have them both output to the same target dir?
    I cannot get IntelliJ to compile all play sources properly.

    And for testdata, I cannot get IntelliJ to out my Yaml file in the target dir. I have to run `play test` in order for my test-file (test/resources/testdata.yml) to be copied to the target/ dir..

  8. sergii

    This is helpful. Thanks. I had the same problems..

  9. @jeanjerome

    Thanx a lot Matthieu !
    Got the same problem on eclipse…
    Works fine now with Play 2.1 with the librairy avaje-ebeanorm-agent.jar .

  10. Uri

    Great Tutorial defenetly solved my problem
    I do have a problem though related to eclipse

    im following the play tutorial http://www.playframework.com/documentation/2.1.0/JavaGuide4

    this test simulate sending a login form with the right login parameters. when running from the console using play test i get http response 303
    but when running from eclipse, i get 400

    Any idea?

  11. Thiago Lima

    I tried to merge both approaches, https://gist.github.com/nboire/2819920 and https://gist.github.com/mguillermin/3930185, without success. Somehow, if I create a bigger YML (30+ entries) and add more @Test cases, soon or later Play/Ebeans starts to mess with INSERTs, using duplicated IDs and breaking PK constraints rules.

    Any clue why?

    Anyway, really nice post. Thank you.

  12. Lalit

    I an having a following issue when i m running YABE test in eclipse
    Class not found models.ModelTest
    java.lang.ClassNotFoundException: models.ModelTest
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.loadClass(RemoteTestRunner.java:693)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.loadClasses(RemoteTestRunner.java:429)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:452)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

    Is it some kind of classpath issue or else. Plz help me out…..

  13. Steven

    Hey Matthieu,

    thanks for the Article. I do encounter a very strage behaviour using a PostgreSQL database. The Downs are apparently not executed so I get an error, that tables already exist when it comes to the Ups. Do you (or anyone around) have an explanation for that?

    Grateful for any hint,

    Steven

  14. Jackson William

    Thank you Matthieu, I had problem with this and now my world brightened.

    Thanks a lot again.

  15. Yanick

    I had an issue when using this class where my first evolution had only one up and no downs. I fixed it by replacing these two lines :


    createDdl = upsDowns[0];
    dropDdl = upsDowns[1];

    with


    createDdl = upsDowns.length > 0 ? upsDowns[0] : "";
    dropDdl = upsDowns.length > 1 ? upsDowns[1] : "";

  16. Lei Gao

    Is there a way I can disable the DDL logging output?

  17. Margy U.

    The ebean plugin does not seem to still be in the eclipse marketplace. Can anyone give me the update URL?

  18. Kevin

    I’ve tried using the BaseModelTest, but get the following error concerning ebean data source. Have you seen this and do you have any suggestions?

    [error] Test models.TicketGroupTest.save failed: javax.persistence.PersistenceException: The default EbeanServer has not been defined? This is normally set via the ebean.datasource.default property. Otherwise it should be registered programatically via registerServer()
    [error] at com.avaje.ebean.Ebean$ServerManager.getPrimaryServer(Ebean.java:178)
    [error] at com.avaje.ebean.Ebean$ServerManager.access$300(Ebean.java:128)
    [error] at com.avaje.ebean.Ebean.save(Ebean.java:453)
    [error] at play.db.ebean.Model.save(Model.java:91)
    [error] at models.TicketGroupTest.save(TicketGroupTest.java:56)
    [error] …
    [info] models.TicketGroupTest

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  20. Anthony

    Thanks a lot mate. Works like a charm.

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