Saturday, August 30, 2008

Database Testing with Spring 2.5 and DBUnit

We’ve been using DB Unit on our Java projects for years and the mechanics of how it’s used has evolved over time. I’ve recently spent some time making it work a little nicer for how we typically write database tests. What I’ve created makes using DBUnit on a project that is already using Spring and the testing support added in Spring 2.5 just a little easier through the application of convention and annotations.

In general, we’ve adopted the convention of loading data off the classpath from a flat dataset file named after the test located next to the test on the classpath. For example (in the maven standard directory structure):

  • src/test/java/com/acme/ - Java Test Code
  • src/test/resources/com/acme/TripRepositoryTest.xml - DB Unit Data Set for TripRepositoryTest

For most tests, the data set is loaded inside the test’s transaction and rolled back when the test completes so that nothing needs to be cleaned up (see Spring’s reference). For other tests — service or integration tests — the data is loaded outside of a transaction and must be cleared out manually. Most projects have a mix of both strategies and both should be easily supported.

When Spring 2.5 came out with its new testing framework, I threw together a custom TestExecutionListener that looks for test methods that are annotated with @DataSet, and when found, loads the data using DB Unit. Here’s a transaction-per-test example: - Example transaction-per-test Test Case
@ContextConfiguration(locations = {"classpath:applicationContext.xml"})
public class TripRepositoryImplTest extends AbstractTransactionalDataSetTestCase {
    @Autowired TripRepository repository;   @Test
    public void forIdShouldFindTrip() throws Exception {
        Trip trip = repository.forId(2);
        assertThat(trip, not(nullValue()));

The high-level execution path for this example looks like:

  1. Inject dependencies (DependencyInjectionTestExecutionListener)
  2. Start transaction (TransactionalTestExecutionListener)
  3. Load dbunit data set from TripRepositoryImplTest.xml (DataSetTestExecutionListener) using the setup operation (default is CLEAN_INSERT)
  4. Execute test
  5. Optionally cleanup dbunit data using the tear down operation (default is NONE)
  6. Rollback transaction (TransactionalTestExecutionListener)

Here’s the trimmed down log output for this test:

INFO: Began transaction (1): transaction manager; rollback [true] (
INFO: Loading dataset from location 'classpath:/eg/domain/TripRepositoryImplTest.xml' using operation 'CLEAN_INSERT'. (
INFO: Tearing down dataset using operation 'NONE', leaving database connection open. (
INFO: Rolled back transaction after test execution for test context (

For this to work in its current incarnation, a single datasource must be available for lookup in the application context. One of the interesting details is what to do with the connection used to load the data. The framework assumes that if it’s a transactional connection it should be left open because whatever started the transaction should do the closing. When it’s non-transactional it’s closed after the dataset is loaded. This convention works well for how I typically write my database tests.

In addition to the @DataSet annotation, we must add the DataSetTestExecutionListener to the set of listeners that are applied to the test class. As in the above example, you can extend AbstractTransactionalDataSetTestCase which does this for you or you can specify the listener using the class-level annotation @TestExecutionListeners (see example). It’s important that the listener is triggered after the TransactionalTestExecutionListener.

If all test methods use the dataset, then the test class (or super class) can be annotated and every test will load the dataset. Also, if a different dataset should be loaded, the name of the resource can be specified in the annotation (e.g. @DataSet(”TripRepositoryImplTest-foo.xml”) or @DataSet(”classpath:/db/trips.xml”)). Lastly, the setup and teardown database operations can be overriden (e.g. @DataSet(setupOperation = “INSERT”, teardownOperation=”DELETE”)).

This functionality is part of the C5 Test Support package and is available in our maven repository. To use it, first add the C5 Public Maven repository to your pom.xml, and then add the necessary dependencies:

    </dependency>   <dependency>

Check out the sample application for details. It’s mavenized and utilizes an in-memory database. Just check it out of subversion, look over the code, and give it a run using your IDE or from the command-line (mvn install). I’d be psyched to hear what you think and of course, welcome comments and suggestions.


By Carbon Five Community

1 comment:

Tomas Drencak said...

Hi, have you ever tried Unitils ( I think it does the same and many more...