35.3 The standalone Example Application

The standalone example application demonstrates how to create an instance of the embedded enterprise bean container in a JUnit test class and call a session bean business method. Testing the business methods of an enterprise bean in a unit test allows developers to exercise the business logic of an application separately from the other application layers, such as the presentation layer, and without having to deploy the application to a Java EE server.

The standalone example has two main components: StandaloneBean, a stateless session bean, and StandaloneBeanTest, a JUnit test class that acts as a client to StandaloneBean using the embedded container.

StandaloneBean is a simple session bean exposing a local, no-interface view with a single business method, returnMessage, which returns "Greetings!" as a String:

@Stateless
public class StandaloneBean {

    private static final String message = "Greetings!";

    public String returnMessage() {
        return message;
    }
    
}

StandaloneBeanTest calls StandaloneBean.returnMessage and tests that the returned message is correct. First, an embedded container instance and initial context are created within the setUp method, which is annotated with org.junit.Before to indicate that the method should be executed before the test methods:

@Before
public void setUp() {
    ec = EJBContainer.createEJBContainer();
    ctx = ec.getContext();
}

The testReturnMessage method, annotated with org.junit.Test to indicate that the method includes a unit test, obtains a reference to StandaloneBean through the Context instance, and calls StandaloneBean.returnMessage. The result is compared with the expected result using a JUnit assertion, assertEquals. If the string returned from StandaloneBean.returnMessage is equal to "Greetings!" the test passes:

@Test
public void testReturnMessage() throws Exception {
    logger.info("Testing standalone.ejb.StandaloneBean.returnMessage()");
    StandaloneBean instance = (StandaloneBean)
            ctx.lookup("java:global/classes/StandaloneBean");
    String expResult = "Greetings!";
    String result = instance.returnMessage();
    assertEquals(expResult, result);
}

Finally, the tearDown method, annotated with org.junit.After to indicate that the method should be executed after all the unit tests have run, closes the embedded container instance:

@After
public void tearDown() {
    if (ec != null) {
        ec.close();
    }
}