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Chapter 15. Testing and debugging

15.1. Unit testing
15.1.1. Helper methods to create your session
15.1.2. Assertions
15.1.3. Testing integration with external services
15.1.4. Configuring persistence
15.2. Debugging
15.2.1. The Process Instances View
15.2.2. The Human Task View
15.2.3. The Audit View

Even though business processes aren't code (we even recommend you to make them as high-level as possible and to avoid adding implementation details), they also have a life cycle like other development artefacts. And since business processes can be updated dynamically, testing them (so that you don't break any use cases when doing a modification) is really important as well.

When unit testing your process, you test whether the process behaves as expected in specific use cases, for example test the output based on the existing input. To simplify unit testing, jBPM includes a helper class called JbpmJUnitTestCase (in the jbpm-bpmn2 test module) that you can use to greatly simplify your junit testing, by offering:

For example, conside the following hello world process containing a start event, a script task and an end event. The following junit test will create a new session, start the process and then verify whether the process instance completed successfully and whether these three nodes have been executed.

public class MyProcessTest extends JbpmJUnitTestCase {

   public void testProcess() {
       // create your session and load the given process(es)
       StatefulKnowledgeSession ksession = createKnowledgeSession("sample.bpmn");
       // start the process
       ProcessInstance processInstance = ksession.startProcess("com.sample.bpmn.hello");
       // check whether the process instance has completed successfully
       assertProcessInstanceCompleted(processInstance.getId(), ksession);
       // check whether the given nodes were executed during the process execution
       assertNodeTriggered(processInstance.getId(), "StartProcess", "Hello", "EndProcess");

Real-life business processes typically include the invocation of external services (like for example a human task service, an email server or your own domain-specific services). One of the advantages of our domain-specific process approach is that you can specify yourself how to actually execute your own domain-specific nodes, by registering a handler. And this handler can be different depending on your context, allowing you to use testing handlers for unit testing your process. When you are unit testing your business process, you can register test handlers that then verify whether specific services are requested correctly, and provide test responses for those services. For example, imagine you have an email node or a human task as part of your process. When unit testing, you don't want to send out an actual email but rather test whether the email that is requested contains the correct information (for example the right to email, a personalized body, etc.).

A TestWorkItemHandler is provided by default that can be registered to collect all work items (a work item represents one unit of work, like for example sending one specific email or invoking one specific service and contains all the data related to that task) for a given type. This test handler can then be queried during unit testing to check whether specific work was actually requested during the execution of the process and that the data associcated with the work was correct.

The following example describes how a process that sends out an email could be tested. This test case in particular will test whether an exception is raised when the email could not be sent (which is simulated by notifying the engine that the sending the email could not be completed). The test case uses a test handler that simply registers when an email was requested (and allows you to test the data related to the email like from, to, etc.). Once the engine has been notified the email could not be sent (using abortWorkItem(..)), the unit test verifies that the process handles this case successfully by logging this and generating an error, which aborts the process instance in this case.

public void testProcess2() {

    // create your session and load the given process(es)
    StatefulKnowledgeSession ksession = createKnowledgeSession("sample2.bpmn");
    // register a test handler for "Email"
    TestWorkItemHandler testHandler = new TestWorkItemHandler();
    ksession.getWorkItemManager().registerWorkItemHandler("Email", testHandler);
    // start the process
    ProcessInstance processInstance = ksession.startProcess("com.sample.bpmn.hello2");
    assertProcessInstanceActive(processInstance.getId(), ksession);
    assertNodeTriggered(processInstance.getId(), "StartProcess", "Email");
    // check whether the email has been requested
    WorkItem workItem = testHandler.getWorkItem();
    assertEquals("Email", workItem.getName());
    assertEquals("me@mail.com", workItem.getParameter("From"));
    assertEquals("you@mail.com", workItem.getParameter("To"));
    // notify the engine the email has been sent
    assertProcessInstanceAborted(processInstance.getId(), ksession);
    assertNodeTriggered(processInstance.getId(), "Gateway", "Failed", "Error");

This section describes how to debug processes using the Eclipse plugin. This means that the current state of your running processes can be inspected and visualized during the execution. Note that we currently don't allow you to put breakpoints on the nodes within a process directly. You can however put breakpoints inside any Java code you might have (i.e. your application code that is invoking the engine or invoked by the engine, listeners, etc.) or inside rules (that could be evaluated in the context of a process). At these breakpoints, you can then inspect the internal state of all your process instances.

When debugging the application, you can use the following debug views to track the execution of the process: