Since developing process oriented software is no different from developing any other software, we believe that process definitions should be easily testable. This chapter shows how you can use plain JUnit without any extensions to unit test the process definitions that you author.

The development cycle should be kept as short as possible. Changes made to the sources of software should be immediately verifiable. Preferably, without any intermediate build steps. The examples given below will show you how to develop and test jBPM processes without intermediate steps.

Mostly the unit tests of process definitions are execution scenarios. Each scenario is executed in one JUnit testmethod and will feed in the external triggers (read: signals) into a process execution and verifies after each signal if the process is in the expected state.

Let's look at an example of such a test. We take a simplified version of the auction process with the following graphical representation:

Figure 19.1. The auction test process

Now, let's write a test that executes the main scenario:

public class AuctionTest extends TestCase {

  // parse the process definition
  static ProcessDefinition auctionProcess = 
      ProcessDefinition.parseParResource("org/jbpm/tdd/auction.par");

  // get the nodes for easy asserting
  static StartState start = auctionProcess.getStartState();
  static State auction = (State) auctionProcess.getNode("auction");
  static EndState end = (EndState) auctionProcess.getNode("end");

  // the process instance
  ProcessInstance processInstance;

  // the main path of execution
  Token token;

  public void setUp() {
    // create a new process instance for the given process definition
    processInstance = new ProcessInstance(auctionProcess);

    // the main path of execution is the root token
    token = processInstance.getRootToken();
  }
  
  public void testMainScenario() {
    // after process instance creation, the main path of 
    // execution is positioned in the start state.
    assertSame(start, token.getNode());
    
    token.signal();
    
    // after the signal, the main path of execution has 
    // moved to the auction state
    assertSame(auction, token.getNode());
    
    token.signal();
    
    // after the signal, the main path of execution has 
    // moved to the end state and the process has ended
    assertSame(end, token.getNode());
    assertTrue(processInstance.hasEnded());
  }
}