MVEL is not enough to discriminate transitions

[jgabrielygalan]

Hi,

We are facing a problem regarding usage of whenMvel. We have two transitions from one state to another state, where depending on an Mvel expression we want to execute different actions. The state machine is failing with

java.lang.RuntimeException: Tansition 'initial-[Start, _NoName_, 1, EXTERNAL]->second' is conflicted with 'initial-[Start, _NoName_, 1, EXTERNAL]->second'.
    at org.squirrelframework.foundation.fsm.impl.StateImpl.verify(StateImpl.java:560)
    at org.squirrelframework.foundation.fsm.impl.StateMachineBuilderImpl.verifyStateMachineDefinition(StateMachineBuilderImpl.java:487)
    at org.squirrelframework.foundation.fsm.impl.StateMachineBuilderImpl.prepare(StateMachineBuilderImpl.java:532)
    at org.squirrelframework.foundation.fsm.impl.StateMachineBuilderImpl.newStateMachine(StateMachineBuilderImpl.java:706)
    at com.buongiorno.be3aapi.services.authflow.TestStateMachineIssues.testMvelDiscriminatesTransition (TestStateMachineIssues.java:28)

(btw, there's a typo in that exception message: 'Tansition').

This is the test case:

public class TestStateMachineIssues {
    @Test
    public void testSetDebugEnabledDoesntBreak() {
        StateMachineBuilder<AuthFlowStateMachine, String, Object, Context> builder = StateMachineBuilderFactory.create(AuthFlowStateMachine.class, String.class, Object.class, Context.class);
        builder.externalTransition().from("initial").to("second").on("Start");
        AuthFlowStateMachine stateMachine = builder.newStateMachine("initial", StateMachineConfiguration.create().enableDebugMode(true));
        stateMachine.fire("Start", new Context());
        assertEquals("second", stateMachine.getCurrentState());
    }

    @Test
    public void testMvelDiscriminatesTransitions() {
        StateMachineBuilder<AuthFlowStateMachine, String, Object, Context> builder = StateMachineBuilderFactory.create(AuthFlowStateMachine.class, String.class, Object.class, Context.class);
        TestAction action1 = new TestAction();
        TestAction action2 = new TestAction();
        builder.externalTransition().from("initial").to("second").on("Start").whenMvel("3 > 2").perform(action1);
        builder.externalTransition().from("initial").to("second").on("Start").whenMvel("3 < 2").perform(action2);
        AuthFlowStateMachine stateMachine = builder.newStateMachine("initial", StateMachineConfiguration.create().enableDebugMode(true));
        stateMachine.fire("Start", new Context());
        assertEquals("second", stateMachine.getCurrentState());
    }
}

class TestAction extends AnonymousAction<AuthFlowStateMachine, String, Object, Context> {   
@Override
public void execute(String arg0, String arg1, Object arg2, Context arg3, AuthFlowStateMachine arg4) {}
}

class Context { 
}

class AuthFlowStateMachine extends AbstractStateMachine<AuthFlowStateMachine, String, Object, Context> {    
}

So, it looks like the whenMvel expression is not enough to discriminate between both transitions.
Is there any way around this limitation?

[hekailiang]

Hi jgabrielygalan,

Yes this is a bug. I just fixed it. Now the condition will be differentiated by its name(originally was by its class name which cause cannot differentiate mvel condition), which means in order to make your test case works you need to specify mvel condition name. You can refer to the following test case. Issue39

The fix was included in 0.3.8-SNAPSHOT.

[jgabrielygalan]

Thanks, it works with the latest version.

[hekailiang]

0.3.8 is released. Thanks for reporting this issue.