ModelJUnit tutorial¶

The Model¶

First we implement the FsmModel interface to define our eFSM in ModelJUnit:

For every input in our model, we are going to write a ModelJUnit Action:

@Action
public void myInput() {
  // Here we should update the current state...
}

and a guard that’ll tell ModelJUnit when this action is available. The guard should be a method with the name <input>Guard and return a boolean, e.g.:

public boolean myInputGuard() {
  return /* true if the current state allows myInput, false otherwise */
}

Here is the model implemented during the tutorial

The Adapter¶

Next we implemented the adapter that allows our model to communicate with and take control of our SUT.

For each one of the @Action method in the model, we added a similarly named method in the adapter class:

class MyAdapter [
  // ...
  public void myInput() {
    // Here we execute myInput on the SUT
  }
  // ...

and, in the model, we make sure that each @Action calls the right adapter method:

class MyModel implements FsmModel {
 // ...
 @Action
 public void myInput() {
   // ...
   adapter.myInput();
 }

Here is the adapter created during the tutorial:

Implementing reset¶

One of the methods that you need to implement as part of the FsmModel interface is reset. In this method, your model is supposed to reset itself as well as reset the SUT to a known state.

In case your SUT only store data in the browser, you can simply close the browser and open a new instance. But, in case your sut has a server-side data storage (e.g. a database) you will need to reset this to a known state as well. This might mean overriding files, clearing a mysql table or running a command.

Implementing getState¶

The second method that the FsmModel interface requires you to implement is getState. This method should return an object, often a string, which uniquely identify the current state. Unlike what I did during the tutorial, do not include all the state variables in the returned stat, instead it should correspond to the Visible States of your model (the states in the bubbles).

Generating tests¶

Once you have implemented your model, you can use it to generate tests. In the tutorial example, tests were generated in the main method:

public static void main(String[] argv) {
    MyModel model = new MyModel();
    //Tester tester = new LookaheadTester(model);
    RandomTester tester = new RandomTester(model);
    //Tester tester = new AllRoundTester(model);
    //Tester tester = new GreedyTester(model);
    tester.buildGraph();
    tester.addListener(new VerboseListener());
    tester.addListener(new StopOnFailureListener());
    tester.addCoverageMetric(new TransitionCoverage());
    tester.addCoverageMetric(new StateCoverage());
    tester.addCoverageMetric(new ActionCoverage());
    tester.generate(20);
    tester.printCoverage();
}

First, we need to instantiate your model:

MyModel model = new MyModel();

Then, we choose the test strategy. ModelJUnit offers four different strategies: AllRoundTester, GreedyTester, LookaheadTester and RandomTester:

RandomTester tester = new RandomTester(model);

Next we tell the tester to try and build the graph from the model implementation. This will basically generate a lot of tests until ModelJUnit thinks it has seen all the states. It’ll be used later to compute the coverage metrics. (Hint: if you want the graph building to go faster, you can write your model so that it is possible to connect the adapter after you have run buildGraph):

tester.buildGraph();

Then, we tell ModelJUnit to collect some information about the test run:

tester.addListener(new VerboseListener());
tester.addCoverageMetric(new TransitionCoverage());
tester.addCoverageMetric(new StateCoverage());
tester.addCoverageMetric(new ActionCoverage());

tester.addCoverageMetric(new StateCoverage() {
    @Override
    public String getName() {
        return "Total state coverage";
    }
});

This tells ModelJUnit to stop the test on the first failure:

tester.addListener(new StopOnFailureListener());

Final, we generate a test sequence with a given length and print the collected metrics:

tester.generate(20);
tester.printCoverage();

Usage with IntelliJ¶

There are some quirks to using ModelJUnit in IntelliJ, one way of integrating is found here:

• IntelliJ ModelJUnit