jBehave Tutorial

This extends the previous tutorials

• BDD with jBehave
• jBehave with jUnit 

To appreciate jBehave, let's look at a better example here. This example is about a science formula

  Speed = distance / Time.

So,

• given  distance and time, calculate speed
• given speed and time, calculate distance
• given speed and distance, calculate time.

Step 1: The story file in plain english. speed.story under src/main/resources/jBehave folder.

Narrative: As a student, I want to practice speed formula where speed = distance / time

scenario: calculate speed from distance and time

Given distance = 10.0
Given time = 2.5
When calculate speed
Then verify speed = 4.0


scenario: calculate distance from speed and time

Given speed = 4.0
Given time = 2.5
When calculate distance
Then verify distance = 10.00

scenario: calculate time from speed and distance

Given speed = 4.0
Given distance = 10.0
When calculate time
Then verify time = 2.50

Step 2: Mapping the story to Java step class. The steps are fine grained so that they can be mixed and matched depending on th scenario.

package com.mycompany.jbehave2;

import org.jbehave.core.annotations.Given;
import org.jbehave.core.annotations.Named;
import org.jbehave.core.annotations.Then;
import org.jbehave.core.annotations.When;
import org.jbehave.core.steps.Steps;
import org.springframework.util.Assert;

public class SpeedVelocityFormulaSteps extends Steps
{
    
    SpeedVelocityFormaula svf = new SpeedVelocityFormulaImpl();
    
    private double speed;
    private double distance;
    private double time;
    
    private double resultSpeed;
    private double resultDistance;
    private double resultTime;
    
    @Given("speed = $speed")
    public void speedInput(@Named("speed") double speed)
    {
        this.speed = speed;
    }
    
    @Given("distance = $distance")
    public void distanceInput(@Named("distance") double distance)
    {
        this.distance = distance;
    }
    
    @Given("time = $time")
    public void timeInput(@Named("time") double time)
    {
        this.time = time;
    }
    
    @When("calculate speed")
    public void calcSpeed()
    {
        Assert.notNull(distance);
        Assert.notNull(time);
        
        resultSpeed = svf.calculateSpeed(this.distance, this.time);
    }
    
    @When("calculate distance")
    public void calcDistance()
    {
        Assert.notNull(speed);
        Assert.notNull(time);
        
        resultDistance = svf.calculateDistance(this.speed, this.time);
    }
    
    @When("calculate time")
    public void calcTime()
    {
        Assert.notNull(speed);
        Assert.notNull(distance);
        
        resultTime = svf.calculateTime(this.speed, this.distance);
    }
    
    @Then("verify speed = $speedSupplied")
    public void verifySpeed(double speedSupplied)
    {
        Assert.notNull(distance);
        Assert.notNull(time);
        
        junit.framework.Assert.assertEquals(speedSupplied, resultSpeed);
    }
    
    @Then("verify distance = $distanceSupplied")
    public void verifyDistance(double distanceSupplied)
    {
        Assert.notNull(this.speed);
        Assert.notNull(time);
        
        junit.framework.Assert.assertEquals(distanceSupplied, resultDistance);
    }
    
    @Then("verify time = $timeSupplied")
    public void verifyTime(double timeSupplied)
    {
        Assert.notNull(speed);
        Assert.notNull(distance);
        
        junit.framework.Assert.assertEquals(timeSupplied, resultTime);
    }
    
}

Step 3: The actual interface that performs the calculations.

package com.mycompany.jbehave2;

public interface SpeedVelocityFormaula
{
    abstract double calculateSpeed(double distance, double time);
    
    abstract double calculateDistance(double speed, double time);
    
    abstract double calculateTime(double speed, double distance);
}

Step 4: The implementation. This is the class under test.

package com.mycompany.jbehave2;

public class SpeedVelocityFormulaImpl implements SpeedVelocityFormaula
{  
    public double calculateSpeed(double distance, double time)
    {
        return distance / time; // s = d/t
    }
    
    public double calculateDistance(double speed, double time)
    {
        return speed * time; //speed * time
    }
    
    public double calculateTime(double speed, double distance)
    {
        return distance / speed;  //distance/speed
    }
    
}

Step 5: Finally the jUnit test class

package com.mycompany.jbehave2;

import de.codecentric.jbehave.junit.monitoring.JUnitReportingRunner;

import java.util.Arrays;
import java.util.List;

import org.jbehave.core.junit.JUnitStories;
import org.jbehave.core.steps.InjectableStepsFactory;
import org.jbehave.core.steps.InstanceStepsFactory;
import org.junit.runner.RunWith;

@RunWith(JUnitReportingRunner.class)
public class JBehaveUnitTest extends JUnitStories
{
    
    public JBehaveUnitTest()
    {
        super();
    }
    
    public InjectableStepsFactory stepsFactory()
    {
        return new InstanceStepsFactory(configuration(), new SpeedVelocityFormulaSteps());
    }
    
    @Override
    protected List<String> storyPaths()
    {
        return Arrays.asList("jbehave/speed.story");
    }
    
}

Step 6: Run th unit test.