> Markdown version of [Behaviour-Driven Development](https://vaadin.com/docs/v8/testbench/bestpractices/testbench-bdd). Section index: [llms.txt](https://vaadin.com/docs/v8/testbench/llms.txt)

# <a id="testbench.bdd"></a>Behaviour-Driven Development

Behaviour-driven development (BDD) is a development methodology based on test-driven development, where development starts from writing tests for the software-to-be. BDD involves using a *ubiquitous language* to communicate between business goals - the desired behaviour - and tests to ensure that the software fulfills those goals.

The BDD process starts by collection of business requirements expressed as *user stories*, as is typical in agile methodologies. A user with a *role* requests a *feature* to gain a *benefit*.

Stories can be expressed as number of *scenarios* that describe different cases of the desired behaviour. Such a scenario can be formalized with the following three phases:

- *Given* that I have calculator open

- *When* I push calculator buttons

- *Then* the display should show the result

This kind of formalization is realized in the JBehave BDD framework for Java. The TestBench Demo includes a JBehave example, where the above scenario is written as the [following test class](https://github.com/vaadin/testbench-demo/blob/8.0/src/test/java/com/vaadin/testbenchexample/bdd/CalculatorSteps.java):

```
public class CalculatorSteps extends TestBenchTestCase {
    private WebDriver driver;
    private CalculatorPageObject calculator;

    @BeforeScenario
    public void setUpWebDriver() {
        driver = TestBench.createDriver(new FirefoxDriver());
        calculator = PageFactory.initElements(driver,
                CalculatorPageObject.class);
    }

    @AfterScenario
    public void tearDownWebDriver() {
        driver.quit();
    }

    @Given("I have the calculator open")
    public void theCalculatorIsOpen() {
        calculator.open();
    }

    @When("I push $buttons")
    public void enter(String buttons) {
        calculator.enter(buttons);
    }

    @Then("the display should show $result")
    public void displayShows(String result) {
        assertEquals(result, calculator.getResult());
    }
}
```

The demo employs the page object defined for the application UI, as described in ["The Page Object Pattern"](https://vaadin.com/docs/v8/testbench/bestpractices/testbench-maintainable.md#testbench.maintainable.pageobject).

Such scenarios are included in one or more stories, which need to be configured in a class extending JUnitStory or JUnitStories. In the example, this is done in the <https://github.com/vaadin/testbench-demo/blob/8.0/src/test/java/com/vaadin/testbenchexample/bdd/SimpleCalculation.java> class. It defines how story classes can be found dynamically by the class loader and how stories are reported.

For further documentation, please see JBehave website at [jbehave.org](https://jbehave.org/).