behavior-driven development with jgiven

Behavior drivendevelopment with JGivenAchim Wiedemann | 24.10.2017

24.10.2017 Achim WiedemannSeite 2

Who am I?

Achim Wiedemann

Software developer

Joined Haufe-Lexware in April 2015

Working on lexoffice


Sorry, but…

No Cloud

No Microservices

No Docker

No Big Data


Agenda

Part I – Introduction to BDD

Part II – Traditional BDD tools

Part III – BDD with JGiven


Part I – Introduction to BDD


What is Behavior Driven Development?

Method of writing software tests

• Started around 2004 by Dan North

• TDD for business functionality

Goals for tests:

• Focus on business value

• Make writing tests simple

• Use domain specific language

• Provide value for devs and business people

• Make acceptance criteria executable


BDD - where does it fit in?

Unit tests:

• Focus on technical components

• Traditional driver of TDD

Acceptance tests:

• Focus on business components

• Driver of BDD

• Usually UI or API tests

http://martinfowler.com/bliki/TestPyramid.html


Acceptance criteria

States requirements

Needs to be met for implementation to be accepted

Can be written in the form:

As a [role]

I want [feature]

so that [benefit]

Example:

As a customer,

I want to withdraw cash from an ATM,

so that I don’t have to wait in line at the bank.

Involved roles User intent Business value


Acceptance criteria – 2

Writing acceptance criteria can be hard

Don‘t fall into this trap:

As a user,


so that I can withdraw cash from an ATM

Simpler to write, but:

• Doesn‘t show the involved roles

• Doesn‘t show the business value for the user


Validating acceptance criteria with scenarios

Specify tests against acceptance criteria

Scenarios can be derived from acceptance criteria:

As a customer,


so that I don’t have to wait in line at the bank.

Derived scenario „Account is in credit“:

Given the account is in credit

And the card is valid

And the dispenser contains cash

When the customer requests cash

Then ensure the account is debited

And ensure cash is dispensed

And ensure the card is returned


Validating acceptance criteria with scenarios - 2

Use Given-When-Then form:

• Given [context]

When [events]

Then [expected outcomes]

Simple template

Easy to read

Easy to write

Central part of BDD


BDD summary

Validate against AC with Scenarios

• Use Given – When – Then form

Goals for tests:


• Make writing tests simple

• Use domain specific language

• Provide value for devs and business people

• Make acceptance criteria executable


Part II – Traditional BDD tools


JBehave

The missing part: „Make acceptance criteria executable“

• JBehave was born

Uses a *.story file for scenarios (plain text)

Scenarios are mapped to test methods (Java)

Run scenario tests like JUnit tests

View results as report (text, HTML, XML, …)


JBehave

Scenario: trader is not alerted below threshold

Given a stock of symbol STK1 and a threshold of 10.0

When the stock is traded at 5.0

Then the alert status should be OFF

Scenario: trader is alerted above threshold

Given a stock of symbol STK1 and a threshold of 10.0

When the stock is traded at 11.0

Then the alert status should be ON

public class TraderSteps { // look, Ma, I'm a POJO!!

private Stock stock;

@Given("a stock of symbol $symbol and a threshold of $threshold")

public void aStock(String symbol, double threshold) {

stock = new Stock(symbol, threshold);

}

@When("the stock is traded at $price")

public void theStockIsTradedAt(double price) {

stock.tradeAt(price);

}

@Then("the alert status should be $status")

public void theAlertStatusShouldBe(String status) {

ensureThat(stock.getStatus().name(), equalTo(status));

}

}


JBehave summary

The good:

• Plain english


• Use of domain specific language

• Business people can write scenarios

The bad:

• Plain english

• String matching

• No guidance with domain specific language

• Usually devs end up writing scenarios


Part III – BDD with JGiven


JGiven

Created in 2014 by Jan Schäfer (TNG Technology Consulting)

Main goal:

• Remove disconnect between code and plain text in BDD

JGiven:

• Write everything in Java code

• Promote code reuse

• Leverage existing tools (JUnit)

• Great reports


Scenario example: place order in shop

@Test

public void logged_in_customer_should_be_able_to_place_an_order() {

given()

.user_is_logged_in_as(USER_TEST.username, USER_TEST.password)

.and().user_is_on_catalog_page();

when()

.user_adds_item_to_cart(PRODUCT_ID_BOOK, 1)

.and().user_opens_cart_page()

.and().user_follows_shipping_address_link()

.and().user_enters_some_shipping_address()

.and().user_places_order();

then()

.user_should_be_on_order_success_page();

}Logged in customer should be able to place an order

Given user is logged in as test test

And user is on catalog page

When user adds item to cart 1 1

And user opens cart page

And user follows shipping address link

And user enters some shipping address

And user places order

Then user should be on order success page


Dissecting a scenario test

public class OrderScenarioTest extends ScenarioTest<GivenStage, WhenOnCatalogPageStage, ThenStage> {

private static final String PRODUCT_ID_BOOK = "1";

@Test


given()



when()






then()


}

}

Stepmethod

StageScenario


Scenarios

Methods in normal JUnit test classes

Derive JUnit test from ScenarioTest

• given()

• when()

• then()

Specify stages as type parameters

Use snake_case for test methods for proper casing


Scenarios - 2



@Test


given()



when()






then()


}

}

:GivenStage

:WhenOnCatalogPageStage

:ThenStage


Creating a DSL with stages

Building blocks of scenarios

Model states and actions

• States: stages

• Actions: step methods

Form DSL with a fluid interface

Given on catalog pageWhen add item to cartand view cartand order itemsand confirm orderand continue shoppingand view past ordersThen order history should not be empty


Creating a DSL with stages - 2

Derive from Stage

• and()

• with()

• but()

Fluid interface:

• Step methods which return stages

Allows sentences like:given().user_is_on_catalog_page().and().user_adds_item_to_cart("4711", 3);

public class WhenOnCatalogPageStage extends Stage<WhenOnCatalogPageStage> {

@ScenarioState

protected CatalogPage catalogPage;

public WhenOnCatalogPageStage user_adds_item_to_cart(String productId, int quantity) {

for (int i = 0; i < quantity; i++)

catalogPage.addProductToCart(productId);

return this;

}

}



public class WhenOnCatalogPageStage extends Stage<WhenOnCatalogPageStage> {

@ScenarioState

protected CatalogPage catalogPage;

@ScenarioState

protected CartPage cartPage;

@ScenarioState

protected OrderHistoryPage orderHistoryPage;

@ScenarioStage

protected WhenOnCartPageStage cartStage;

public WhenOnCatalogPageStage user_adds_item_to_cart(String productId, int quantity) {

for (int i = 0; i < quantity; i++)

catalogPage.addProductToCart(productId);

return this; // State machine: transition to same state (on catalog page)

}

public WhenOnCartPageStage user_opens_cart_page() {

cartPage.openPage();

return cartStage; // State machine: transition to different state (on cart page)

}

public void user_opnes_order_history_page() {

orderHistoryPage.openPage(); // State machine: end

}

}



Model states with stages

Model actions with step methods

Naming is key: focus on business language for your DSL



@Test


given()



when()






then()


}

}


Step methods

Actions of our DSL

Make up sentences in report

Use snake_case for correct casing in report


Sharing state

State can be shared accross stages

• Page objects

• Services

• Stages

Injection via @ScenarioState annotations

public abstract class WhenBaseStage<SELF extends WhenBaseStage<SELF>> extends Stage<SELF> {

@ScenarioState

protected LoginPage loginPage;

@ScenarioStage

protected WhenOnCatalogPageStage catalogStage;

...

public WhenOnCatalogPageStage user_logs_in_as(TestUser user) {

if (!loginPage.isUserOnPage())

loginPage.openPage();

loginPage.loginWithCredentials(user.username, user.password);

return catalogStage;

}

...

}


Sharing state - 2

State is passed from stage to stage

Initialization best in Given stage

Alternative to @ScenarioState annotations:

• @ProvidedScenarioState / @ExpectedScenarioState

public class GivenStage extends Stage<GivenStage> {

private final PageFactoryResource pageFactory = new PageFactoryResource();

@ScenarioState

private CatalogPage catalogPage;

@ScenarioState

private LoginPage loginPage;

@ScenarioState

private CartPage cartPage;

@BeforeScenario

public void setUp() {

catalogPage = pageFactory.createCatalogPage();

loginPage = pageFactory.createLoginPage();

cartPage = pageFactory.createCartPage();

}

...

}


Reports


Reports - 2

Correct casing when snake_case is used in methods

• Example: item_is_registered_in_SAP()

Scenarios can be grouped via tags

• Use custom annotations to create tags

Custom formatters for improved readability

• Step methods

• Method parameters

Formats: HTML and JSON


Tags

@IsTag(name="Critical", description="Features that are critical for the user")

@Retention(RetentionPolicy.RUNTIME)

public @interface CriticalFeature {

}

@CriticalFeature

@Test

public void added_item_appears_in_cart() {

...

}


Formatters

Improve readability with formatters

• Use $ in method names

• Custom formatters via @Format

Code:

when().user_adds_item_to_cart("4711", 3)

Generated report:

When user adds item to cart 4711 3

Code (using placeholders):

when().user_adds_item_$_to_cart_of_quantity_$("4711", 3)

Generated report (using placeholders):

When user adds item 4711 to cart of quantity 3


Formatters - 2

@Test

public void added_item_appears_in_cart() {

given()

.user_is_logged_in_as(USER_TEST);

when()

.user_adds_item_$_to_cart_of_quantity_$(PRODUCT_ID_BOOK, 1)

.and().user_opens_cart_page();

then()

.user_should_see_cart_item_count_of(1);

}


JGiven - Summary

The good:

• Simple JUnit tests

• Pure Java – no mapping from text to code

• Business focused DSL

• Developer friendly

The bad:

• Documentation quite good but could be even better

• Relatively unknown

• Business people can‘t write scenarios


DEMO

https://github.com/achwie/hystrix-demo