Arquillian : An introduction

Arquillian : An introduction
Testing with real objects
Vineet Reynolds
March 2012

How does this solve our problems?

WHY ARQUILLIAN?

Test Doubles redux
How did we arrive at the current
testing landscape?

Let’s test a repository
@Stateless @Local(UserRepository.class)
public class UserJPARepository implements UserRepository {

@PersistenceContext Injected by the container.
private EntityManager em; How do we get one in our
tests?

public User create(User user) {
em.persist(user);
How do we test this?
return user;
}
...
}

Did you say Mocks?
public class MockUserRepositoryTests {
…
@Before public void injectDependencies() {
// Mock
em = mock(EntityManager.class);
userRepository = new UserJPARepository(em);
}

@Test public void testCreateUser() throws Exception {
// Setup
User user = createTestUser();

// Execute
User createdUser = userRepository.create(user);

// Verify
verify(em, times(1)).persist(user);
assertThat(createdUser, equalTo(user));
…

Seems perfect, but…
verify(em, times(1)).persist(user);

• Is brittle
• Violates DRY
• Is not a good use of a Mock

Implementations matter

TESTING WITH REAL OBJECTS

Using a real EntityManager
public class RealUserRepositoryTests {

static EntityManagerFactory emf;
EntityManager em;
UserRepository userRepository;

@BeforeClass public static void beforeClass() {
emf = Persistence.createEntityManagerFactory("jpa-examples");
}

@Before public void setup() throws Exception {
// Initialize a real EntityManager
em = emf.createEntityManager();
userRepository = new UserJPARepository(em);
em.getTransaction().begin();
}
…

Testing with a real EntityManager
@Test
public void testCreateUser() throws Exception {
// Setup
User user = createTestUser();

// Execute
User createdUser = userRepository.create(user);
em.flush();
em.clear();

// Verify
User foundUser = em.find(User.class, createdUser.getUserId());
assertThat(foundUser, equalTo(createdUser));
}

Better, but …
• Requires a separate persistence.xml
• Manual transaction management
• Flushes and clears the persistence context
manually

Bringing the test as close as possible to production

ARQUILLIAN ENTERS THE SCENE

We must walk before we run
@RunWith(Arquillian.class) // #1 Use the Arquillian test
public class GreeterTest { runner.
@Deployment // #2
public static JavaArchive createDeployment() { Assemble a micro-
return ShrinkWrap.create(JavaArchive.class) deployment
.addClass(Greeter.class)
.addAsManifestResource(EmptyAsset.INSTANCE, "beans.xml");
}
A CDI Bean.
@Inject // #3 Managed by the container.
Greeter greeter;
Injected by Arquillian.
@Test // #4
public void should_create_greeting() {
assertEquals("Hello, Earthling!", Test like you normally do.
greeter.greet("Earthling")); No mocks.
} Just the real thing.
}

@RunWith(Arquillian.class)

JUnit TestNG
>= 4.8.1 > 5.12.1

@Deployment
• Assemble test archives with ShrinkWrap
• Bundles the -
– Class/component to test
– Supporting classes
– Configuration and resource files
– Dependent libraries

Revisiting the deployment
@Deployment // #1
public static JavaArchive createDeployment() {
return ShrinkWrap.create(JavaArchive.class) // #2
.addClass(Greeter.class) // #3
.addAsManifestResource(EmptyAsset.INSTANCE,
"beans.xml"); // #4
}

1. Annotate the method with @Deployment
2. Create a new JavaArchive. This will eventually create a JAR.
3. Add our Class-Under-Test to the archive.
4. Add an empty file named beans.xml to enable CDI.

Test enrichment
• Arquillian can enrich test class instances with
dependencies.
• Supports:
– @EJB
– @Inject
– @Resource
– @PersistenceContext
– @PersistenceUnit
– @ArquillianResource
– …

Revisiting dependency injection
@Inject
Greeter greeter;

• The CDI BeanManager is used to create a
new bean instance.
• Arquillian injects the bean into the test
class instance, before running any tests.

Writing your tests
• Write assertions as you normally would
– No record-replay-verify model
– Assert as you typically do
– Use real objects in your assertions

Running your tests
• Run the tests from your IDE or from your
CI server
– Just like you would run unit tests
• Run as JUnit test - Alt+Shift+X, T
• Run as Maven goal - Alt+Shift+X, M

Let’s recap
@RunWith(Arquillian.class) // #1 Use the Arquillian test
public class GreeterTest { runner.
@Deployment // #2
public static JavaArchive createDeployment() { Assemble a micro-
return ShrinkWrap.create(JavaArchive.class) deployment
.addClass(Greeter.class)
.addAsManifestResource(EmptyAsset.INSTANCE, "beans.xml");
}
A CDI Bean.
@Inject // #3 Managed by the container.
Greeter greeter; Injected by Arquillian.
@Test // #4
public void should_create_greeting() {
assertEquals("Hello, Earthling!",
Test like you normally do.
greeter.greet("Earthling")); No mocks.
} Just the real thing.
}

Using Arquillian to test the repository

TESTING THE REPOSITORY - DEMO

The stuff that Arquillian does under the hood

WHAT DID YOU JUST SEE?

Arquillian changes the way you see tests

WHY SHOULD YOU USE IT?

Refining the tests involving a database

THE PERSISTENCE EXTENSION

ATDD/BDD with Arquillian

THE DRONE AND JBEHAVE
EXTENSIONS

Arquillian : An introduction

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