Puede que hayas oído hablar de Spock, el framework basado en Groovy que te permite hacer tus tests Java más legibles y expresivos. Pero seguramente no hayas visto una comparación de código real de tests hechos en librerías de test típicas como son JUnit y Mockito y cómo se harían en Spock, algo que realmente te haga consciente de lo que ganas, y lo que pierdes, al hacer tus tests con Spock. En esta charla no solo mostraremos eso, sino que repasaremos algunas recomendaciones de buenas prácticas típicas para los tests unitarios o de integración en Java, y veremos cómo se ven afectadas al usar Spock. Cómo algunas pierden importancia y hasta sentido, y otras nuevas aparecen para reemplazarlas. Cómo ahora puedes pensar más en el qué que en el cómo, cómo todo es más sencillo. Y cómo pierdes también cosas por el camino. ¿Te atreves a cambiar la forma de hacer tus tests?

1. MADRID · NOV 18-19 · 2016
Why Using
by @andres_viedma
instead of
in your Java Tests

2. Andrés ViedmaAndrés Viedma
@andres_viedma@andres_viedma

3. 01 SPOCK?

4. A testing framework
Tests are written in
100% compatible with Java code
Runs on
http://spockframework.org/

5. A basic JUnit test
@Test
public void thatAddAPositiveNumberToZeroReturnsTheSamePositiveNumber()
throws Exception {
int positiveNumber = 23;
int zero = 0;
int result = zero + positiveNumber;
assertEquals(positiveNumber, result);
}

6. A basic Spock test
def "Add a positive number to zero returns the same positive number"() {
given:
def positiveNumber = 23
def zero = 0
when:
def result = zero + positiveNumber
then:
result == positiveNumber
}

7. A basic Spock test
def "Add a positive number to zero returns the same positive number"() {
given:
def positiveNumber = 23
def zero = 0
when:
def result = zero + positiveNumber
then:
result == positiveNumber
}

8. A basic Spock test
DSL
def "Add a positive number to zero returns the same positive number"() {
given:
def positiveNumber = 23
def zero = 0
when:
def result = zero + positiveNumber
then:
result == positiveNumber
}

9. String literals
def "Add a positive number to zero returns the same positive number"() {
(...)
}
@Test
public void thatAddAPositiveNumberToZeroReturnsTheSamePositiveNumber()
throws Exception {
(...)
}

10. String literals
def "Add a positive number to zero returns the same positive number"() {
(...)
}
@Test
public void thatAddAPositiveNumberToZeroReturnsTheSamePositiveNumber()
throws Exception {
(...)
}
def "En un lugar de la Mancha, de cuyo nombre no quiero acordarme,
no ha mucho tiempo que vivía un hidalgo de los de lanza en astillero,
adarga antigua, rocín flaco y galgo corredor. "() {
(...)
}

11. Spock Blocks
given:
def positiveNumber = 23
def zero = 0
when:
def result = zero + positiveNumber
then:
result == positiveNumber
int positiveNumber = 23;
int zero = 0;
int result = zero + positiveNumber;
assertEquals(positiveNumber, result);
Programming vs. Specification

12. Spock Blocks
given:
def positiveNumber = 23
def zero = 0
when:
def result = zero + positiveNumber
then:
result == positiveNumber
// Given
int positiveNumber = 23;
int zero = 0;
// When
int result = zero + positiveNumber;
// Then
assertEquals(positiveNumber, result);
Compilation check
Programming vs. Specification

13. Documented Spock Blocks
given: "A positive number"
def positiveNumber = 23
and: "Well... a SPECTACULAR zero"
def zero = 0
when: "The number is added to zero"
def result = zero + positiveNumber
then: "The result is the same number"
result == positiveNumber
int positiveNumber = 23;
int zero = 0;
int result = zero + positiveNumber;
assertEquals(positiveNumber, result);
Documents purpose
Helps thinking

14. expect block
given: "A positive number"
def positiveNumber = 23
expect: "That added to zero results the same number"
zero + positiveNumber == positiveNumber
Replaces when-then for simple
functional tests

15. Expectations (then / expect)
given:
def positiveNumber = 23
def zero = 0
when:
def result = zero + positiveNumber
then:
result == positiveNumber
int positiveNumber = 23;
int zero = 0;
int result = zero + positiveNumber;
assertEquals(positiveNumber, result);

16. Multiple expectations
then:
result == positiveNumber
!collection.isEmpty()
then:
result == positiveNumber
and:
!collection.isEmpty()

17. Multiple expectations
then:
result == positiveNumber
!collection.isEmpty()
then:
def expectedResult = positiveNumber
result == expectedResult
Only conditions and variable
assignments allowed
then:
result == positiveNumber
and:
!collection.isEmpty()

18. def "Crash if zero"() {
when:
object.crashIfZero(0)
then:
thrown(ZeroException)
}
@Test(expected = OperationException.class)
public void crashIfZero()
throws Exception {
object.crashIfZero(0);
}
Exception conditions

19. def "Crash if zero"() {
when:
object.crashIfZero(0)
then:
thrown(ZeroException)
}
@Test(expected = OperationException.class)
public void crashIfZero()
throws Exception {
object.crashIfZero(0);
}
def "Dont crash if not zero"() {
when:
object.crashIfZero(1)
then:
notThrown(ZeroException)
}
@Test // No exception should be thrown
public void dontCrashIfNotZero()
throws Exception {
object.crashIfZero(1);
}
Exception conditions

20. class KakaSpec extends Specification {
static final SUBSCRIPTION_ID = 27
private AuxiliarObject auxiliar
void setup() {
(...)
}
def "xxx"() {
(...)
}
}
public class XxxxxxxxxxTest {
private static final long SUBSCRIPTION_ID = 27;
private AuxiliarObject auxiliar;
@Before
public void setUp() throws Exception {
(...)
}
@Test
public void thatXxx() throws Exception {
(...)
}
}
The test class

21. Groovy syntax sugar
when:
def result = object.getRecords()
then:
result?.list == [1, 47, 23]
Optional types
Collection literals
No ; needed
== operator for equals
Safe navigation ?. operator

22. Improved error output
Condition not satisfied:
result.value == expectedResult
| | | |
| | | 12
| | false
| 10
PaymentResult(id=2,value=10)

23. 02 MOCKING

24. Mocks Creation
@Mock
private CustomerDataRegistry customerRegistry;
(...)
private PaymentsCoordinator paymentCoordinator;
@Before
public void setup() {
MockitoAnnotations.initMocks(this);
paymentCoordinator = new PaymentsCoordinator(
customerRegistry, (...));
}
CustomerDataRegistry customerRegistry = Mock()
(...)
@Subject PaymentsCoordinator paymentCoordinator =
new PaymentsCoordinator(customerRegistry, (...))

25. Mocks Creation
@Mock
private CustomerDataRegistry customerRegistry;
(...)
private PaymentsCoordinator paymentCoordinator;
@Before
public void setup() {
MockitoAnnotations.initMocks(this);
paymentCoordinator = new PaymentsCoordinator(
customerRegistry, (...));
}
CustomerDataRegistry customerRegistry = Mock()
(...)
@Subject PaymentsCoordinator paymentCoordinator =
new PaymentsCoordinator(customerRegistry, (...))

26. Mocks Creation
@Mock
private CustomerDataRegistry customerRegistry;
(...)
private PaymentsCoordinator paymentCoordinator;
@Before
public void setup() {
MockitoAnnotations.initMocks(this);
paymentCoordinator = new PaymentsCoordinator(
customerRegistry, (...));
}
CustomerDataRegistry customerRegistry = Mock()
(...)
@Subject PaymentsCoordinator paymentCoordinator =
new PaymentsCoordinator(customerRegistry, (...))

27. Responses declaration
@Test
public void testSuccessfulPaymentWithNewCreditCard() throws Exception {
when(customerRegistry.getCustomerData(SUBSCRIPTION_ID)).thenReturn(CUSTOMER_DATA);
(...)
PaymentResult result = paymentCoordinator.doPayment(paymentData);
(...)
}
def "Succesful payment with new credit card"() {
given: "A registered customer"
customerRegistry.getCustomerData(SUBSCRIPTION_ID) >> CUSTOMER_DATA
(...)
when: "A payment is requested"
def result = paymentCoordinator.doPayment(paymentData)
(...)
}

28. Interaction expectations
@Test
public void testSuccessfulPaymentWithNewCreditCard() throws Exception {
(...)
when(paymentInteractor.performPaymentInProvider(inputFields))
.thenReturn(PAYMENT_SUCCESSFUL_OUTPUT);
PaymentResult result = paymentCoordinator.doPayment(paymentData);
verify(paymentInteractor).performPaymentInProvider(inputFields)).
(...)
}
def "Succesful payment with new credit card"() {
(...)
when: "A payment is requested"
def result = paymentCoordinator.doPayment(paymentData)
then: "It is sent to the payment provider with successful result"
1 * paymentInteractor.performPaymentInProvider(inputFields) >>
PAYMENT_SUCCESSFUL_OUTPUT
(...)
}

29. Mocks and Stubs
then:
0 * _
Semantic
Lenient: default
values
Only return values
Stubs: empty objects
Stubs: no interaction
expectations
Mocks: nulls

30. Call Matching
Arguments matching
mock.method("hello")
mock.method(!"hello")
mock.method()
mock.method(_)
mock.method(*_)
mock.method(_ as String)
mock.method({ l -> l.size() > 3 })
Method matching
customerRegistry._
_
customerRegistry./searchBy.*/(…)

31. Interactions expectations matching
Parametes matching
Order
1 * subscriber.receive("hello")
0 * subscriber.receive("hello")
(1..3) * subscriber.receive("hello")
(1.._) * subscriber.receive("hello")
(_..3) * subscriber.receive("hello")
_ * subscriber.receive("hello")
then:
1 * mock1.method1(...)
and:
1 * mock2.method2(...)
then:
1 * mock3.calledAfter1And2()
Cardinality * matching constraints

32. Forget the matchers
@Test
public void testSuccessfulPaymentWithNewCreditCard() throws Exception {
(...)
ArgumentMatcher<Payment> paymentMatcher = new ArgumentMatcher<Payment>() {
public boolean matches(Object payment) {
return ((Payment) payment).getPaymentType() != null;
}
};
verify(paymentInteractor, never()).performPaymentInProvider(
paymentMatcher, anyObject(), eq(VALIDATE));
(...)
}
def "Succesful payment with new credit card"() {
(...)
then:
0 * paymentInteractor.performPaymentInProvider(
{ payment -> payment.storedCard != null }, _, VALIDATE)
(...)
}

33. 03 SOME
PRACTICAL USES

34. Property-based testing (JUnit parameterized tests)
@RunWith(Parameterized.class)
public class PaymentProcessingOfANewCompletedResponseAuthorizationHandlerTest {
public static Object[][] data() {
return new Object[][] {
{ TransactionStatus.INITIALIZED, TransactionStatus.AUTHORIZED },
{ TransactionStatus.INITIALIZED, TransactionStatus.REFUSED },
{ TransactionStatus.ACCEPTED, TransactionStatus.AUTHORIZED },
{ TransactionStatus.ACCEPTED, TransactionStatus.REFUSED }
};
}
@Parameter public TransactionStatus currentStatus;
@Parameter(value=1) public TransactionStatus responseStatus;
@Test
public void test() throws Exception {
(...)
}
}

35. Property-based testing (JUnit parameterized tests)
@RunWith(Parameterized.class)
public class PaymentProcessingOfANewCompletedResponseAuthorizationHandlerTest {
public static Object[][] data() {
return new Object[][] {
{ TransactionStatus.INITIALIZED, TransactionStatus.AUTHORIZED },
{ TransactionStatus.INITIALIZED, TransactionStatus.REFUSED },
{ TransactionStatus.ACCEPTED, TransactionStatus.AUTHORIZED },
{ TransactionStatus.ACCEPTED, TransactionStatus.REFUSED }
};
}
@Parameter public TransactionStatus currentStatus;
@Parameter(value=1) public TransactionStatus responseStatus;
@Test
public void test() throws Exception {
(...)
}
}

36. Property-based testing (JUnit parameterized tests)
@RunWith(Parameterized.class)
public class PaymentProcessingOfANewCompletedResponseAuthorizationHandlerTest {
public static Object[][] data() {
return new Object[][] {
{ TransactionStatus.INITIALIZED, TransactionStatus.AUTHORIZED },
{ TransactionStatus.INITIALIZED, TransactionStatus.REFUSED },
{ TransactionStatus.ACCEPTED, TransactionStatus.AUTHORIZED },
{ TransactionStatus.ACCEPTED, TransactionStatus.REFUSED }
};
}
@Parameter public TransactionStatus currentStatus;
@Parameter(value=1) public TransactionStatus responseStatus;
@Test
public void test() throws Exception {
(...)
}
}

37. Property-based testing (JUnit parameterized tests)
@RunWith(Parameterized.class)
public class PaymentProcessingOfANewCompletedResponseAuthorizationHandlerTest {
public static Object[][] data() {
return new Object[][] {
{ TransactionStatus.INITIALIZED, TransactionStatus.AUTHORIZED },
{ TransactionStatus.INITIALIZED, TransactionStatus.REFUSED },
{ TransactionStatus.ACCEPTED, TransactionStatus.AUTHORIZED },
{ TransactionStatus.ACCEPTED, TransactionStatus.REFUSED }
};
}
@Parameter public TransactionStatus currentStatus;
@Parameter(value=1) public TransactionStatus responseStatus;
@Test
public void test() throws Exception {
(...)
}
}

38. Property-based testing (Spock where)
@Unroll
def "Processing of a new completed response from status #currentStatus to #responseStatus"(
currentStatus, responseStatus) {
(...)
when:
def resultTransaction = authorizationHandler.processResponse(statusInfo, FROM_RETRY)
then:
(...)
where:
currentStatus | responseStatus
TransactionStatus.INITIALIZED | TransactionStatus.AUTHORIZED
TransactionStatus.INITIALIZED | TransactionStatus.REFUSED
TransactionStatus.ACCEPTED | TransactionStatus.AUTHORIZED
TransactionStatus.ACCEPTED | TransactionStatus.REFUSED
}

39. Property-based testing (Spock where)
@Unroll
def "Processing of a new completed response from status #currentStatus to #responseStatus"(
currentStatus, responseStatus) {
(...)
when:
def resultTransaction = authorizationHandler.processResponse(statusInfo, FROM_RETRY)
then:
(...)
where:
currentStatus | responseStatus
TransactionStatus.INITIALIZED | TransactionStatus.AUTHORIZED
TransactionStatus.INITIALIZED | TransactionStatus.REFUSED
TransactionStatus.ACCEPTED | TransactionStatus.AUTHORIZED
TransactionStatus.ACCEPTED | TransactionStatus.REFUSED
}

40. Config tests (multiline and String interpolation)
def "getRejectionReasonForError with invalid reason mapped"() {
given:
def yaml = """
paymentForm:
rejectionReasonMapping:
${ERROR_CODE}: '${REJECTION_REASON_INVALID}'
"""
def config = formConfig(yaml)
when:
def returnedReason = config.getRejectionReasonForError(ERROR_CODE)
then: "Returns general error"
returnedReason == PaymentRejectionReason.GENERAL_ERROR
}

41. Config tests (multiline and String interpolation)
def "getRejectionReasonForError with invalid reason mapped"() {
given:
def yaml = """
paymentForm:
rejectionReasonMapping:
${ERROR_CODE}: '${REJECTION_REASON_INVALID}'
"""
def config = formConfig(yaml)
when:
def returnedReason = config.getRejectionReasonForError(ERROR_CODE)
then: "Returns general error"
returnedReason == PaymentRejectionReason.GENERAL_ERROR
}

42. Builders?
def payment = new PaymentTransaction(
id: TRANSACTION_ID,
subscriptionId: SUBSCRIPTION_ID,
amount: AMOUNT,
lastChangeTimestamp: OLD_TIMESTAMP)
PaymentTransaction payment = new PaymentTransactionBuilder()
.id(TRANSACTION_ID)
.subscriptionId(SUBSCRIPTION_ID)
.amount(AMOUNT)
.lastChangeTimestamp(OLD_TIMESTAMP)
.build();
Default constructor with
named parameters

43. Builders?
def payment = new PaymentTransaction(
id: TRANSACTION_ID,
subscriptionId: SUBSCRIPTION_ID,
amount: AMOUNT,
lastChangeTimestamp: OLD_TIMESTAMP)
PaymentTransaction payment = new PaymentTransactionBuilder()
.id(TRANSACTION_ID)
.subscriptionId(SUBSCRIPTION_ID)
.amount(AMOUNT)
.lastChangeTimestamp(OLD_TIMESTAMP)
.build();
Default constructor with
named parameters

44. def "Process an authorized payment "() {
given: "An already authorized payment"
def authorizedPayment = paymentTransactionWith(status: TransactionStatus.AUTHORIZED)
(...)
}
private PaymentTransaction paymentTransactionWith(Map overrides) {
def attrs = [
id: TRANSACTION_ID,
subscriptionId: SUBSCRIPTION_ID,
amount: AMOUNT,
status: TransactionStatus.INITIALIZED,
lastChangeTimestamp: OLD_TIMESTAMP
] + overrides
return new PaymentTransaction(attrs)
}
Objects with default properties

45. def "Process an authorized payment "() {
given: "An already authorized payment"
def authorizedPayment = paymentTransactionWith(status: TransactionStatus.AUTHORIZED)
(...)
}
private PaymentTransaction paymentTransactionWith(Map overrides) {
def attrs = [
id: TRANSACTION_ID,
subscriptionId: SUBSCRIPTION_ID,
amount: AMOUNT,
status: TransactionStatus.INITIALIZED,
lastChangeTimestamp: OLD_TIMESTAMP
] + overrides
return new PaymentTransaction(attrs)
}
Objects with default properties

46. Private methods for readability?
PaymentTransaction transaction = givenAnAuthorizedTransaction();
paymentProcessor.processPayment(transaction, RESPONSE_DATA);
verifyTheTransactionIsTransitionedTo(ADDING_BALANCE);
verifyTheTopupIsProcessedCorrectly();

47. Private methods for readability?
given: "An already authorized transaction"
def transaction = transactionWith(status: AUTHORIZED)
transactionRegistry.getTransactionInfo(TRANSACTION_ID) >> transaction
when: "The payment is processed"
paymentProcessor.processPayment(transaction, RESPONSE_DATA)
then: "The transaction is transitioned to adding balance status"
1 * transactionRegistry.changeTransactionStatus(
TRANSACTION_ID, TransactionStatus.ADDING_BALANCE) >>
transactionWith(status: ADDING_BALANCE)
then: "The topup is processed"
1 * topupInteractor.topup(transaction, RESPONSE_DATA) >>
new PaymentStatusInfo(TRANSACTION_ID, TransactionStatus.BALANCE_ADDED)
PaymentTransaction transaction = givenAnAuthorizedTransaction();
paymentProcessor.processPayment(transaction, RESPONSE_DATA);
verifyTheTransactionIsTransitionedTo(ADDING_BALANCE);
verifyTheTopupIsProcessedCorrectly();

48. static final MERCADOPAGO_RESULT = [
status: 'approved',
status_detail: 'ok',
description: 'Tuenti (test)',
id: 999999,
authorization_code: 858,
collector_id: 5678,
statement_descriptor: 'WWW.MERCADOPAGO.COM',
card: [
last_four_digits: 1234,
expiration_year: 2016,
expiration_month: 12
],
payer: [
first_name: NAME,
last_name: LAST_NAME,
email: EMAIL,
]
]
Tests involving 3rd party APIs – Thank God for Collection
literals

49. 04 So
what...?

50. ●
Increase abstraction level
Not “programming tests” ® specify test cases
Easy + powerful
Expressivity ® test is also documentation
● Easy to run in continuous integration systems / IDEs
● Better error detection info
Advantages?

51. ● Code Refactors not so safe
● Mocks can only be created in the Spec class
Integration tests with dependency injection overrides ... more
difficult, but possible!
Disadvantages?

52. ● Code Refactors not so safe
● Mocks can only be created in the Spec class
Integration tests with dependency injection overrides ... more
difficult, but possible!
Disadvantages?
class BaseIntegrationSpecification extends TIntegrationSpecification {
@InjectOverride MercadopagoClient mercadopago = Mock()
@Inject PaymentNotificationsService paymentNotificationsServiceMock
(...)
@TIntegrationTestsModule
static class MockedBoundariesModule extends SpockMocksModule {
(...)
}
}

53. ● Code Refactors not so safe
● Mocks can only be created in the Spec class
Integration tests with dependency injection overrides ... more
difficult, but possible!
Disadvantages?
class BaseIntegrationSpecification extends TIntegrationSpecification {
@InjectOverride MercadopagoClient mercadopago = Mock()
@Inject PaymentNotificationsService paymentNotificationsServiceMock
(...)
@TIntegrationTestsModule
static class MockedBoundariesModule extends SpockMocksModule {
(...)
}
}

54. Do you dare to change?

55. Do you dare to change?

56. Andrés ViedmaAndrés Viedma
@andres_viedma@andres_viedma
Questions?