Improve your tests using Kotlin.

Transcript

1. Improve your tests using Kotlin Fábio Carballo @fabiocarballo
2. Why Kotlin?…
3. • Immutability first
4. • Immutability first • Hides Nullability
5. • Immutability first • Hides Nullability • Allows extensions to third-party classes
6. • Immutability first • Hides Nullability • Allows extensions to third-party classes • High-order functions / Lambdas
7. Still afraid?… Use Kotlin in your tests.
8. • Mockito testCompile 'org.mockito:mockito-core:2.8.9' • Kotlin JUnit Assertions testCompile org.jetbrains.kotlin:kotlin-test-junit:${kotlinVersion}
9. class Greeter( private val user: User) { fun getEnglishGreeting() = "Hello, ${user.fullName()}!" } class User( private val firstName: String, private val lastName: String) { fun fullName(): String = "$firstName $lastName" }
10. class GreeterTest { @Mock lateinit var user: User lateinit var tested: Greeter @Before fun setUp() { MockitoAnnotations.initMocks(this) tested = Greeter(user) } @Test fun englishGreetIsCorrect() { Mockito.`when`(user.fullName()).thenReturn("Fábio Carballo") assertEquals("Hello, Fábio Carballo!", tested.getEnglishGreeting()) } }
11. class GreeterTest { @Mock lateinit var user: User lateinit var tested: Greeter @Before fun setUp() { MockitoAnnotations.initMocks(this) tested = Greeter(user) } @Test fun englishGreetIsCorrect() { Mockito.`when`(user.fullName()).thenReturn("Fábio Carballo") assertEquals("Hello, Fábio Carballo!", tested.getEnglishGreeting()) } } org.mockito.exceptions.base.MockitoException: Cannot mock/spy class fabiocarballo.com.myapplication.User Mockito cannot mock/spy because : - final class
12. • Use Interfaces interface User { fun fullName(): String }
13. • “Open” Classes open class User( private val firstName: String, private val lastName: String) { open fun fullName(): String = "$firstName $lastName" }
14. • Use Mockito 2.2.X
15. Mockito.verify(user).addFriend(Mockito.any()) class User( private val firstName: String, private val lastName: String) { fun addFriend(friend: User) { … } }
16. Mockito.verify(user).addFriend(Mockito.any()) class User( private val firstName: String, private val lastName: String) { fun addFriend(friend: User) { … } } Mockito Matchers rely on null-values.
17. Mockito.verify(user).addFriend(Mockito.any()) class User( private val firstName: String, private val lastName: String) { fun addFriend(friend: User) { … } } Mockito Matchers rely on null-values. Mockito.verify(user).addFriend(null)
18. mockito-kotlin https://github.com/nhaarman/mockito-kotlin
19. mockito-kotlin verify(user).addFriend(any()) anyOrNull() anyVarArg() anyArray()
20. mockito-kotlin Mockito.`when`(user.fullName()).thenReturn(“Fábio Carballo”)
21. mockito-kotlin Mockito.`when`(user.fullName()).thenReturn(“Fábio Carballo”) whenever(user.fullName()).thenReturn(“Fábio Carballo”)
22. mockito-kotlin val user: User = Mockito.mock(User::class)
23. mockito-kotlin val user: User = Mockito.mock(User::class) val user: User = mock()
24. mockito-kotlin val user: User = Mockito.mock(User::class) val user: User = mock() val user: User = mock { on { fullName() }.thenReturn(“Fábio Carballo”) }
25. class GreeterTest { @Mock lateinit var user: User lateinit var tested: Greeter @Before fun setUp() { MockitoAnnotations.initMocks(this) tested = Greeter(user) } @Test fun englishGreetIsCorrect() { Mockito.`when`(user.fullName()).thenReturn("Fábio Carballo") assertEquals("Hello, Fábio Carballo!", tested.getEnglishGreeting()) } }
26. class GreeterTest { val user: User = mock() val tested = Greeter(user) @Test fun englishGreetIsCorrect() { whenever(user.fullName()).thenReturn("Fábio Carballo") assertEquals("Hello, Fábio Carballo!", tested.getEnglishGreeting()) } }
27. class GreeterTest { val user: User = mock() val tested = Greeter(user) @Test fun englishGreetIsCorrect() { whenever(user.fullName()).thenReturn("Fábio Carballo") assertEquals("Hello, Fábio Carballo!", tested.getEnglishGreeting()) } } class GreeterTest { val user: User = mock { on { fullName() }.thenReturn("Fábio Carballo") } val tested = Greeter(user) @Test fun englishGreetIsCorrect() { assertEquals("Hello, Fábio Carballo!", tested.getEnglishGreeting()) } }
28. Kotlin Quick-Wins
29. @Test fun test_addFriend_userHasNoFriends_FriendsListShouldNotBeEmpty() { … }
30. @Test fun test_addFriend_userHasNoFriends_FriendsListShouldNotBeEmpty() { … } @Test fun `when user has no friends and a friend is added the friends list should not be empty`() { … }
31. class ServiceA { fun methodA() { … } } class ServiceB { fun methodB() { … } } class Test { fun test() { val serviceA: ServiceA = mock() val serviceB: ServiceB = mock() serviceA.methodA() serviceB.methodB() val inOrder = inOrder(serviceA, serviceB) inOrder.verify(serviceA).methodA() inOrder.verify(serviceB).methodB() } }
32. class ServiceA { fun methodA() { … } } class ServiceB { fun methodB() { … } } class Test { fun test() { val serviceA: ServiceA = mock() val serviceB: ServiceB = mock() serviceA.methodA() serviceB.methodB() val inOrder = inOrder(serviceA, serviceB) inOrder.verify(serviceA).methodA() inOrder.verify(serviceB).methodB() } }
33. class ServiceA { fun methodA() { … } } class ServiceB { fun methodB() { … } } class Test { fun test() { val serviceA: ServiceA = mock() val serviceB: ServiceB = mock() serviceA.methodA() serviceB.methodB() inOrder(serviceA, serviceB).apply { verify(serviceA).methodA() verify(serviceB).methodB() } } }
34. kluent https://github.com/MarkusAmshove/Kluent expekt https://github.com/winterbe/expekt
35. data class User( private val firstName: String, private val lastName: String, private val age: Int) { val fullName = "$firstName $lastName" val canDrink = (age >= 18) val friends: MutableList<User> = mutableListOf() fun addFriend(user: User) { if (user !in friends) { friends.add(user) user.addFriend(this) } } }
36. @Test fun `the full name is the concatenation of the first and last name`() { val user = User(firstName = "Fábio", lastName = "Carballo", age = 26) assertEquals("Fábio Carballo", user.fullName) }
37. @Test fun `the full name is the concatenation of the first and last name`() { val user = User(firstName = "Fábio", lastName = "Carballo", age = 26) assertEquals("Fábio Carballo", user.fullName) user.fullName `should equal` "Fábio Carballo” // Kluent }
38. @Test fun `the full name is the concatenation of the first and last name`() { val user = User(firstName = "Fábio", lastName = "Carballo", age = 26) assertEquals("Fábio Carballo", user.fullName) user.fullName `should equal` "Fábio Carballo” // Kluent } infix fun Any.`should equal`(theOther: Any) = assertEquals(theOther, this)
39. @Test fun `the full name is the concatenation of the first and last name`() { val user = User(firstName = "Fábio", lastName = "Carballo", age = 26) assertEquals("Fábio Carballo", user.fullName) user.fullName `should equal` "Fábio Carballo” // Kluent user.fullName.should.equal(“Fábio Carballo”) // Expect }
40. @Test fun `friends are correctly added`() { val rui = User(firstName = "Rui", lastName = "Gonçalo", age = 28) val fabio = User(firstName = "Fábio", lastName = "Carballo", age = 26) rui.addFriend(fabio) assertEquals(listOf(fabio), rui.friends) // OR assertTrue { fabio in rui.friends } }
41. @Test fun `friends are correctly added`() { val rui = User(firstName = "Rui", lastName = "Gonçalo", age = 28) val fabio = User(firstName = "Fábio", lastName = "Carballo", age = 26) rui.addFriend(fabio) assertEquals(listOf(fabio), rui.friends) // KLUENT rui.friends `should contain` fabio rui.friends `should not contain` rui }
42. @Test fun `friends are correctly added`() { val rui = User(firstName = "Rui", lastName = "Gonçalo", age = 28) val fabio = User(firstName = "Fábio", lastName = "Carballo", age = 26) rui.addFriend(fabio) assertEquals(listOf(fabio), rui.friends) // KLUENT rui.friends `should contain` fabio rui.friends `should not contain` rui // EXPEKT rui.friends.should.contain(fabio) }
43. @Test fun `friends are correctly added`() { val rui = User(firstName = "Rui", lastName = "Gonçalo", age = 28) val fabio = User(firstName = "Fábio", lastName = "Carballo", age = 26) rui.addFriend(fabio) assertEquals(listOf(fabio), rui.friends) // KLUENT rui.friends `should contain` fabio rui.friends `should not contain` rui // EXPEKT rui.friends.should.contain(fabio) fabio.friends.should.have.all.elements(rui).and.have.size(1) }
44. @Test fun `friends are correctly added`() { val rui = User(firstName = "Rui", lastName = "Gonçalo", age = 28) val fabio = User(firstName = "Fábio", lastName = "Carballo", age = 26) rui.addFriend(fabio) assertEquals(listOf(fabio), rui.friends) // KLUENT rui.friends `should contain` fabio rui.friends `should not contain` rui // EXPEKT rui.friends.should.contain(fabio) fabio.friends.should.have.all.elements(rui).and.have.size(1) expect(rui.friends).to.contain(fabio) }
45. fun drink() { if (canDrink) { System.out.println("Drinking .. ") } else { throw UnderageDrinkingException() } } class UnderageDrinkingException() : Exception("You can't drink.")
46. fun drink() { if (canDrink) { System.out.println("Drinking .. ") } else { throw UnderageDrinkingException() } } class UnderageDrinkingException() : Exception("You can't drink.") @Test(expected = UnderageDrinkingException::class) fun `an underage user can't drink`() { val ricardo = User( firstName = "Ricardo", lastName = "Trindade", age = 17) ricardo.drink() }
47. fun drink() { if (canDrink) { System.out.println("Drinking .. ") } else { throw UnderageDrinkingException() } } class UnderageDrinkingException() : Exception("You can't drink.") fun `an underage user can't drink`() { val ricardo = User( firstName = "Ricardo", lastName = "Trindade", age = 17) val ricardoDrinks = { ricardo.drink() }
 
 ricardoDrinks `should throw` UnderageDrinkingException::class }
48. fun drink() { if (canDrink) { System.out.println("Drinking .. ") } else { throw UnderageDrinkingException() } } class UnderageDrinkingException() : Exception("You can't drink.") fun `an underage user can't drink`() { val ricardo = User( firstName = "Ricardo", lastName = "Trindade", age = 17) val ricardoDrinks = { ricardo.drink() }
 
 ricardoDrinks `should throw the Exception` UnderageDrinkingException::class `with message` "You can't drink." }
49. Spek https://github.com/spekframework/spek
50. • JUnit tests have a flat structure • RSpec • TDD test framework for Kotlin
51. @RunWith(JUnitPlatform::class) class SimpleSpec : Spek({ it("should be true") { true `should be` true } })
52. Hangman •Player 1 thinks about an arbitrary word. •Other players try to guess the word by suggesting a letter. •Each wrong guess, a part of the hangman is drawn.
53. class Hangman(private val word: String) { var wrongAnswerCount = 0 fun suggestLetter(letter: Char): Boolean { … } }
54. • Feature description • describe -> it
55. @RunWith(JUnitPlatform::class) class HangmanFeatureSpec : Spek({ val game = Hangman("apple") describe("letter verification") { it("returns true when the suggestion is correct") { game.suggestLetter('a') `should equal` true } it("returns false when the suggestion is incorrect") { game.suggestLetter('f') `should equal` false } } })
56. @RunWith(JUnitPlatform::class) class HangmanFeatureSpec : Spek({ val game = Hangman("apple") describe("letter verification") { it("returns true when the suggestion is correct") { game.suggestLetter('a') `should equal` true } it("returns false when the suggestion is incorrect") { game.suggestLetter('f') `should equal` false } } })
57. • Behavior description • given -> on -> it
58. @RunWith(JUnitPlatform::class) class HangmanBehaviorSpec : Spek({ val hiddenWord = "apple" given("a new game with the hidden word being $hiddenWord:") { val game = Hangman(hiddenWord) on(“correct suggestion") { game.suggestLetter(‘a’) it("has no wrong answers") { game.wrongAnswerCount `should equal` 0 } it("shows the guessed letters") { game.dashedWord `should equal` "a----" } } } })
59. @RunWith(JUnitPlatform::class) class HangmanBehaviorSpec : Spek({ val hiddenWord = "apple" given("a new game with the hidden word being $hiddenWord:") { val game = Hangman(hiddenWord) on(“correct suggestion") { game.suggestLetter(‘a’) it("has no wrong answers") { game.wrongAnswerCount `should equal` 0 } it("shows the guessed letters") { game.dashedWord `should equal` "a----" } } } })
60. Scopes • Tests (it)
61. Scopes • Tests (it) • Group (given, describe, context, group)
62. fun SpecBody.describe(description: String, body: SpecBody.() -> Unit) { group("describe $description", body = body) } fun SpecBody.context(description: String, body: SpecBody.() -> Unit) { group("context $description", body = body) } fun SpecBody.given(description: String, body: SpecBody.() -> Unit) { group(“given $description", body = body) }
63. Scopes • Tests (it) • Group (given, describe, context, group) • Action (on)
64. Ignoring tests • Just add an X as a prefix to the scope xit("returns true when the suggestion is correct") { game.suggestLetter('a') `should equal` true }
65. Ignoring tests • Just add an X as a prefix to the scope xit("returns true when the suggestion is correct") { game.suggestLetter('a') `should equal` true }
66. Thank you. Questions?