Olá Habr! Apresento a você a tradução do artigo "Testing Your RxSwift Code", de Shai Mishali, de raywenderlich.com .

Escrever aplicativos reativos com o RxSwift difere conceitualmente de escrever aplicativos da "maneira usual". Difere no sentido de que os objetos em seu aplicativo geralmente não terão um significado claro; em vez disso, serão representados por um fluxo de valores no eixo do tempo, conhecido como RxSwift Observable. Este artigo fornece a chave para testar o código RxSwift.

Observable- Um mecanismo poderoso que permite que você, como desenvolvedor, responda às alterações e verifique se o estado do seu aplicativo está sempre atualizado. Juntamente com todos os benefícios que ele oferece, o teste Observablenão é uma tarefa trivial como simplesmente usar o XCTAssert para valores comuns. Mas não se preocupe: este artigo o ajudará a se tornar um especialista em testar o RxSwift!

Este artigo ensinará como criar testes de unidade para Observablethreads. Você aprenderá algumas das técnicas disponíveis para testar o código RxSwift, bem como algumas dicas. Vamos começar.

Nota: Este artigo pressupõe que você já esteja familiarizado com o RxSwift e como escrever testes simples usando o XCTest.

Começando

Os aplicativos reativos têm bom desempenho quando você precisa trabalhar com alterações de conteúdo, portanto, trabalharemos exatamente com esse aplicativo.

Faça o download do projeto inicial . Você encontrará o projeto inicial deste tutorial: Raytronome é um aplicativo de metrônomo que você pode usar para praticar música. Como você pode entender, devido ao fato de os metrônomos funcionarem ao longo do tempo, você precisa ver muita lógica que pode ser testada.

Raytronome.xcworkspace. Main.storyboard. , .

. Play . (Signature) (Tempo).

UIViewController — MetronomeViewController.swift, MetronomeViewModel.swift -, .

Observable

RxSwift Observable .

, .

; . Observable , , () .

, :

• ,
• . ""

, . , MetronomeViewModel, ViewModel - .

MetronomeViewModel.swift. ViewModel , : , ( ), , , , ,

UI. :

• 4
• 4/4
• 120
• Play/Pause isPlaying
• , , .
• "" .
• .even .odd —

RxSwift, RxBlocking RxTest. .

RxBlocking

RaytronomeTests.swift.

; RxSwift, RxCocoa, RxTest RxBlocking, viewModel setUp() MetronomeViewModel

, 4. , , . RxBlocking!

RxBlocking — RxSwift, : Observable BlockingObservable, Observable , .

, — , completed error —

RxBlocking , :

• toArray(): .
• first(): .
• last(): .

, first().

RaytronomeTests:

func testNumeratorStartsAt4() throws {
  XCTAssertEqual(try viewModel.numeratorText.toBlocking().first(), "4")
  XCTAssertEqual(try viewModel.numeratorValue.toBlocking().first(), 4)
}

func testDenominatorStartsAt4() throws {
  XCTAssertEqual(try viewModel.denominatorText.toBlocking().first(), "4")
}

toBlocking() BlockingObservable, first() . XCTAssert .

, throws, RxBlocking . throws try! .

Command-U

signatureText 4/4, tempoText 120 BPM.

,

func testSignatureStartsAt4By4() throws {
  XCTAssertEqual(try viewModel.signatureText.toBlocking().first(), "4/4")
}

func testTempoStartsAt120() throws {
  XCTAssertEqual(try viewModel.tempoText.toBlocking().first(), "120 BPM")
}

RxBlocking

, RxBlocking , "" . , :

1. , , , , RxBlocking . , — — RxBlocking
2. RxBlocking . Observable , BlockingObservable .
3. , , RxBlocking , .
4. RxBlocking , .

. : Play/Pause isPlaying, (tappedPlayPause ). .

RxTest

, RxBlocking , , , .

RxTest!

RxTest RxBlocking, , , . - , — TestScheduler.

— RxSwift, , ,

RxSwift , .

: " ?"

RxTest — TestScheduler — . , Observable Observer, "" .

— .

TestScheduler. DisposeBag Disposable . viewModel :

var scheduler: TestScheduler!
var disposeBag: DisposeBag!

, setUp(), TestScheduler DisposeBag :

scheduler = TestScheduler(initialClock: 0)
disposeBag = DisposeBag()

TestScheduler initialClock, " " . DisposeBag . .

!

"" Play/Pause , isPlaying .

:

1. Observable "" tappedPlayPause.
2. Observer' isPlaying.
3. .

, !

. RxTest-:

func testTappedPlayPauseChangesIsPlaying() {
  // 1
  let isPlaying = scheduler.createObserver(Bool.self)

  // 2
  viewModel.isPlaying
    .drive(isPlaying)
    .disposed(by: disposeBag)

  // 3
  scheduler.createColdObservable([.next(10, ()),
                                  .next(20, ()),
                                  .next(30, ())])
           .bind(to: viewModel.tappedPlayPause)
           .disposed(by: disposeBag)

  // 4
  scheduler.start()

  // 5
  XCTAssertEqual(isPlaying.events, [
    .next(0, false),
    .next(10, true),
    .next(20, false),
    .next(30, true)
  ])
}

, . :

1. TestScheduler TestableObserver , Observable — Bool. Observaer — events, .
2. drive() "" viewModel.isPlaying TestableObserver. "" .
3. Observable, "" tappedPlayPause. , Observable, TestableObservable, TestScheduler "" .
4. start() .
5. XCTAssertEqual RxTest, , isPlaying , . 10, 20 30 , , 0 — isPlaying.

? : viewModel . , .

Command-u. 5 .

, 0, 10, 20 30 , .

RxTest (Date) , VirtualTimeUnit ( Int).

RxSwift — TestScheduler .

, — , , , 10 10 , . .

, TestScheduler, ?

:

func testModifyingNumeratorUpdatesNumeratorText() {
  let numerator = scheduler.createObserver(String.self)

  viewModel.numeratorText
           .drive(numerator)
           .disposed(by: disposeBag)

  scheduler.createColdObservable([.next(10, 3),
                                  .next(15, 1)])
           .bind(to: viewModel.steppedNumerator)
           .disposed(by: disposeBag)

  scheduler.start()

  XCTAssertEqual(numerator.events, [
    .next(0, "4"),
    .next(10, "3"),
    .next(15, "1")
  ])
}

func testModifyingDenominatorUpdatesNumeratorText() {
  let denominator = scheduler.createObserver(String.self)

  viewModel.denominatorText
           .drive(denominator)
           .disposed(by: disposeBag)

  // Denominator () -  2   `steppedDenominator + 1`.
  // f(1, 2, 3, 4) = 4, 8, 16, 32
  scheduler.createColdObservable([.next(10, 2),
                                  .next(15, 4),
                                  .next(20, 3),
                                  .next(25, 1)])
          .bind(to: viewModel.steppedDenominator)
          .disposed(by: disposeBag)

  scheduler.start()

  XCTAssertEqual(denominator.events, [
    .next(0, "4"),
    .next(10, "8"),
    .next(15, "32"),
    .next(20, "16"),
    .next(25, "4")
  ])
}

func testModifyingTempoUpdatesTempoText() {
  let tempo = scheduler.createObserver(String.self)

  viewModel.tempoText
           .drive(tempo)
           .disposed(by: disposeBag)

  scheduler.createColdObservable([.next(10, 75),
                                  .next(15, 90),
                                  .next(20, 180),
                                  .next(25, 60)])
           .bind(to: viewModel.tempo)
           .disposed(by: disposeBag)

  scheduler.start()

  XCTAssertEqual(tempo.events, [
    .next(0, "120 BPM"),
    .next(10, "75 BPM"),
    .next(15, "90 BPM"),
    .next(20, "180 BPM"),
    .next(25, "60 BPM")
  ])
}

:

• testModifyingNumeratorUpdatesNumeratorText: , .
• testModifyingDenominatorUpdatesNumeratorText: , .
• testModifyingTempoUpdatesTempoText: ,

, , . , 3, 1. , numeratorText "4" ( ), "3", , , "1".

, denominatorText

, BPM

Command-U, 8 . !

, !

. :

func testModifyingSignatureUpdatesSignatureText() {
  // 1
  let signature = scheduler.createObserver(String.self)

  viewModel.signatureText
           .drive(signature)
           .disposed(by: disposeBag)

  // 2
  scheduler.createColdObservable([.next(5, 3),
                                  .next(10, 1),

                                  .next(20, 5),
                                  .next(25, 7),

                                  .next(35, 12),

                                  .next(45, 24),
                                  .next(50, 32)
                                ])
           .bind(to: viewModel.steppedNumerator)
           .disposed(by: disposeBag)

  // Denominator () -  2   `steppedDenominator + 1`.
  // f(1, 2, 3, 4) = 4, 8, 16, 32
  scheduler.createColdObservable([.next(15, 2), // switch to 8ths
                                  .next(30, 3), // switch to 16ths
                                  .next(40, 4)  // switch to 32nds
                                ])
           .bind(to: viewModel.steppedDenominator)
           .disposed(by: disposeBag)

  // 3
  scheduler.start()

  // 4
  XCTAssertEqual(signature.events, [
    .next(0, "4/4"),
    .next(5, "3/4"),
    .next(10, "1/4"),

    .next(15, "1/8"),
    .next(20, "5/8"),
    .next(25, "7/8"),

    .next(30, "7/16"),
    .next(35, "12/16"),

    .next(40, "12/32"),
    .next(45, "24/32"),
    .next(50, "32/32")
  ])
}

! , , . steppedNumerator steppedDenominator , signatureText .

:

. 9 !

, .

:

1. 4/4
2. 24/32.
3. "-" ; 16/16, 8/8, , , 4/4, 24/16, 24/8 24/4 — .

: , ,

:

func testModifyingDenominatorUpdatesNumeratorValueIfExceedsMaximum() {
  // 1
  let numerator = scheduler.createObserver(Double.self)

  viewModel.numeratorValue
           .drive(numerator)
           .disposed(by: disposeBag)

  // 2

  // Denominator () -  2   `steppedDenominator + 1`.
  // f(1, 2, 3, 4) = 4, 8, 16, 32
  scheduler.createColdObservable([
      .next(5, 4), // switch to 32nds
      .next(15, 3), // switch to 16ths
      .next(20, 2), // switch to 8ths
      .next(25, 1)  // switch to 4ths
      ])
      .bind(to: viewModel.steppedDenominator)
      .disposed(by: disposeBag)

  scheduler.createColdObservable([.next(10, 24)])
           .bind(to: viewModel.steppedNumerator)
           .disposed(by: disposeBag)

  // 3
  scheduler.start()

  // 4
  XCTAssertEqual(numerator.events, [
    .next(0, 4), //  4/4
    .next(10, 24), //  24/32
    .next(15, 16), //  16/16
    .next(20, 8), //  8/8
    .next(25, 4) //  4/4
  ])
}

, , ! :

1. , TestableObserver "" numeratorValue
2. , . 32, 24 ( ). 24/32. , numeratorValue.
3. schelduer
4. numeratorValue

! Command-U:

XCTAssertEqual failed: ("[next(4.0) @ 0, next(24.0) @ 10]") is not equal to ("[next(4.0) @ 0, next(24.0) @ 10, next(16.0) @ 15, next(8.0) @ 20, next(4.0) @ 25]") -

! .

, numeratorValue 24, , 24/16 24/4. :

• , 4/8.
• , 7/8.
• . 4/4, 7/4 — !

, . :]

.

MetronomeViewModel.swift , numeratorValue:

numeratorValue = steppedNumerator
  .distinctUntilChanged()
  .asDriver(onErrorJustReturn: 0)

:

numeratorValue = steppedNumerator
  .distinctUntilChanged()
  .asDriver(onErrorJustReturn: 0)

steppedNumerator , steppedNumerator maxNumerator .

Command-U, 10 . !

viewModel. , 78%. !

: , Edit Scheme... - , , Tests, Options Code Coverage. Gather coverage for some targets Raytronome . Report Navigator

, . — .

, /, , ( )

— 32. RaytronomeTests.swift :

func testBeatBy32() {
  // 1
  viewModel = MetronomeViewModel(initialMeter: Meter(signature: "4/32"),
                                 autoplay: true,
                                 beatScheduler: scheduler)

  // 2
  let beat = scheduler.createObserver(Beat.self)
  viewModel.beat.asObservable()
    .take(8)
    .bind(to: beat)
    .disposed(by: disposeBag)

  // 3
  scheduler.start()

  XCTAssertEqual(beat.events, [])
}

. - :

1. viewModel . 4/32, , tappedPlayPause .
   . , viewModel SerialDispatchQueueScheduler , TestScheduler, , .
2. TestableObserver Beat 8 beat. 8 — , , .
3. scheduler. , , , — .

Command-U. :

XCTAssertEqual failed: ("[next(first) @ 1, next(regular) @ 2, next(regular) @ 3, next(regular) @ 4, next(first) @ 5, next(regular) @ 6, next(regular) @ 7, next(regular) @ 8, completed @ 8]") is not equal to ("[]") —

, , ? 1 8.

, - , 4/32 4/4. , .

Meter(signature: "4/32") Meter(signature: "4/4") Command-U. - - .

, ! , - , . , ? -, VirtualTimeUnit, .

120 BPM, 4 ( 4/4), 0.5 . 32, 0.0625 .

, — , TestScheduler , VirtualTimeUnit.

resolution . resolution — TestScheduler 1.

0.0625/1 1, 0.5/1 1, .

, resolution, .

viewModel, , :

scheduler = TestScheduler(initialClock: 0, resolution: 0.01)

resolution

resoulution

4/32 viewModel Command-U.

, .

XCTAssertEqual failed: ("[next(first) @ 6, next(regular) @ 12, next(regular) @ 18, next(regular) @ 24, next(first) @ 30, next(regular) @ 36, next(regular) @ 42, next(regular) @ 48, completed @ 48]") is not equal to ("[]") —

6. XCTAssertEqual :

XCTAssertEqual(beat.events, [
  .next(6, .first),
  .next(12, .regular),
  .next(18, .regular),
  .next(24, .regular),
  .next(30, .first),
  .next(36, .regular),
  .next(42, .regular),
  .next(48, .regular),
  .completed(48)
])

Command-U, , . !

- 4/4 .

:

func testBeatBy4() {
  scheduler = TestScheduler(initialClock: 0, resolution: 0.1)

  viewModel = MetronomeViewModel(initialMeter: Meter(signature: "4/4"),
                                 autoplay: true,
                                 beatScheduler: scheduler)

  let beat = scheduler.createObserver(Beat.self)
  viewModel.beat.asObservable()
    .take(8)
    .bind(to: beat)
    .disposed(by: disposeBag)

  scheduler.start()

  XCTAssertEqual(beat.events, [
    .next(5, .first),
    .next(10, .regular),
    .next(15, .regular),
    .next(20, .regular),
    .next(25, .first),
    .next(30, .regular),
    .next(35, .regular),
    .next(40, .regular),
    .completed(40)
  ])
}

— , resolution, 0.1, 4.

Command-U, , 12 !

, , 99.25% MetronomeViewModel, . : beatType.

beatType — , , , beatType .even .odd. . , , :

func testBeatTypeAlternates() {
  scheduler = TestScheduler(initialClock: 0, resolution: 0.1)

  viewModel = MetronomeViewModel(initialMeter: Meter(signature: "4/4"),
                                 autoplay: true,
                                 beatScheduler: scheduler)

  let beatType = scheduler.createObserver(BeatType.self)
  viewModel.beatType.asObservable()
    .take(8)
    .bind(to: beatType)
    .disposed(by: disposeBag)

  scheduler.start()

  XCTAssertEqual(beatType.events, [
    .next(5, .even),
    .next(10, .odd),
    .next(15, .even),
    .next(20, .odd),
    .next(25, .even),
    .next(30, .odd),
    .next(35, .even),
    .next(40, .odd),
    .completed(40)
  ])
}

?

, . , RxSwift. RxBlocking , RxTest .

, Scheduler, TestScheduler .

Muito mais pode ser aprendido no RxSwift e no RxBlocking - seu trabalho interno, operadores e assim por diante. O melhor lugar para continuar é a documentação oficial do RxSwift , bem como uma lista de operadores do RxBlocking .

Se você tiver alguma dúvida ou comentário sobre o conteúdo do artigo - seja bem-vindo aos comentários ou na discussão do artigo original . Obrigado pela leitura! Atenção , este artigo é uma tradução do artigo de raywenderlich.com .