BDD DEVit

Transcript

1. Behavior Driven
   Development
   Paweł Dudek
   

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3. Behavior Driven
   Development
   

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4. What is a unit test?
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5. A method by which individual units of
   source code, sets of one or more program
   modules together with associated control
   data, usage procedures, and operating
   procedures are tested to determine if they
   are fit for use.
   --Kolawa, Adam; Huizinga, Dorota (2007)
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6. Um, what?
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7. A method by which individual units of
   source code, sets of one or more program
   modules together with associated control
   data, usage procedures, and operating
   procedures are tested to determine if they
   are fit for use.
   --Kolawa, Adam; Huizinga, Dorota (2007)
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8. What is an app?
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9. An app is a set of
   behaviors created by a
   programmer and
   expected by the user.
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10. We, humans, have a
    limited cognition.
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11. We can’t always ‘load’
    all of the code of our
    app into our memory.
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12. This means that we
    can, by accident,
    change the behavior of
    the app.
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13. Preserving behavior of
    software systems is
    hard.
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14. Enter unit tests.
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15. Unit test is a failsafe
    to make sure app
    behavior is preserved.
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16. Test Driven
    Development
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17. Tests drive the way you
    code
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18. Always write test first
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19. Tests influence
    architecture of your
    app
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20. Tests tell you whether
    your design became
    too complex
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21. There is no such thing
    as untestable behavior
    Only untestable code
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22. Have to simulate
    behavior of your
    dependency
    dependency
    dependency?
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23. Need to fake seven
    objects?
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24. Need to call five
    functions to simulate
    a behavior?
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25. Hard to specify clear
    requirements?
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26. Overcomplicated
    design
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27. Thinked-through
    design
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28. First consumer of your
    API
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29. There is no such thing
    as untestable behavior
    Only untestable code
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30. What is testable code?
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31. Testable code
    ==
    Good Architecture
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32. What is good
    architecture?
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33. SOLID
    Object-Oriented
    Design
    Sandi Metz
    https://www.youtube.com/watch?v=v-2yFMzxqwU
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34. Behavior Driven Development
    Test Driven Development
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35. What's the difference?
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36. BDD aims to improve
    certain aspects of TDD
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37. BDD tries to help you
    know what to test
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38. When writing tests
    don’t think ‘tests’
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39. Think about
    ‘behaviors’
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40. Think about examples
    how your object
    should behave
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41. Objects behavior
    ==
    Public interface
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42. You should be only testing public
    interface of your objects
    Not internal implementation
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43. Work outside-in
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44. Ubiquitous language
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45. Quick & Nimble
    Swift BDD Frameworks
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46. class DolphinSpec: QuickSpec {
    override func spec() {
    it("is friendly") {
    expect(Dolphin().isFriendly).to(beTruthy())
    }
    it("is smart") {
    expect(Dolphin().isSmart).to(beTruthy())
    }
    }
    }
    

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47. class DolphinSpec: QuickSpec {
    override func spec() {
    it("is friendly") {
    expect(Dolphin().isFriendly).to(beTruthy())
    }
    it("is smart") {
    expect(Dolphin().isSmart).to(beTruthy())
    }
    }
    }
    

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48. describe("a dolphin") {
    describe("its click") {
    it("is loud") {
    let click = Dolphin().click()
    expect(click.isLoud).to(beTruthy())
    }
    it("has a high frequency") {
    let click = Dolphin().click()
    expect(click.hasHighFrequency).to(beTruthy())
    }
    }
    }
    

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49. describe("a dolphin") {
    describe("its click") {
    it("is loud") {
    let click = Dolphin().click()
    expect(click.isLoud).to(beTruthy())
    }
    it("has a high frequency") {
    let click = Dolphin().click()
    expect(click.hasHighFrequency).to(beTruthy())
    }
    }
    }
    

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50. describe("a dolphin") {
    describe("its click") {
    it("is loud") {
    let click = Dolphin().click()
    expect(click.isLoud).to(beTruthy())
    }
    it("has a high frequency") {
    let click = Dolphin().click()
    expect(click.hasHighFrequency).to(beTruthy())
    }
    }
    }
    

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51. describe("a dolphin") {
    var dolphin: Dolphin!
    beforeEach { dolphin = Dolphin() }
    describe("its click") {
    var click: Click!
    beforeEach { click = dolphin.click() }
    it("is loud") {
    expect(click.isLoud).to(beTruthy())
    }
    it("has a high frequency") {
    expect(click.hasHighFrequency).to(beTruthy())
    }
    }
    }
    

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52. describe("a dolphin") {
    var dolphin: Dolphin!
    beforeEach { dolphin = Dolphin() }
    describe("its click") {
    var click: Click!
    beforeEach { click = dolphin.click() }
    it("is loud") {
    expect(click.isLoud).to(beTruthy())
    }
    it("has a high frequency") {
    expect(click.hasHighFrequency).to(beTruthy())
    }
    }
    }
    

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53. describe("a dolphin") {
    var dolphin: Dolphin!
    beforeEach { dolphin = Dolphin() }
    describe("its click") {
    var click: Click!
    beforeEach { click = dolphin.click() }
    it("is loud") {
    expect(click.isLoud).to(beTruthy())
    }
    it("has a high frequency") {
    expect(click.hasHighFrequency).to(beTruthy())
    }
    }
    }
    

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54. Real world example
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55. class PhotoUploadViewController: UIViewController {
    let photoUploader: PhotoUploader
    required init(photoUploader: PhotoUploader) {
    self.photoUploader = photoUploader
    super.init(nibName: nil, bundle: nil)
    navigationItem.rightBarButtonItem = UIBarButtonItem(
    title: "Done",
    target: self,
    action: #selector(PhotoUploadViewController.onTap(_:)))
    }
    @objc func onTap(_ item: UIBarButtonItem?) {
    photoUploader.upload(photo: UIImage()) { success in
    print("\(success)")
    }
    }
    }
    

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56. protocol PhotoUploader {
    func upload(photo: UIImage, completion: (_ success: Bool) -> Void)
    }
    class MockPhotoUploader: PhotoUploader {
    fileprivate(set) var photoUploadCalled: Bool = false
    func upload(photo: UIImage, completion: (_ success: Bool) -> Void) {
    self.photoUploadCalled = true
    }
    }
    

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57. var sut: PhotoUploadViewController!
    var mockPhotoUploader: MockPhotoUploader!
    beforeEach {
    mockPhotoUploader = MockPhotoUploader()
    sut = PhotoUploadViewController(photoUploader: mockPhotoUploader)
    }
    afterEach {
    sut = nil
    }
    

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58. // non-bdd
    describe("right bar button item") {
    var rightBarButtonItem: UIBarButtonItem?
    beforeEach {
    rightBarButtonItem = sut.navigationItem.rightBarButtonItem
    }
    it("should have a target") {
    let actual = rightBarButtonItem?.target as? PhotoUploadViewController
    expect(actual).to(equal(sut))
    }
    it("should have an action") {
    let expected = #selector(PhotoUploadViewController.onTap(_:))
    expect(rightBarButtonItem?.action).to(equal(expected))
    }
    }
    

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59. // non-bdd
    describe("right bar button item action") {
    beforeEach {
    let rightBarButtonItem = sut.navigationItem.rightBarButtonItem
    sut.onTap(rightBarButtonItem)
    }
    it("should tell the photo uploader to upload photo") {
    expect(fakePhotoUploader.photoUploadCalled).to(beTruthy())
    }
    }
    

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60. // bdd
    describe("right bar button item") {
    var rightBarButtonItem: UIBarButtonItem?
    beforeEach {
    rightBarButtonItem = sut.navigationItem.rightBarButtonItem
    }
    describe("when it is tapped") {
    beforeEach {
    rightBarButtonItem?.specSimulateTap()
    }
    it("should tell the photo uploader to upload photo") {
    expect(fakePhotoUploader.photoUploadCalled).to(beTruthy())
    }
    }
    }
    

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61. BDD - recap
    » Tests influence your architecture
    » No such thing as untestable behavior
    » Think examples/behaviors, not tests
    » Don’t test implementation, work outside-in
    » Use ubiquitous language to make examples easily
    understandable
    61
    

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62. Further read:
    » https://speakerdeck.com/paweldudek/bdd-devit
    » https://github.com/paweldudek/good-tdd-stuff
    » https://github.com/paweldudek/bdd-presentation
    Getting in touch:
    » @eldudi
    » pawel@dudek.mobi
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