Property-based testing with SwiftCheck/PBT-with-SwiftCheck

Property-based testing with SwiftCheck

Transcript

1. Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
   iOS Test Night #5
   2017/07/26(Wed)
   

   ࡉপ༞հ@DeNA
   1SPQFSUZCBTFEUFTUJOH
   XJUI4XJGU$IFDL
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2. ˙:VTVLF)PTPOVNBʢ!UPCJʣ
   • ॴଐ
   ⁃ %F/"48&5άϧʔϓςετج൫νʔϜ
   • ܦྺ
   ⁃ J04ΤϯδχΞ⾣೥݄ʹ%F/"48&5άϧʔϓʹ+PJO
   • ීஈͷۀ຿
   ⁃ όʔδϣϯɾΞοϓࣗಈݕূγεςϜʢϚεςΟϑʣͷ։ൃ
   ⁃ ΞϓϦͷςετʹ·ͭΘΔௐ͍ࠪΖ͍Ζ
   • ଞ
   ⁃ ͱ͔޷͖Ͱ͢
   ࣗݾ঺հ
   Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
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3. ࠓ೔ɺ࿩͢͜ͱ
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4. 1SPQFSUZCBTFEUFTUJOH
   4XJGU$IFDL
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5. ΞδΣϯμ
   5
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   • 1SPQFSUZCBTFEUFTUJOHͱ͸ʁ
   • 4XJGU$IFDLͱ͸ʁ
   • ۩ମྫͰݟΔ
   • ྫ
   ଍͠ࢉ
   • ྫ
   ഑ྻͷ൓స
   • ༻ޠ
   • ࣮ફతͳϢʔεέʔε
   • ·ͱΊ
   

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6. 1SPQFSUZCBTFEUFTUJOH
   ͱ͸ʁ
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7. Property-based testing ͱ͸ʁ
   7
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   • ଟ਺ͳϥϯμϜ஋Λ'8ʹࣗಈੜ੒ͤ͞ɺ
   • ςετର৅ͷੑ࣭ʢ1SPQFSUZʣΛίʔυͰఆٛ͠ɺ
   • ͦͷੑ࣭͕ഁΒΕΔ஋͕ͳ͍͔ݕূ͢Δ
   • Ϣχοτςετख๏ͷͭ
   • ؔ਺ܕݴޠ)BTLFMMͷʮ2VJDL$IFDLʯ͕ݩ
   

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8. 4XJGU$IFDL
   8
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9. 4XJGU$IFDLͱ͸ʁ
   9
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   • 2VJDL$IFDLͷ4XJGU࣮૷
   • IUUQTHJUIVCDPNUZQFMJGU4XJGU$IFDL
   • 9$5FTUʹ૊ΈࠐΊΔ
   • 4XJGU[Λ࡞͍ͬͯΔ5ZQF-JGUͷϦϙδτϦ
   • 4XJGU[ͷςετʹ΋࢖ΘΕͯΔ
   • .*5MJDFOTF
   

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10. 10
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • 1SPQFSUZCBTFEUFTUJOHͱ͸ʁ
    • 4XJGU$IFDLͱ͸ʁ
    • ۩ମྫͰݟΔ
    • ྫ
    ଍͠ࢉ
    • ྫ
    ഑ྻͷ൓స
    • ༻ޠ
    • ࣮ફతͳϢʔεέʔε
    • ·ͱΊ
    

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11. ۩ମྫͱͯ͠
    ଍͠ࢉͷςετΛߟ͑ͯΈΔ
    11
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12. 9$5FTU
    &YBNQMFCBTFEUFTUJOH
    
    12
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13. // ϓϩμΫτίʔυ
    func add(_ x: UInt, _ y: UInt) -> UInt {
    return x + y
    }
    // ςετίʔυ
    func test_add_by_assert() {
    XCTAssertEqual(add(1, 2), 3)
    }
    XCTest Ͱͷ଍͠ࢉͷςετ
    13
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    1 + 2 ͷ݁Ռ͸ 3 Ͱ͋Δ͜ͱ
    • ҰൠతͳY6OJU͕ఏڙ͍ͯ͠Δํ๏
    • 2VJDLͳͲͷ#%%ͳ'8΋ຊ࣭తʹ͸ಉ͡
    

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14. ਤઆ
    14
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    ̍ʴ̎ʹ̏
    ೖྗ஋ ೖྗ஋ ظ଴஋
    ςετର৅
    

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15. ਤઆ
    15
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    ̍ʴ̎ʹ̏
    ೖྗ஋ ೖྗ஋ ظ଴஋
    ςετର৅
    ೖྗ஋ͱظ଴஋͸ɺ
    ։ൃऀ͕໌ࣔతʹબͿඞཁ͕͋Δ
    

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16. Ͳ͏΍ͬͯೖྗ஋ΛબͿʁ
    16
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17. ςετ༻ͷೖྗ஋ΛબͿٕज़
    17
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    • ಉ஋෼ׂ๏
    • ڥք஋෼ੳ
    • ΫϥγϑΟέʔγϣϯπϦʔ
    • 1BJSXJTF๏
    • FUDʜ
    

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18. ςετ༻ͷೖྗ஋ΛબͿٕज़
    18
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • ಉ஋෼ׂ๏
    • ڥք஋෼ੳ
    • ΫϥγϑΟέʔγϣϯπϦʔ
    • 1BJSXJTF๏
    • FUDʜ
    ͲΕ΋֬཰తʹόάͷى͖΍͍͢σʔ
    λΛ༧ଌͯ͠ɺಛఆ஋ͷΈͰςετ
    

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19. 4XJGU$IFDL
    1SPQFSUZCBTFEUFTUJOH
    
    19
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20. ·ͣ଍͠ࢉͷੑ࣭Λߟ͑Δ
    20
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21. ଍͠ࢉͷੑ࣭
    21
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    • ݁߹๏ଇΛຬͨ͢
    • YZZY
    • Λճ଍ͨ͠΋ͷͱɺΛճ଍ͨ͠΋ͷ͸౳͍͠
    • YY
    • ʢͪͳΈʹʣҾ͖ࢉ͸݁߹๏ଇΛຬͨ͞ͳ͍
    • YZ㱠ZY
    

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22. ଍͠ࢉͷੑ࣭
    22
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • ݁߹๏ଇΛຬͨ͢
    • YZZY
    • Λճ଍ͨ͠΋ͷͱɺΛճ଍ͨ͠΋ͷ͸౳͍͠
    • YY
    • ʢͪͳΈʹʣҾ͖ࢉ͸݁߹ੑ͋Γ
    • YZ㱠ZY
    ͜ΕΒ͕ͲΜͳೖྗ஋ʹରͯ͠΋
    อͨΕΔ΂͖ੑ࣭Ͱ͋Δɺͱߟ͑Δ
    

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23. 4XJGU$IFDLͰॻ͍ͯΈΔ
    23
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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24. 4XJGU$IFDLͰͷ଍͠ࢉͷੑ࣭ςετ
    24
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    // ;ͭ͏ͷXCTestͱಉ͡Α͏ʹ಄ʹ`test`Λ͚ͭΔ
    func test_add_property() {
    // x + y == y + x
    property("଍͠ࢉ͸݁߹๏ଇΛຬͨ͢") <- forAll { (x: UInt, y: UInt) in
    return add(x, y) == add(y, x)
    }
    // x + 1 + 1 == x + 2
    property("1Λ2ճ଍ͨ͠ͷͱɺ2Λ1ճ଍ͨ͠΋ͷ͸౳͍͠") <- forAll { (x: UInt) in
    return add(add(x, 1), 1) == add(x, 2)
    }
    }
    

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25. 4XJGU$IFDLͰͷ଍͠ࢉͷੑ࣭ςετ
    25
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    func test_add_property() {
    // x + y == y + x
    property("଍͠ࢉ͸݁߹๏ଇΛຬͨ͢") <- forAll { (x: UInt, y: UInt) in
    return add(x, y) == add(y, x)
    }
    }
    ᶃੑ࣭ͷએݴ
    

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26. 4XJGU$IFDLͰͷ଍͠ࢉͷੑ࣭ςετ
    26
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    func test_add_property() {
    // x + y == y + x
    property("଍͠ࢉ͸݁߹๏ଇΛຬͨ͢") <- forAll { (x: UInt, y: UInt) in
    return add(x, y) == add(y, x)
    }
    }
    ᶄ೚ҙͷೖྗ஋
    

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27. 4XJGU$IFDLͰͷ଍͠ࢉͷੑ࣭ςετ
    27
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    func test_add_property() {
    // x + y == y + x
    property("଍͠ࢉ͸݁߹๏ଇΛຬͨ͢") <- forAll { (x: UInt, y: UInt) in
    return add(x, y) == add(y, x)
    }
    }
    ᶅશͯʹର͠
    

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28. 4XJGU$IFDLͰͷ଍͠ࢉͷੑ࣭ςετ
    28
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    func test_add_property() {
    // x + y == y + x
    property("଍͠ࢉ͸݁߹๏ଇΛຬͨ͢") <- forAll { (x: UInt, y: UInt) in
    return add(x, y) == add(y, x)
    }
    }
    ᶆ͜ͷ͕ࣜ੒Γཱͭ
    

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29. 4XJGU$IFDLͰͷ଍͠ࢉͷੑ࣭ςετ
    29
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    func test_add_property() {
    // x + y == y + x
    property("଍͠ࢉ͸݁߹๏ଇΛຬͨ͢") <- forAll { (x: UInt, y: UInt) in
    return add(x, y) == add(y, x)
    }
    }
    ᶃੑ࣭ͷએݴ ᶄ೚ҙͷೖྗ஋
    ᶅશͯʹର͠
    ᶆ͜ͷ͕ࣜ੒Γཱͭ
    

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30. ͜ΕΛ࣮ߦ͢Δͱʁ
    30
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31. Test Case '-[SwiftCheckSampleTests.SwiftCheckSampleTests test_add_property]' started.
    *** Passed 100 tests
    .
    *** Passed 100 tests
    .
    Test Case '-[SwiftCheckSampleTests.SwiftCheckSampleTests test_add_property]' passed (0.009 seconds).
    4XJGU$IFDLͰͷςετ͕੒ޭ
    31
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    ίϯιʔϧ
    1BTTFEUFTUT
    ݸ΋ͷϥϯμϜ஋Ͱςετ͕͞Ε͍ͯΔʂ
    

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32. ۩ମతʹͲΜͳ஋͕
    બ͹Ε͍ͯΔͷ͔ʁ
    32
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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33. ۩ମతʹબ͹Ε͍ͯͨ஋
    33
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    Test Case '-[SwiftCheckSampleTests.SwiftCheckSampleTests test_add_property]'
    started.
    x: 0, y: 0
    x: 1, y: 1
    x: 0, y: 2
    x: 3, y: 3
    x: 0, y: 0
    x: 1, y: 1
    x: 0, y: 6
    x: 4, y: 1
    …
    x: 26, y: 19
    x: 34, y: 51
    x: 40, y: 18
    x: 10, y: 13
    x: 49, y: 22
    x: 9, y: 14
    x: 31, y: 65
    x: 45, y: 15
    x: 30, y: 32
    x: 46, y: 54
    x: 65, y: 34
    x: 57, y: 41
    …
    x: 58, y: 17
    x: 67, y: 17
    x: 41, y: 93
    x: 21, y: 17
    *** Passed 100 tests
    ϥϯμϜ͚ͩΕͲɺ
    খ͞Ίͷ஋͔Βςετ͞Ε͍ͯΔ
    

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34. ͱ͜ΖͰࣦഊ͢Δͱʁ
    34
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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35. *** Failed! Proposition: x + 1 + 1 == x + 2
    Falsifiable (after 3 tests and 2 shrinks):
    1
    *** Passed 2 tests
    4XJGU$IFDLͰͷςετ͕੒ޭ
    35
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    ίϯιʔϧ
    ஋͕ʮʯͷέʔεͰɺ
    ςετ͕ύε͠ͳ͔ͬͨ͜ͱ͕ใࠂ͞Εͨ
    

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36. ࣮ࡍʹʮʯͷέʔεͰ
    ࢼͯ͠ΈΔͱɾɾɾ
    36
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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37. 9$5"TTFSU&RVBMͰݕূ
    37
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    ͔֬ʹςετ͕ࣦഊͨ͠ʂ
    func add(_ x: UInt, _ y: UInt) -> UInt {
    return x * y
    }
    ݪҼ͸ֻ͚ࢉʹͳ͍ͬͯͨҝ
    

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38. 38
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • 1SPQFSUZCBTFEUFTUJOHͱ͸ʁ
    • 4XJGU$IFDLͱ͸ʁ
    • ۩ମྫͰݟΔ
    • ྫ
    ଍͠ࢉ
    • ྫ
    ഑ྻͷ൓స
    • ༻ޠ
    • ࣮ફతͳϢʔεέʔε
    • ·ͱΊ
    

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39. ഑ྻͷ൓స
    "SSBZSFWFSTFE
    
    39
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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40. ൓స SFWFSTF
    ͷੑ࣭ͱ͸ʁ
    40
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41. ഑ྻͷ൓సͷੑ࣭ͱ͸ʁ
    41
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    ˣ൓స SFWFSTF
    
    ˣ൓స SFWFSTF
    
    ճ൓సͤ͞Δͱݩʹ໭Δʂ
    

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42. 4XJGU$IFDLͰॻ͍ͯΈΔ
    42
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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43. func test_reversed() {
    property("഑ྻͷ൓సͷ൓స͸ݩͷ഑ྻͱಉ͡")
    <- forAll { (xs: ArrayOf) in
    let ys = xs.getArray
    return ys.reversed().reversed() == ys
    }
    }
    4XJGU$IFDLͰ഑ྻͷ൓సͷςετ
    43
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    YT<5>
    ͱදݱͰ͖ͳ͍ͷ͸4XJGUͷ੍ݶɻ
    ୅ΘΓʹ"SSBZ0G5ͱ͍͏ϥούʔΛࢦఆ͠ɺ
    HFU"SSBZͰத਎ΛऔΓग़͠ɻ
    "SSBZ0G*OU
    

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44. ͜͜·Ͱͷ·ͱΊ
    44
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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45. ͜͜·Ͱͷ·ͱΊ
    45
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • 1SPQFSUZCBTFEUFTUJOH
    • ςετͱͯ͠ੑ࣭ʢQSPQFSUZʣΛఆٛ
    • '8͕܁Γฦ͠ϥϯμϜ஋ͰςετΛ࣮ߦ
    • 4XJGU$IFDL
    • 9$5FTUͱ૊Έ߹Θͤͯ࢖͑Δ
    • ࣦഊͨ͠৔߹ɺͦͷ஋Λใࠂͯ͘͠ΕΔ
    • ͦͷ஋͸Ͱ͖Δ͚ͩখ͍͞஋͕બ͹Ε͍ͯΔ
    

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46. 46
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • 1SPQFSUZCBTFEUFTUJOHͱ͸ʁ
    • 4XJGU$IFDLͱ͸ʁ
    • ۩ମྫͰݟΔ
    • ྫ
    ଍͠ࢉ
    • ྫ
    ഑ྻͷ൓స
    • ༻ޠ
    • ࣮ફతͳϢʔεέʔε
    • ·ͱΊ
    

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47. 1SPQFSUZCBTFEUFTUJOH
    Ͱͷ༻ޠ
    47
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48. "SCJUSBSZ
    48
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49. Arbitrary
    49
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    • ʮ೚ҙͷʯͱ͍ͬͨҙຯ
    • 4XJGU$IFDLͰ͸ϓϩτίϧͱͯ͠ఆٛ
    • ಛఆͷܕͷϥϯμϜ஋Λੜ੒͢Δ໾ׂ
    • 4XJGUඪ४ͷܕʹ͸σϑΥϧτ࣮૷͕ఏڙ͞ΕΔ
    • ͜Εʹ४ڌ͢Δ͜ͱͰϥϯμϜ஋͕ੜ੒Ͱ͖ΔΑ͏ʹ
    public protocol Arbitrary {
    public static var arbitrary: SwiftCheck.Gen { get }
    public static func shrink(_: Self) -> [Self]
    }
    

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50. 4ISJOLJOH
    50
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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51. Shrinking
    51
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    • ʮऩॖ͢Δʯͱ͍ͬͨҙຯ
    • ಉ͘͡"SCJUSBSZϓϩτίϧʹఆٛʢPQUJPOBMʣ
    • ΑΓখ͞ͳ஋ʹ͢Δ໾ׂ
    • ͜ΕʹΑΓࣦഊͨ͠ςετσʔλʹ͍ͭͯɺ

    ΑΓখ͞ͳࣦഊέʔεΛબग़͢Δ࢓૊Έ
    Int.shrink(10)
    // => [0, 1, 2, 5]
    String.shrink(“app")
    // => ["p", "pp", ... ,"apa", "apb"]
    

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52. Shrinking
    52
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    • ʢࣦഊʣ

    ˣTISJOL
    • ʢࣦഊʣ

    ˣTISJOL
    • ʢࣦഊʣ⾣ɹ͜ΕΛʢ࠷খͷʣࣦഊྫͱͯ͠ใࠂ

    ˣTISJOL
    • ʢ੒ޭʣ
    

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53. 53
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • 1SPQFSUZCBTFEUFTUJOHͱ͸ʁ
    • 4XJGU$IFDLͱ͸ʁ
    • ۩ମྫͰݟΔ
    • ྫ
    ଍͠ࢉ
    • ྫ
    ഑ྻͷ൓స
    • ༻ޠ
    • ࣮ફతͳϢʔεέʔε
    • ·ͱΊ
    

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54. 1SPQFSUZCBTFEUFTUJOH
    ͕༗ޮͳέʔε
    54
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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55. Property-based testing ͕༗ޮͳέʔε
    55
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • ᶃ&ODPEF%FDPEF
    • ᶄ஗͘໌֬ͳΞϧΰϦζϜWTߴ଎ͳΞϧΰϦζϜ
    • ᶅϥϯμϜੑʹج͍ͮͨΞϧΰϦζϜ
    

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56. ᶃ&ODPEF%FDPEF
    56
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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57. Encode / Decode ͷϢχοτςετ
    57
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    • ΘΓͱେม
    • ϓϩύςΟ͕ଟ͍ͱॻ͘ͷେม
    • ಉ͡ೖྗ஋Λ࢖͏ͱೖΕସ͑Λݕग़Ͱ͖ͳ͍
    • ςετΛॻ͘࿑ྗʹݟ߹͍ͬͯΔ͔ʁ
    • ϦεΫ͕ߴ͍
    • Ұݟਖ਼͘͠ಈ͍͍ͯΔΑ͏ʹΈ͑Δ
    • ͚ΕͲɺҰ෦ͷ߲໨͚͚͍ͩܽͯͨΓ
    

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58. Encode / Decode ͷੑ࣭
    58
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • &ODPEF%FDPEFͨ͠΋ͷ͸ݩͱಉ͡
    • EFDPEF FODPEF PCK
    
    PCK
    

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59. Dogߏ଄ମ
    59
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    public struct Dog: Equatable {
    let name: String
    let age: Int
    func encode() -> [String: String] {
    return [
    "name": name,
    "age": "\(age)",
    ]
    }
    static func decode(_ encoded: [String: String]) -> Dog? {
    guard
    let name = encoded["name"],
    let age = (encoded["age"].flatMap{ Int($0) }) else { return nil }
    return Dog(name: name, age: age)
    }
    }
    public func == (a: Dog, b: Dog) -> Bool {
    return a.name == b.name && a.age == b.age
    }
    

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60. Dog Λ Arbiratyϓϩτίϧʹ४ڌͤ͞Δ
    60
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    extension Dog: Arbitrary {
    public static var arbitrary: SwiftCheck.Gen {
    return Gen<(String, Int)>
    .zip(String.arbitrary, Int.arbitrary)
    .map(Dog.init)
    }
    }
    ࠓճ͸TISJOLͷ࣮૷͸ׂѪ
    ʢͳͯ͘΋ಈ͖͸͢Δʣ
    

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61. SwiftCheckͰͷςετίʔυ
    61
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    func testDogEncodeDecode() {
    property(“DogΛencodeͯ͠decodeͨ͠΋ͷ͸ɺݩͱಉ͡")
    <- forAll { (dog: Dog) in
    guard let decoded = Dog.decode(dog.encode())
    else { return false }
    return dog == decoded
    }
    } "SCJUSBSZʹ४ڌͨ͠ͷͰɺ
    ϥϯμϜ஋͕ੜ੒Ͱ͖ΔΑ͏ʹͳͬͨ
    

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62. ༷ʑͳσʔλͰςετ͞Ε͍ͯΔ
    62
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    Dog(name: "", age: 0)
    Dog(name: "O", age: 1)
    Dog(name: "d", age: 1)
    Dog(name: "ÇÆØ", age: 3)
    Dog(name: "!\\-", age: -4)
    Dog(name: "0S=ä", age: 3)
    Dog(name: "¡¨sóø", age: 1)
    Dog(name: "Ü+_ Dog(name: "fín«ÄqÙv", age: -5)
    Dog(name: "ÁZõXü:¼¢", age: -4)
    Dog(name: "Ͼâñ. øýí", age: -9)
    Dog(name: "ùÝofNÁ&S", age: 9)
    Dog(name: " aÞäÈyÚ&Á", age: -5)
    Dog(name: "_¯¼Ì6<ÙRçv", age: 3)
    Dog(name: "êð©[ý#ùTó}°Õ|É", age: 7)
    Dog(name: "KVGH<ø«zE7\'", age: 12)
    

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63. ᶄ஗͘໌֬ͳΞϧΰϦζϜ
    WT
    ߴ଎ͳΞϧΰϦζϜ
    63
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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64. ஗͘໌֬ͳΞϧΰϦζϜ vs ߴ଎ͳΞϧΰϦζϜ
    64
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • ΞϧΰϦζϜ
    • ໌֬ͳॻ͖ํΛ͢Δͱʢ͍͍ͩͨʣ஗͍
    • ߴ଎ʹ͢Δͱʢ͍͍ͩͨʣίʔυ͕ෳࡶʹͳΔ
    • ςετͷ೉͠͞
    • +BWBͷ4%,ʹؚ·ΕΔೋ෼୳ࡧ͸ɺ

    ೥ؒ΋όάʹؾ͔ͮΕͳ͔ͬͨ
    

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65. ஗͘໌֬ͳΞϧΰϦζϜ vs ߴ଎ͳΞϧΰϦζϜ
    65
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • ੑ࣭Λߟ͑Δ
    • ೖྗ஋͕ಉ͡Ͱ͋Ε͹ɺ྆ऀͷ݁Ռ͸ৗʹಉ͡
    

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66. ֊৐ΛٻΊΔίʔυ
    66
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    // ֊৐Λ࠶ؼͰٻΊΔ
    func fact(_ n: Int) -> Int {
    if n == 1 { return 1 }
    return n * fact(n - 1)
    }
    // ֊৐ΛϧʔϓͰٻΊΔ
    func factFast(_ n: Int) -> Int {
    var r = n
    var i = n - 1
    while i > 1 {
    r *= i
    i = i - 1
    }
    return r
    }
    ࠶ؼ൛͸͍͕ٙͳ͍͘Β͍ʹ໌֬ɻ͚ΕͲίʔϧ
    ελοΫͷ෼ɺύϑΥʔϚϯε͸ѱ͍
    

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67. SwiftCheckͰͷςετίʔυ
    67
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    func test_fact() {
    // 1ʙ20ͷ஋ΛબͿʢେ͖͗͢ΔͱΤϥʔʹͳΔͨΊʣ
    let gen: Gen = Gen.choose((1, 20))
    property("fact()ͱfactFast()͸ৗʹಉ݁͡ՌΛฦ͢͜ͱ")
    <- forAll(gen) { (n: Int) in
    return fact(n) == factFast(n)
    }
    }
    ໌֬ͳΞϧΰϦζϜͷ݁ՌͱҰக͍ͯ͠Ε͹ɺߴ
    ଎ͳΞϧΰϦζϜ΋ਖ਼͘͠ػೳ͍ͯ͠Δͱߟ͑Β
    ΕΔ
    DIPPTFͰ஋ͷൣғΛ੍ݶ
    

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68. ᶅϥϯμϜੑʹج͍ͮͨ
    ΞϧΰϦζϜ
    68
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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69. ϥϯμϜੑʹج͍ͮͨΞϧΰϦζϜ
    69
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • έʔε
    • μϯδϣϯϚοϓͷੜ੒
    • μΠεϩʔϧ
    • ੑ࣭Λߟ͑Δ
    • Ϛοϓ͸ඞͣΰʔϧʹͭͳ͕͍ͬͯΔ͜ͱ
    • Ϛοϓʹ౸ୡͰ͖ͳ͍෦԰͕ͳ͍͜ͱ
    • े෼ʹۉ౳ͳϥϯμϜੑ͕ಘΒΕΔ͜ͱ
    

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70. ࠓ೔ͷ·ͱΊ
    70
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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71. ·ͱΊ
    71
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    • 1SPQFSUZCBTFEUFTUJOH
    • ੑ࣭ʢQSPQFSUZʣʹண໨ͨ͠Ϣχοτςετख๏
    • ଟ਺ͳϥϯμϜ஋Ͱςετ͞ΕΔ
    • 4XJGU$IFDLͰ9$5FTUͱ૊Έ߹Θͤͯ࢖͑Δ
    • ࢖͍Ͳ͜Ζ
    • ޻෉࣍ୈͰ͍Ζ͍Ζ͋Γͦ͏
    • &YBNQMFCBTFEUFTUJOHͱ஥ྑ͘
    

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72. &OKPZUIF5FTU
    72
    Copyright (C) DeNA Co.,Ltd. All Rights Reserved.
    

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