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

Slide 1

Slide 1 text

Slide 2

Slide 2 text

˙: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. 2

Slide 3

Slide 3 text

Slide 4

Slide 4 text

Slide 5

Slide 5 text

Slide 6

Slide 6 text

Slide 7

Slide 7 text

Slide 8

Slide 8 text

Slide 9

Slide 9 text

Slide 10

Slide 10 text

Slide 11

Slide 11 text

Slide 12

Slide 12 text

Slide 13

Slide 13 text

// 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 Copyright (C) DeNA Co.,Ltd. All Rights Reserved. 1 + 2 ͷ݁Ռ͸ 3 Ͱ͋Δ͜ͱ • ҰൠతͳY6OJU͕ఏڙ͍ͯ͠Δํ๏ • 2VJDLͳͲͷ#%%ͳ'8΋ຊ࣭తʹ͸ಉ͡

Slide 14

Slide 14 text

Slide 15

Slide 15 text

Slide 16

Slide 16 text

Slide 17

Slide 17 text

Slide 18

Slide 18 text

Slide 19

Slide 19 text

Slide 20

Slide 20 text

Slide 21

Slide 21 text

Slide 22

Slide 22 text

Slide 23

Slide 23 text

Slide 24

Slide 24 text

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) } }

Slide 25

Slide 25 text

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

Slide 26

Slide 26 text

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஋

Slide 27

Slide 27 text

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

Slide 28

Slide 28 text

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

Slide 29

Slide 29 text

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

Slide 30

Slide 30 text

Slide 31

Slide 31 text

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

Slide 32

Slide 32 text

Slide 33

Slide 33 text

۩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

Slide 34

Slide 34 text

Slide 35

Slide 35 text

*** 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

Slide 36

Slide 36 text

Slide 37

Slide 37 text

Slide 38

Slide 38 text

Slide 39

Slide 39 text

Slide 40

Slide 40 text

Slide 41

Slide 41 text

Slide 42

Slide 42 text

Slide 43

Slide 43 text

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

Slide 44

Slide 44 text

Slide 45

Slide 45 text

͜͜·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

Slide 46

Slide 46 text

Slide 47

Slide 47 text

Slide 48

Slide 48 text

Slide 49

Slide 49 text

Arbitrary 49 Copyright (C) DeNA Co.,Ltd. All Rights Reserved. • 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] }

Slide 50

Slide 50 text

Slide 51

Slide 51 text

Shrinking 51 Copyright (C) DeNA Co.,Ltd. All Rights Reserved. • ʮऩॖ͢Δʯͱ͍ͬͨҙຯ • ಉ͘͡"SCJUSBSZϓϩτίϧʹఆٛʢPQUJPOBMʣ • ΑΓখ͞ͳ஋ʹ͢Δ໾ׂ • ͜ΕʹΑΓࣦഊͨ͠ςετσʔλʹ͍ͭͯɺ  ΑΓখ͞ͳࣦഊέʔεΛબग़͢Δ࢓૊Έ Int.shrink(10) // => [0, 1, 2, 5] String.shrink(“app") // => ["p", "pp", ... ,"apa", "apb"]

Slide 52

Slide 52 text

Slide 53

Slide 53 text

Slide 54

Slide 54 text

Slide 55

Slide 55 text

Slide 56

Slide 56 text

Slide 57

Slide 57 text

Slide 58

Slide 58 text

Slide 59

Slide 59 text

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 }

Slide 60

Slide 60 text

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

Slide 61

Slide 61 text

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

Slide 62

Slide 62 text

༷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+_

Slide 63

Slide 63 text

Slide 64

Slide 64 text

Slide 65

Slide 65 text

Slide 66

Slide 66 text

֊৐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

Slide 67

Slide 67 text

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

Slide 68

Slide 68 text

Slide 69

Slide 69 text

Slide 70

Slide 70 text

Slide 71

Slide 71 text

·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஥ྑ͘

Slide 72

Slide 72 text