「SOLID原則(一部)」と Testability の関係 iOS 編

ʮ40-*%ݪଇ Ұ෦ ʯͱ 5FTUBCJMJUZͷؔ܎ J04ฤ 4IJO0IOP JEHBODIJLV

"CPVUNZTFMG w 4IJO0IOP JEHBODIJLV w ΏΊΈJ04ςοΫϦʔυʢճୀ৔ɺճೖ৔ʣ w ΋ͱ͸αʔόʔαΠυΤϯδχΞ w
͔ͭͯ͸ɺΧϯϑΝϨϯεͷӳޠݍήετͷ௨༁ʗ຋༁໾

U@XBEB͞Μߨशձ͕͋Γ·ͨ͠

ΞδΣϯμ w ࠓ೔ͷ࿩ͷλʔήοτ w 40-*%ݪଇͱ4561*% w %* 4- OFX w
%*ݏ͍ͷצҧ͍ w 4XJGUͰͷ%*ͷओͳύλʔϯ w %*Ͱςελϒϧͳ։ൃ΁

ࠓ೔ͷ࿩ͷλʔήοτ w ओʹϞσϧ෦ w ϨΠϠʔυΞʔΩςΫνϟͰݴ͏4FSWJDF૚ w ΞϓϦέʔγϣϯϨΠϠʔͷ6TF$BTF૚ w 6*෦ʹؔͯ͠͸ޮՌతͳςετʹؔͯ͠ɺ·ͩΑ͘Θ ͔͍ͬͯͳ͍ʢ࣮ࡍ͸ඍົͳσβΠϯௐ੔౳͕ΞϓϦ։ൃ
ͷҰ൪ͭΒ͍ͱ͜Ζʣ ίίʂ

ςετΛॻ͚ͱݴ͏͚ΕͲ w ςετ͕ॻ͖΍͍͢ίʔυͱॻ͖ʹ͍͘ίʔυ͕͋Δ w ςετ͕ॻ͖΍͍͢ w ੹຿͕໌֬ɺந৅ʹґଘ͍ͯ͠Δ w ςετ͕ॻ͖ʹ͍͘ w
ͭͷΫϥεɺͭͷϝιουͰ΍Γ͗͢ɺ۩৅ʹґଘ ͍ͯ͠ΔɺTUBUJD͕ଟ͍ɺඇಉظॲཧ

40-*%ݪଇ w 44JOHMFSFTQPOTJCJMJUZQSJODJQMF 431 w 00QFODMPTFEQSJODJQMF 0$1 w
--JTDPWTVCTUJUVUJPOQSJODJQMF -41 w **OUFSGBDFTFHSFHBUJPOQSJODJQMF *41 w %%FQFOEFODZJOWFSTJPOQSJODJQMF %*1 https://cleancoders.com/videos?series=clean-code&subseries=solid-principles

શ෦ങͬͯɺͱ͖Ͳ͖ݟ͍ͯ·͢

ݪଇΛकΕ͍ͯͳ͍ͱ w 431͕कΒΕ͍ͯͳ͍ͱ w ҰͭͷΫϥεɺҰͭͷϝιουͰ͍ΖΜͳ৚݅ͷςετΛॻ͘ඞཁ͕͋ Δɻमਖ਼͢ΔࡍͷӨڹൣғ͕େ͖͍ɻ w 0$1͕कΒΕ͍ͯͳ͍ͱ w मਖ਼͢Δ౓ʹΤϯόάͷՄೳੑ͕͋Δ͠ɺӨڹ͕େ͖͍ɻΠϯλʔ
ϑΣʔεઃܭ͕ϛε͍ͬͯΔɻϞοΫςετ͕ॻ͖ʹ͍͘ɻ w %*1͕कΒΕ͍ͯͳ͍ͱ w ۩ମతͳ࣮૷ʹґଘͯ͠͠·͏ͷͰɺऔΓସ͑ʹ͍͘ɻ·ͨɺ0$1ͷ ҧ൓Λ༠ൃ͢Δɻ

ີ݁߹ͳίʔυ͸ Өڹൣғͷௐ͕ࠪࠔ೉Ͱ मਖ਼͠ʹ͘͘ ςετ͕ॻ͖ʹ͍͘

4561*% w 44JOHMFUPOʢγϯάϧτϯ5ʹͭͳ͕Δʣ w 55JHIU$PVQMJOHʢ͕͜͜ବ໨ͩͱςετॻ͚ͳ͍ʣ w 66OUFTUBCJMJUZʢ5ͷ݁ՌͰ͋Δ͜ͱ͕ଟ͍ʣ w 11SFNBUVSF0QUJNJ[BUJPOʢ࣌ظঘૣͳ࠷దԽʣ w
**OEFTDSJQUJWF/BNJOHʢΠέͯͳ͍ωʔϛϯάʣ w %%VQMJDBUJPOʢॏෳʣ https://williamdurand.fr/2013/07/30/from-stupid-to-solid-code/ http://nikic.github.io/2011/12/27/Dont-be-STUPID-GRASP-SOLID.html

-PPTF$PVQMJOH0WFS%3: w ౓໨ͷ๏ଇʢϦϑΝΫλϦϯάʣ w ࠷ॳ͸୯७ʹ࡞ۀ͢Δ w ̎౓໨ʹʮҎલͱࣅͨΑ͏ͳ͜ͱΛ͍ͯ͠Δʯͱؾ͍ͮͨࡍ ͸ॏෳΛҙࣝͭͭ͠࡞ۀΛ͢Δ w ౓໨ʹಉ͡Α͏ͳ͜ͱΛ͍ͯͨ͠ΒϦϑΝΫλϦϯάର৅
ͱ͢Δ w %3:ΑΓ΋ૄ݁߹͕ॏཁͳཱͪҐஔͷɺཁ͸όϥϯε͓͡͞Μ

40-*%ݪଇͱ4561*% ·ͱΊ w 40-*%ݪଇେࣄ ݪଇΛ஌্ͬͨͰ࠾༻͠ͳ͍͜ͱ΋͋Δ w զʑͷ࡞͍ͬͯΔιϑτ΢ΣΞ͸Ұ౓࡞ͬͯऴΘΓͰ͸ͳ ͍ɻৼΔ෣͍ͷ࣮૷͕มΘͬͯ΋ྑ͍Α͏ʹ͢Δ΂͖ɻ w
ૄ݁߹ͳํ͕मਖ਼ʹରͯ͠ɺӨڹൣғΛ཈͑Δ͜ͱ͕Ͱ͖ Δɻີ݁߹͸͔ͳΓະདྷΛಡΉઃܭྗ͕ٻΊΒΕɺ೉͠ ͍ʢυϝΠϯ஌͕ࣝ๛෋Ͱมߋ͠ͳ͍ݻ͞ͷ͋Δ΋ͷͳΒ ͍͚Δ͔΋͘Β͍ʣɻ

%* 4- w ີ݁߹Λආ͚ͯɺૄ݁߹ʹ͢Δύλʔϯ w 4FSWJDF-PDBUPS 4- w ίϯςφɺϩέʔλʔ͔ΒґଘΛड͚औΔ
w %FQFOEFODZ*OKFDUJPO %* w ΠϯλʔϑΣʔεɺϓϩτίϧ͔ΒґଘΛड͚औΔ

Կ͔ॲཧΛ͢ΔαʔϏε Λґଘͤ͞Δ protocol SomethingServiceProtocol: class { func doSomething() } class
SomethingService: SomethingServiceProtocol { func doSomething() { print("It's never too late to learn.") } } /// γϯάϧτϯͰ static ʹݺͼग़͢৔߹ class SomethingStaticService: SomethingService { static let shared = SomethingStaticService() private override init() { } }

/FXͰੜ੒ ʢີ݁߹ʣ class NewDependency { let service: SomethingServiceProtocol init() {
service = SomethingService() } func completeWork() { service.doSomething() } } let newDependency = NewDependency() newDependency.completeWork()

TUBUJDͰੜ੒ ʢີ݁߹ʣ class StaticDependency { let service: SomethingServiceProtocol init() {
service = SomethingStaticService.shared } func completeWork() { service.doSomething() } } let staticDependency = StaticDependency() staticDependency.completeWork()

4-ʢૄ݁߹ʣ -PDBUPSʹ༧Ίొ࿥ class ServiceLocator { static let shared = ServiceLocator()
private var container = [String:Any]() private init() { } func register() { container["somethingService"] = SomethingService() } func getSomethingService() -> SomethingServiceProtocol { return container["somethingService"] as! SomethingServiceProtocol } }

4-ʢૄ݁߹ʣ #VU-PDBUPSʹґଘ class SLDependency { let locator: ServiceLocator init(locator: ServiceLocator)
{ self.locator = locator } func completeWork() { locator.getSomethingService().doSomething() } } ServiceLocator.shared.register() let slDependency = SLDependency(locator: ServiceLocator.shared) slDependency.completeWork()

%*ʢૄ݁߹ʣ ϓϩτίϧʹґଘ class DIDependency { let service: SomethingServiceProtocol init(service: SomethingServiceProtocol)
{ self.service = service } func completeWork() { service.doSomething() } } let diDependency = DIDependency(service: SomethingService()) diDependency.completeWork() ίϯετϥΫλΠϯδΣΫγϣϯ

%* 4- OFX ·ͱΊ w OFXʹΑΓੜ੒͞ΕͨґଘɺTUBUJDʹΑΓੜ੒͞Εͨґ ଘ͕͋Δͱີ݁߹ʹͳͬͯ͠·͏ɻ w 4-ʹΑΓੜ੒͞Εͨґଘ͸ɺૄ݁߹Ͱ͋Δ͕ɺMPDBUPS ͕(PEɻԿ͕ొ࿥͞Ε͍ͯΔ͔஌Δඞཁ͕͋Δɻ
w %*ʹΑΓੜ੒͞Εͨґଘ͸ɺૄ݁߹Ͱ͋Γɺந৅͋Γɺ मਖ਼ͳͯ͘͠ɺ֦ு͢Δ͜ͱ͕Ͱ͖Δɻ

ͱ͜ΖͰɺ%*%*$ %*Λ࣮ݱ͢ΔͨΊͷ࢓૊ΈͷҰͭͰ͋ͬͯɺ %*$͸ॏཁͰ͸ͳ͍ w %*$ͷ࢖͍ํ͕Θ͔Βͳ͍ w ΞϊςʔγϣϯͳͲͰͷఆ͕ٛΘ͔Βͳ͍ %*ͳΜͯݏ͍

7JFX$POUSPMMFSੜ੒࣌ʹґଘ Ϛοϓ஌Βͳ͍ͱ͍͚ͳ͍ʁ 7JFX $POUSPMMFS 7JFX .PEFM 4PNF 4FSWJDF" 4PNF 4FSWJDF#
4PNF 4FSWJDF$

7JFX$POUSPMMFS΁ͷґଘղ ܾ͸ٞ࿦͋Γ w 7JFX$POUSPMMFS͕ґଘ͢ΔϚοϓΛ࣋ͭ w %*$ͳͲ ॳظԽॲཧʹ࢓ࠐΉ Λ࢖ͬͯࣗಈతʹηοτ͞ Ε͍ͯΔঢ়ଶΛ࡞ͬͯ͠·͏ w
%*$ʢ4FSWJDF-PDBUPSʣͷΠϯελϯε͔Β͖࣋ͬͯ ͯɺґଘղܾ͸ͦ͜Ͱߦ͏ɻ ແཧήʔͩ͠ੜ੒͞Ε ͨ΋ͷڞ༗Ͱ͖ͳ͍ʁ Ͳ͜Ͱఆ͍ٛͯ͠Δ͔ Θ͔Γʹ͍͔͘΋ʁ ͋ͷάϩʔόϧͳ γϯάϧτϯΰουʁ

ࣗ෼ͷཱͪҐஔ ཁ͸όϥϯε͓͡͞Μ w 7JFX$POUSPMMFSͳͲॳظԽ͕ίϯτϩʔϧ͠ʹ͍͘΋ͷ ʹ͓͍ͯ͸ɺ%*$ 4FSWJDF-PDBUPS ͔Βґଘ͢ΔαʔϏ εʢ6TF$BTF 7JFX.PEFM౳ʣΛऔಘ͢Δɻ w
ϩδοΫͷू߹ମͰ͋Δ6TF$BTF૚ɺ4FSWJDF૚ʹ͓͍ͯ ͸ɺ4FSWJDF-PDBUPSͷίϯςφͰ͸ͳ͘ɺ%*ͷϓϩτ ίϧͰґଘ͢ΔαʔϏεΛऔಘ͢Δɻ

%*ݏ͍ͷצҧ͍ ·ͱΊ w %*%*$ʢ%*͸େࣄɺ%*$͸ศར͕ͩɺͳΜͰ΋͍͍ʣ w 7JFX$POUSPMMFS͸গ͠໽հ͔ͩΒ%*$Λ4-తʹ࢖ͬͯ ΋ྑ͍ελϯε w ϩδοΫΛ࣋ͭ6TF$BTF 4FSWJDF͸ϓϩτίϧʹґଘ
ͤ͞Α͏

͚͓ͭͩئ͍͕͋Γ·͢ɻ %*$ͷ͜ͱ͸ݏ͍Ͱ΋ɺ %*ͷ͜ͱ͸ݏ͍ʹͳΒͳ͍Ͱ͍ͩ͘͞ɻ

%*ͷओͳύλʔϯ w $POTUSVDUPS4FUUFS*OKFDUJPO w ॳظԽ΍ηολʔͰґଘ͢ΔΦϒδΣΫτΛड͚औΔ w %*$Λ࢖͏ͱ͖͸͜ΕΒΛ࢖͏͜ͱ͕ଟ͍ w $BLF1BUUFSO w
1SPUPDPM&YUFOTJPOΛ࢖ͬͯɺґଘ͢ΔΦϒδΣΫτΛ౉͢ w 4DBMBք۾ͰΑ͘࢖ΘΕΔʁ

$POTUSVDUPS4FUUFS *OKFDUJPO class DIDependency { let service: SomethingServiceProtocol init(service: SomethingServiceProtocol)
{ self.service = service } func completeWork() { service.doSomething() } } let diDependency = DIDependency(service: SomethingService()) diDependency.completeWork()

$BLF1BUUFSO protocol CakePatternProtocol { var service: SomethingServiceProtocol { get }
func completeWork() } extension CakePatternProtocol { func completeWork() { service.doSomething() } } class Main { } extension Main: CakePatternProtocol { var service: SomethingServiceProtocol { return SomethingService() } } WBSͰఆٛ͢Δͷ͸ͪΐͬͱݏ

4XJGUͰͷ%* ·ͱΊ w $POTUSVDUPS4FUUFS*OKFDUJPO w 001 0CKFDU0SJFOUF1SPHSBNNJOH ͳΠϝʔδ w $BLF1BUUFSO
w 101 1SPUPDPM0SJFOUFE1SPHSBNNJOH ͳΠϝʔδ

ίϯετϥΫλΠϯδΣΫγϣϯ ͷςετ protocol SomethingServiceProtocol: class { func doSomething() -> String
} class SomethingService: SomethingServiceProtocol { func doSomething() -> String { return "It's never too late to learn." } } let service: SomethingServiceProtocol init(service: SomethingServiceProtocol) { self.service = service } func completeWork() -> String { return "---\(service.doSomething())---" } } ̿SJOU͸͋·Γςετ͸ ҙຯ͕ͳ͍ͷͰɺ 4USJOHΛฦ͢ͷͱ গ͠Ճ޻͢ΔΑ͏ʹ मਖ਼͍ͯ͠·͢

ίϯετϥΫλΠϯδΣΫγϣϯ ͷςετ func testCompleteWorkFailed() { class FailedService: SomethingServiceProtocol { func
doSomething() -> String { return "FAILED" } } let sut = DIConstructorInjectionDependency(service: FailedService()) XCTAssertNotEqual("FAILED", sut.completeWork()) } func testCompleteWorkSucceeded() { class SuccessService: SomethingServiceProtocol { func doSomething() -> String { return "SUCCEEDED" } } let sut = DIConstructorInjectionDependency(service: SuccessService()) XCTAssertEqual("---SUCCEEDED---", sut.completeWork()) }

$BLF1BUUFSOͷςετ protocol SomethingServiceProtocol: class { func doSomething() -> String }
protocol CakePatternProtocol { var service: SomethingServiceProtocol { get } func completeWork() -> String } extension CakePatternProtocol { func completeWork() -> String { return "---\(service.doSomething())---" } }

$BLF1BUUFSOͷςετ func testCompleteWorkFailed() { class FailedService: SomethingServiceProtocol { func doSomething()
-> String { return "FAILED" } } class CakePattern: CakePatternProtocol { var service: SomethingServiceProtocol = FailedService() } let sut = CakePattern() XCTAssertNotEqual("FAILED", sut.completeWork()) } func testCompleteWorkSucceeded() { class SuccessService: SomethingServiceProtocol { func doSomething() -> String { return "SUCCEEDED" } } class CakePattern: CakePatternProtocol { var service: SomethingServiceProtocol = SuccessService() } let sut = CakePattern() XCTAssertEqual("---SUCCEEDED---", sut.completeWork()) }

ࣗ෼ͷॻ͍ͨίʔυͷ͜ͱ͸୨ʹ্͛ͯ·͢ɻ N @@ N

「SOLID原則(一部)」と Testability の関係 iOS 編

「SOLID原則(一部)」と Testability の関係 iOS 編

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