SwiftSyntaxMacrosに入門してみた

Transcript

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2. ϚΫϩʹೖ໳ͨ͠Ϟνϕʔγϣϯ
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   protocol APIClient {
   
   
   func fetchUserName(userId: Int) async throws -> String
   
   
   func setUserFlag(userId: Int, flag: Bool) async throws
   
   
   }
   struct APIClient {
   
   
   var fetchUserName: @Sendable (_ userId: Int) async throws -> String
   
   
   var setUserFlag: @Sendable (_ userId: Int, _ flag: Bool) async throws -> Void
   
   
   }
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3. ࠓճ࡞੒͢Δ!(FOFSBUF.PDLϚΫϩ
   @GenerateMock
   
   
   struct APIClient {
   
   
   var fetch: @Sendable (Int) async throws -> String
   
   
   }
   struct APIClient {
   
   
   var fetch: @Sendable (Int) async throws -> String
   
   
   static func mock(_ mock: Mock) -> Self {
   
   
   Self (fetch: mock.fetch)
   
   
   }
   
   
   class Mock {
   
   
   private(set) var fetchCallCount = 0
   
   
   private(set) var fetchArgValues: [(Int)] = []
   
   
   var fetchHandler: ((Int) async throws -> String)?
   
   
   @Sendable fileprivate func fetch(_ arg0: Int) async throws -> String {
   
   
   fetchCallCount += 1
   
   
   fetchArgValues.append((arg0))
   
   
   return try await fetchHandler!(arg0)
   
   
   }
   
   
   }
   
   
   }
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   Λอ࣋͢ΔΫϥε.PDL
   

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4. public struct GenerateMockMacro: MemberMacro {
   
   
   public static func expansion(
   
   
   of node: AttributeSyntax,
   
   
   providingMembersOf declaration: some DeclGroupSyntax,
   
   
   in context: some MacroExpansionContext
   
   
   ) throws -> [DeclSyntax] {
   
   
   return [DeclSyntax("")]
   
   
   }
   
   
   }
   w .FNCFS.BDSPͷFYQBOTJPOϝιου಺ʹɺϚΫϩͷ࣮૷Λॻ͍͍ͯ͘
   ϚΫϩΛ৽ن࡞੒͢Δ
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   ͜͜Ͱฦͨ͠4ZOUBY͕ɺϚΫϩͰల։͞ΕΔ
   @attached(member, names: named(mock(_:)), named(Mock))
   
   
   public macro GenerateMock() = #externalMacro(module: "GenerateMockMacros", type: "GenerateMockMacro")
   w ࠓճ͸TUSVDUʹϝϯόʔΛ௥Ճ͍ͨ͠ͷͰ!BUUBDIFE NFNCFS
   Λઃఆ
   

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5. ςετΛ༻ҙ͢Δ
   w ςετΛ܁Γฦ࣮͠ߦ͠ͳ͕Βɺগͣͭ͠ϚΫϩΛ૊Έཱ͍ͯͯ͘
   final class GenerateMockTests: XCTestCase {
   
   
   func testMacro() throws {
   
   
   assertMacroExpansion(#"""
   
   
   @GenerateMock
   
   
   struct APIClient {
   
   
   var fetch: @Sendable (Int) async throws -> String
   
   
   }
   
   
   """#,
   
   
   expandedSource: #"""
   
   
   struct APIClient {
   
   
   var fetch: @Sendable (Int) async throws -> String
   
   
   }
   
   
   """#,
   
   
   macros: ["GenerateMock": GenerateMockMacro.self]
   
   
   )
   
   
   }
   
   
   }
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   ςετ͕௨Δ
   

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6. ςετΛॻ͖׵͑Δ
   w ςετʹTUBUJDؔ਺Λ௥Ճͯ͠ɺظ଴௨Γͷࠩ෼Ͱࣦഊ͢Δ͜ͱΛ֬ೝ
   assertMacroExpansion(#"""
   
   
   @GenerateMock
   
   
   struct APIClient {
   
   
   var fetch: @Sendable (Int) async throws -> String
   
   
   }
   
   
   """#,
   
   
   expandedSource: #"""
   
   
   struct APIClient {
   
   
   var fetch: @Sendable (Int) async throws -> String
   
   
   static func mock(_ mock: Mock) -> Self {
   
   
   Self (fetch: mock.fetch)
   
   
   }
   
   
   }
   
   
   """#,
   
   
   macros: testMacros
   
   
   )
   

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8. 'VODUJPO%FDM4ZOUBYΛߏங͢Δ
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   return [
   
   
   DeclSyntax(
   
   
   FunctionDeclSyntax(
   
   
   name: <#T##TokenSyntax#>,
   
   
   signature: <#T##FunctionSignatureSyntax#>
   
   
   )
   
   
   )
   
   
   ]
   name: TokenSyntax(stringLiteral: “mock"),
   
   
   signature: FunctionSignatureSyntax(
   
   
   parameterClause: <#T##FunctionParameterClauseSyntax#>
   
   
   )
   w OBNFͱTJHOBUVSFͱ͍͏ύϥϝʔλΛٻΊΒΕͨͷͰɺຒΊͯΈΔ
   w TJHOBUVSF͸ɺ͞ΒʹQBSBNFUFS$MBVTFͱ͍͏΋ͷΛٻΊ͖ͯͨ
   

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9. QBSBNFUFS$MBVTFΛຒΊΔ
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   parameterClause: FunctionParameterClauseSyntax(
   
   
   parameters: FunctionParameterListSyntax([
   
   
   FunctionParameterSyntax(stringLiteral: "_ mock: Mock")
   
   
   ])
   
   
   )
   ࣍͸ઌ಄ʹTUBUJDΛ෇͚ͯΈΑ͏
   

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10. TUBUJDΛ෇͚Δ
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    fi
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    FunctionDeclSyntax(
    
    
    modifiers: DeclModifierListSyntax([
    
    
    DeclModifierSyntax(name: "static")
    
    
    ]),
    
    
    name: TokenSyntax(stringLiteral: "mock"),
    
    
    signature: FunctionSignatureSyntax(…)
    
    
    )
    

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11. 4FMGΛฦ͢
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    ͋ͱ͸ؔ਺ʹίʔυϒϩοΫΛ௥Ճ͢Δ͚ͩʂ
    signature: FunctionSignatureSyntax(
    
    
    parameterClause: FunctionParameterClauseSyntax(…),
    
    
    returnClause: ReturnClauseSyntax(
    
    
    type: IdentifierTypeSyntax(name: "Self")
    
    
    )
    
    
    )
    

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12. ͜Μͳײ͡ͷϊϦͰ૊Έཱ͍ͯͯ͘ΜͰ͕͢ʜ
    struct APIClient {
    
    
    var fetch: @Sendable (Int) async throws -> String
    
    
    static func mock(_ mock: Mock) -> Self {
    
    
    Self (fetch: mock.fetch)
    
    
    }
    
    
    }
    w ϚΫϩͷೖྗΛղੳ͢Δඞཁ͕͋Δ
    w ͜ΕΒͷ໊લʢGFUDIʣ͸ ͔͜͜Βऔ͖͍ͬͯͨ
    

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13. ϚΫϩೖྗΛղੳ͢Δ
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    StructDeclSyntax
    
    
    ├─attributes: AttributeListSyntax
    
    
    │ ╰─[0]: AttributeSyntax
    
    
    │ ├─atSign: atSign
    
    
    │ ╰─attributeName: IdentifierTypeSyntax
    
    
    │ ╰─name: identifier("GenerateMock")
    
    
    ├─modifiers: DeclModifierListSyntax
    
    
    ├─structKeyword: keyword(SwiftSyntax.Keyword.struct)
    
    
    ├─name: identifier("APIClient")
    
    
    ╰─memberBlock: MemberBlockSyntax
    
    
    ├─leftBrace: leftBrace
    
    
    ├─members: MemberBlockItemListSyntax
    
    
    │ ╰─[0]: MemberBlockItemSyntax
    
    
    │ ╰─decl: VariableDeclSyntax
    
    
    │ ├─attributes: AttributeListSyntax
    
    
    │ ├─modifiers: DeclModifierListSyntax
    
    
    │ ├─bindingSpecifier: keyword(SwiftSyntax.Keyword.var)
    
    
    │ ╰─bindings: PatternBindingListSyntax
    
    
    │ ╰─[0]: PatternBindingSyntax
    
    
    │ ├─pattern: IdentifierPatternSyntax
    
    
    │ │ ╰─identifier: identifier("fetch")
    
    
    │ ╰─typeAnnotation: TypeAnnotationSyntax
    
    
    │ ├─colon: colon
    
    
    │ ╰─type: AttributedTypeSyntax
    
    
    │ ├─attributes: AttributeListSyntax
    
    
    │ │ ╰─[0]: AttributeSyntax
    
    
    │ │ ├─atSign: atSign
    
    
    │ │ ╰─attributeName: IdentifierTypeSyntax
    
    
    │ │ ╰─name: identifier("Sendable")
    
    
    │ ╰─baseType: FunctionTypeSyntax
    
    
    │ ├─leftParen: leftParen
    
    
    │ ├─parameters: TupleTypeElementListSyntax
    
    
    │ │ ╰─[0]: TupleTypeElementSyntax
    
    
    │ │ ╰─type: IdentifierTypeSyntax
    
    
    │ │ ╰─name: identifier("Int")
    
    
    │ ├─rightParen: rightParen
    
    
    │ ├─effectSpecifiers: TypeEffectSpecifiersSyntax
    
    
    │ │ ├─asyncSpecifier: keyword(SwiftSyntax.Keyword.async)
    
    
    │ │ ╰─throwsSpecifier: keyword(SwiftSyntax.Keyword.throws)
    
    
    │ ╰─returnClause: ReturnClauseSyntax
    
    
    │ ├─arrow: arrow
    
    
    │ ╰─type: IdentifierTypeSyntax
    
    
    │ ╰─name: identifier("String")
    
    
    ╰─rightBrace: rightBrace
    public static func expansion(
    
    
    of node: AttributeSyntax,
    
    
    providingMembersOf declaration: some DeclGroupSyntax,
    
    
    in context: some MacroExpansionContext
    
    
    ) throws -> [DeclSyntax] {
    
    
    print(declaration.debugDescription)
    
    
    return [DeclSyntax(…)]
    
    
    }
    w ϚΫϩʹೖྗ͞Εͨίʔυͷߏจ໦͕
    

    ΞεΩʔΞʔτܗࣜͰग़ྗ͞ΕΔ
    

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14. Ϋϩʔδϟͷม਺໊Λऔಘ͢Δ
    StructDeclSyntax
    
    
    ╰─memberBlock: MemberBlockSyntax
    
    
    ├─members: MemberBlockItemListSyntax
    
    
    │ ╰─[0]: MemberBlockItemSyntax
    
    
    │ ╰─decl: VariableDeclSyntax
    
    
    │ ╰─bindings: PatternBindingListSyntax
    
    
    │ ╰─[0]: PatternBindingSyntax
    
    
    │ ├─pattern: IdentifierPatternSyntax
    
    
    │ │ ╰─identifier: identifier("fetch")
    guard let structDecl = declaration.as(StructDeclSyntax.self),
    
    
    let variable = structDecl.memberBlock.members.first?.decl.as(VariableDeclSyntax.self),
    
    
    let identifierPattern = variable.bindings.first?.pattern.as(IdentifierPatternSyntax.self)
    
    
    else { throw CustomError.message("...") }
    
    
    print(identifierPattern.identifier) // => "fetch"
    w దٓΩϟετΛར༻͠ͳ͕Βɺ໨౰ͯͷཁૉ·ͰͨͲ͍ͬͯ͘
    

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15. ϚΫϩ͕׬੒
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    w ͱΓ͋͑ͣಈ͖ͦ͏ͳϚΫϩ͕׬੒͠·ͨ͠ʙʂ🎉
    w IUUQTHJUIVCDPNUPDIJ(FOFSBUF.PDL
    

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16. ࣮ࡍʹ࢖ͬͯΈͨ
    w "1*$MJFOUͱTXJGUEFQFOEFODJFTͰར༻͢ΔͨΊͷ͓·͡ͳ͍Λهड़
    @GenerateMock
    
    
    struct APIClient {
    
    
    var fetchUserName: @Sendable (_ userId: Int) async throws -> String
    
    
    var setUserFlag: @Sendable (_ userId: Int, _ flag: Bool) async throws -> Void
    
    
    }
    
    
    extension APIClient: DependencyKey {
    
    
    static let liveValue = Self(
    
    
    fetchUserName: { "Live user for \($0)" },
    
    
    setUserFlag: { _, _ in try await Task.sleep(nanoseconds: NSEC_PER_SEC) }
    
    
    )
    
    
    }
    
    
    extension DependencyValues {
    
    
    var apiClient: APIClient {
    
    
    get { self[APIClient.self] }
    
    
    set { self[APIClient.self] = newValue }
    
    
    }
    
    
    }
    

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17. ࣮ࡍʹ࢖ͬͯΈͨ
    w "1*$MJFOUΛར༻͢Δ7JFX.PEFMΛهड़
    @MainActor
    
    
    final class ViewModel: ObservableObject {
    
    
    @Published private(set) var text: String?
    
    
    @Published private(set) var isLoading = false
    
    
    @Dependency(\.apiClient) private var apiClient
    
    
    private let userId: Int
    
    
    init(userId: Int) { self.userId = userId }
    
    
    func buttonTapped() async {
    
    
    text = nil
    
    
    isLoading = true; defer { isLoading = false }
    
    
    do {
    
    
    text = try await apiClient.fetchUserName(userId)
    
    
    try await apiClient.setUserFlag(userId, true)
    
    
    } catch {
    
    
    text = "Error!"
    
    
    }
    
    
    }
    
    
    }
    
    
    

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18. ࣮ࡍʹ࢖ͬͯΈͨ
    w ςετͷTFU6QͰɺϚΫϩʹΑΓੜ੒͞Εͨ"1*$MJFOUͷϞοΫʹࠩ͠ସ͑
    @MainActor
    
    
    final class ViewModelTests: XCTestCase {
    
    
    var sut: ViewModel!
    
    
    var apiClientMock: APIClient.Mock!
    
    
    override func setUp() {
    
    
    super.setUp()
    
    
    apiClientMock = .init()
    
    
    sut = withDependencies {
    
    
    $0.apiClient = .mock(apiClientMock)
    
    
    } operation: {
    
    
    ViewModel(userId: 1234)
    
    
    }
    
    
    }
    
    
    ...
    
    
    }
    
    
    

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19. ࣮ࡍʹ࢖ͬͯΈͨ
    w ςετ͸͜Μͳײ͡Ͱ
    

    ॻ͚Δ
    func testButtonTapped_Success() async {
    
    
    apiClientMock.fetchUserNameHandler = { "Mock user for \($0)" }
    
    
    apiClientMock.setUserFlagHandler = { _, _ in }
    
    
    await sut.buttonTapped()
    
    
    XCTAssertEqual(sut.text, "Mock user for 1234")
    
    
    XCTAssertEqual(apiClientMock.fetchUserNameCallCount, 1)
    
    
    XCTAssertEqual(apiClientMock.fetchUserNameArgValues, [1234])
    
    
    XCTAssertEqual(apiClientMock.setUserFlagCallCount, 1)
    
    
    XCTAssertEqual(apiClientMock.setUserFlagArgValues.map(\.userId), [1234])
    
    
    XCTAssertEqual(apiClientMock.setUserFlagArgValues.map(\.flag), [true])
    
    
    }
    
    
    func testButtonTapped_Failure() async {
    
    
    apiClientMock.fetchUserNameHandler = { _ in
    
    
    struct SomeError: Error {}
    
    
    throw SomeError()
    
    
    }
    
    
    await sut.buttonTapped()
    
    
    XCTAssertEqual(sut.text, "Error!")
    
    
    XCTAssertEqual(apiClientMock.fetchUserNameCallCount, 1)
    
    
    XCTAssertEqual(apiClientMock.fetchUserNameArgValues, [1234])
    
    
    XCTAssertEqual(apiClientMock.setUserFlagCallCount, 0)
    
    
    }
    w GFUDIʹ੒ޭͨ͠৔߹͸
    

    ϑϥάઃఆ͕ݺ͹ΕΔ
    w GFUDIʹࣦഊͨ͠৔߹͸
    

    ϑϥάઃఆ͕ݺ͹Εͳ͍
    

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20. ࣮ࡍʹ࢖ͬͯΈͨ
    w Ұ౓໨͸ࣦഊͯ͠ɺϦτϥΠͨ͠Β
    

    ੒ޭ͢ΔΑ͏ͳςετ΋ॻ͚Δ
    func testButtonTapped_RetryWithLoading() async {
    
    
    await withMainSerialExecutor {
    
    
    apiClientMock.fetchUserNameHandler = { _ in
    
    
    await Task.yield()
    
    
    struct SomeError: Error {}
    
    
    throw SomeError()
    
    
    }
    
    
    let task1 = Task { await sut.buttonTapped() }
    
    
    await Task.yield()
    
    
    XCTAssertTrue(sut.isLoading)
    
    
    XCTAssertNil(sut.text)
    
    
    await task1.value
    
    
    XCTAssertFalse(sut.isLoading)
    
    
    XCTAssertEqual(sut.text, "Error!")
    
    
    apiClientMock.fetchUserNameHandler = {
    
    
    await Task.yield()
    
    
    return "Mock user for \($0)"
    
    
    }
    
    
    apiClientMock.setUserFlagHandler = { _, _ in }
    
    
    let task2 = Task { await sut.buttonTapped() }
    
    
    await Task.yield()
    
    
    XCTAssertTrue(sut.isLoading)
    
    
    XCTAssertNil(sut.text)
    
    
    await task2.value
    
    
    XCTAssertFalse(sut.isLoading)
    
    
    XCTAssertEqual(sut.text, "Mock user for 1234")
    
    
    }
    
    
    }
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    w 5BTLZJFME
    Λ࢖༻͢Δςετ͸ɺ
    

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    w ৄ͘͠͸1PJOU'SFFͷ
    

    υΩϡϝϯτΛ͝ཡ͍ͩ͘͞
    

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21. ·ͱΊ
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    շదͳ4XJGUϓϩάϥϛϯάੜ׆ΛૹΓ·͠ΐ͏ʙ👍👍
    

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