Add tests

Package.swift

@@ -4,62 +4,109 @@
 import PackageDescription
 
 let package = Package(
-    name: "SnapshotPreviews",
-    platforms: [.iOS(.v15), .macOS(.v12), .watchOS(.v9)],
-    products: [
-        // Products define the executables and libraries a package produces, making them visible to other packages.
-        .library(
-          name: "PreviewGallery",
-          type: .static, // Replace this to build dynamic
-          targets: ["PreviewGallery"]),
-        // Test library to import in your XCTest target.
-        // This is the only library that depends on XCTest.framework
-        .library(
-          name: "SnapshottingTests",
-          type: .static, // Replace this to build dynamic
-          targets: ["SnapshottingTests"]),
-        // Link the main app to this target to use custom snapshot settings
-        // This lib does not get inserted when running tests to avoid
-        // duplicate symbols.
-        .library(
-          name: "SnapshotPreferences",
-          targets: ["SnapshotPreferences"]),
-        // Core functionality for snapshotting exported from the internal package
-        .library(
-          name: "SnapshotPreviewsCore",
-          targets: ["SnapshotPreviewsCore"]),
-        // Dynamic library that your main app will have inserted to generate previews
-        .library(
-          name: "Snapshotting",
-          type: .dynamic,
-          targets: ["Snapshotting"]),
-    ],
-    dependencies: [
-      .package(url: "https://github.com/swhitty/FlyingFox.git", exact: "0.16.0"),
-      .package(url: "https://github.com/EmergeTools/AccessibilitySnapshot.git", exact: "1.0.2"),
-      .package(url: "https://github.com/EmergeTools/SimpleDebugger.git", exact: "1.0.0"),
-    ],
-    targets: [
-        // Targets are the basic building blocks of a package, defining a module or a test suite.
-        // Targets can depend on other targets in this package and products from dependencies.
-        // Target that provides the XCTest
-      .target(name: "SnapshottingTestsObjc", dependencies: [.product(name: "SimpleDebugger", package: "SimpleDebugger", condition: .when(platforms: [.iOS, .macOS, .macCatalyst]))]),
-        .target(name: "SnapshottingTests", dependencies: ["SnapshotPreviewsCore", "SnapshottingTestsObjc"]),
-        .target(name: "SnapshotSharedModels"),
-        // Core functionality
-        .target(name: "SnapshotPreviewsCore", dependencies: ["PreviewsSupport", "SnapshotSharedModels", .product(name: "AccessibilitySnapshotCore", package: "AccessibilitySnapshot", condition: .when(platforms: [.iOS, .macCatalyst]))]),
-        .target(name: "SnapshotPreferences", dependencies: ["SnapshotSharedModels"]),
-        // Inserted dylib
-        .target(name: "Snapshotting", dependencies: ["SnapshottingSwift"]),
-        // Swift code in the inserted dylib
-        .target(name: "SnapshottingSwift", dependencies: ["SnapshotPreviewsCore", .product(name: "FlyingFox", package: "FlyingFox")]),
-        .target(name: "PreviewGallery", dependencies: ["SnapshotPreviewsCore", "SnapshotPreferences"]),
-        .binaryTarget(
-          name: "PreviewsSupport",
-          path: "PreviewsSupport/PreviewsSupport.xcframework"),
-        .testTarget(
-            name: "SnapshotPreviewsTests",
-            dependencies: ["SnapshotPreviewsCore"]),
-    ],
-    cxxLanguageStandard: .cxx11
+  name: "SnapshotPreviews",
+  platforms: [.iOS(.v15), .macOS(.v12), .watchOS(.v9)],
+  products: [
+    // Products define the executables and libraries a package produces, making them visible to other packages.
+    .library(
+      name: "PreviewGallery",
+      type: .static,  // Replace this to build dynamic
+      targets: ["PreviewGallery"]
+    ),
+    // Test library to import in your XCTest target.
+    // This is the only library that depends on XCTest.framework
+    .library(
+      name: "SnapshottingTests",
+      type: .static,  // Replace this to build dynamic
+      targets: ["SnapshottingTests"]
+    ),
+    // Link the main app to this target to use custom snapshot settings
+    // This lib does not get inserted when running tests to avoid
+    // duplicate symbols.
+    .library(
+      name: "SnapshotPreferences",
+      targets: ["SnapshotPreferences"]
+    ),
+    // Core functionality for snapshotting exported from the internal package
+    .library(
+      name: "SnapshotPreviewsCore",
+      targets: ["SnapshotPreviewsCore"]
+    ),
+    // Dynamic library that your main app will have inserted to generate previews
+    .library(
+      name: "Snapshotting",
+      type: .dynamic,
+      targets: ["Snapshotting"]
+    ),
+  ],
+  dependencies: [
+    .package(url: "https://github.com/swhitty/FlyingFox.git", exact: "0.16.0"),
+    .package(
+      url: "https://github.com/EmergeTools/AccessibilitySnapshot.git",
+      exact: "1.0.2"
+    ),
+    .package(
+      url: "https://github.com/EmergeTools/SimpleDebugger.git",
+      exact: "1.0.0"
+    ),
+  ],
+  targets: [
+    // Targets are the basic building blocks of a package, defining a module or a test suite.
+    // Targets can depend on other targets in this package and products from dependencies.
+    // Target that provides the XCTest
+    .target(
+      name: "SnapshottingTestsObjc",
+      dependencies: [
+        .product(
+          name: "SimpleDebugger",
+          package: "SimpleDebugger",
+          condition: .when(platforms: [.iOS, .macOS, .macCatalyst])
+        )
+      ]
+    ),
+    .target(
+      name: "SnapshottingTests",
+      dependencies: ["SnapshotPreviewsCore", "SnapshottingTestsObjc"]
+    ),
+    .target(name: "SnapshotSharedModels"),
+    // Core functionality
+    .target(
+      name: "SnapshotPreviewsCore",
+      dependencies: [
+        "PreviewsSupport", "SnapshotSharedModels",
+        .product(
+          name: "AccessibilitySnapshotCore",
+          package: "AccessibilitySnapshot",
+          condition: .when(platforms: [.iOS, .macCatalyst])
+        ),
+      ]
+    ),
+    .target(
+      name: "SnapshotPreferences",
+      dependencies: ["SnapshotSharedModels"]
+    ),
+    // Inserted dylib
+    .target(name: "Snapshotting", dependencies: ["SnapshottingSwift"]),
+    // Swift code in the inserted dylib
+    .target(
+      name: "SnapshottingSwift",
+      dependencies: [
+        "SnapshotPreviewsCore",
+        .product(name: "FlyingFox", package: "FlyingFox"),
+      ]
+    ),
+    .target(
+      name: "PreviewGallery",
+      dependencies: ["SnapshotPreviewsCore", "SnapshotPreferences"]
+    ),
+    .binaryTarget(
+      name: "PreviewsSupport",
+      path: "PreviewsSupport/PreviewsSupport.xcframework"
+    ),
+    .testTarget(
+      name: "SnapshotPreviewsTests",
+      dependencies: ["SnapshotPreviewsCore", "SnapshotPreferences"]
+    ),
+  ],
+  cxxLanguageStandard: .cxx11
 )

Sources/SnapshotPreviewsCore/ConformanceLookup.swift

@@ -8,107 +8,109 @@
 import Foundation
 import MachO
 
-private func getTypeName(descriptor: UnsafePointer<TargetModuleContextDescriptor>) -> String? {
-  let flags = descriptor.pointee.flags
-  var parentName: String? = nil
-  if descriptor.pointee.parent != 0 {
-    let parent = UnsafeRawPointer(descriptor).advanced(by: MemoryLayout<TargetModuleContextDescriptor>.offset(of: \.parent)!).advanced(by: Int(descriptor.pointee.parent))
-    if abs(descriptor.pointee.parent) % 2 == 1 {
-      return nil
-    }
-    parentName = getTypeName(descriptor: parent.assumingMemoryBound(to: TargetModuleContextDescriptor.self))
-  }
-  switch flags.kind {
-  case .Module, .Enum, .Struct, .Class:
-    let name = UnsafeRawPointer(descriptor)
-      .advanced(by: MemoryLayout<TargetModuleContextDescriptor>.offset(of: \.name)!)
-      .advanced(by: Int(descriptor.pointee.name))
-      .assumingMemoryBound(to: CChar.self)
-    let typeName = String(cString: name)
-    if let parentName = parentName {
-      return "\(parentName).\(typeName)"
-    }
-    return typeName
-  default:
-    return parentName
-  }
-}
-
 public typealias LookupResult = (name: String, accessor: () -> UInt64, proto: String)
 
-private func parseConformance(conformance: UnsafePointer<ProtocolConformanceDescriptor>) -> LookupResult? {
-  let flags = conformance.pointee.conformanceFlags
-
-  guard case .DirectTypeDescriptor = flags.kind else {
-    return nil
-  }
-
-  guard conformance.pointee.protocolDescriptor % 2 == 1 else {
-    return nil
-  }
-  let descriptorOffset = Int(conformance.pointee.protocolDescriptor & ~1)
-  let jumpPtr = UnsafeRawPointer(conformance).advanced(by: MemoryLayout<ProtocolConformanceDescriptor>.offset(of: \.protocolDescriptor)!).advanced(by: descriptorOffset)
-  let address = jumpPtr.load(as: UInt64.self)
-
-  // Address will be 0 if the protocol is not available (such as only defined on a newer OS)
-  guard address != 0 else {
-    return nil
+public class ConformanceLookup {
+  public static func getPreviewTypes() -> [LookupResult] {
+    let images = _dyld_image_count()
+    var types = [LookupResult]()
+    for i in 0..<images {
+      let imageName = String(cString: _dyld_get_image_name(i))
+      // System frameworks on the simulator are in Xcode.app/Contents/** (Although Xcode could be renamed like Xcode-beta.app so don't check for that specifically)
+      guard !imageName.contains(".simruntime") && !imageName.contains(".app/Contents/Developer") && !imageName.starts(with: "/usr/lib/") else {
+        continue
+      }
+
+      let header = _dyld_get_image_header(i)!
+      var size: UInt = 0
+      let sectStart = UnsafeRawPointer(
+        getsectiondata(
+          UnsafeRawPointer(header).assumingMemoryBound(to: mach_header_type.self),
+          "__TEXT",
+          "__swift5_proto",
+          &size))?.assumingMemoryBound(to: Int32.self)
+      if var sectData = sectStart {
+        for _ in 0..<Int(size)/MemoryLayout<Int32>.size {
+          let conformance = UnsafeRawPointer(sectData)
+            .advanced(by: Int(sectData.pointee))
+            .assumingMemoryBound(to: ProtocolConformanceDescriptor.self)
+          if let result = parseConformance(conformance: conformance) {
+            types.append(result)
+          }
+          sectData = sectData.successor()
+        }
+      }
+    }
+    return types
   }
-  let protoPtr = UnsafeRawPointer(bitPattern: UInt(address))!
-  let proto = protoPtr.load(as: ProtocolDescriptor.self)
-  let namePtr = protoPtr.advanced(by: MemoryLayout<ProtocolDescriptor>.offset(of: \.name)!).advanced(by: Int(proto.name))
-  let protocolName = String(cString: namePtr.assumingMemoryBound(to: CChar.self))
-  guard ["PreviewProvider", "PreviewRegistry"].contains(protocolName) else {
+
+  private static func parseConformance(conformance: UnsafePointer<ProtocolConformanceDescriptor>) -> LookupResult? {
+    let flags = conformance.pointee.conformanceFlags
+
+    guard case .DirectTypeDescriptor = flags.kind else {
+      return nil
+    }
+
+    guard conformance.pointee.protocolDescriptor % 2 == 1 else {
+      return nil
+    }
+    let descriptorOffset = Int(conformance.pointee.protocolDescriptor & ~1)
+    let jumpPtr = UnsafeRawPointer(conformance).advanced(by: MemoryLayout<ProtocolConformanceDescriptor>.offset(of: \.protocolDescriptor)!).advanced(by: descriptorOffset)
+    let address = jumpPtr.load(as: UInt64.self)
+
+    // Address will be 0 if the protocol is not available (such as only defined on a newer OS)
+    guard address != 0 else {
+      return nil
+    }
+    let protoPtr = UnsafeRawPointer(bitPattern: UInt(address))!
+    let proto = protoPtr.load(as: ProtocolDescriptor.self)
+    let namePtr = protoPtr.advanced(by: MemoryLayout<ProtocolDescriptor>.offset(of: \.name)!).advanced(by: Int(proto.name))
+    let protocolName = String(cString: namePtr.assumingMemoryBound(to: CChar.self))
+    guard ["PreviewProvider", "PreviewRegistry"].contains(protocolName) else {
+      return nil
+    }
+
+    let typeDescriptorPointer = UnsafeRawPointer(conformance).advanced(by: MemoryLayout<ProtocolConformanceDescriptor>.offset(of: \.nominalTypeDescriptor)!).advanced(by: Int(conformance.pointee.nominalTypeDescriptor))
+
+    let descriptor = typeDescriptorPointer.assumingMemoryBound(to: TargetModuleContextDescriptor.self)
+    if let name = getTypeName(descriptor: descriptor),
+       [ContextDescriptorKind.Class, ContextDescriptorKind.Struct, ContextDescriptorKind.Enum].contains(descriptor.pointee.flags.kind) {
+      let accessFunctionPointer = UnsafeRawPointer(descriptor).advanced(by: MemoryLayout<TargetModuleContextDescriptor>.offset(of: \.accessFunction)!).advanced(by: Int(descriptor.pointee.accessFunction))
+      let accessFunction = unsafeBitCast(accessFunctionPointer, to: (@convention(c) () -> UInt64).self)
+      return (name, accessFunction, protocolName)
+    }
     return nil
   }
-
-  let typeDescriptorPointer = UnsafeRawPointer(conformance).advanced(by: MemoryLayout<ProtocolConformanceDescriptor>.offset(of: \.nominalTypeDescriptor)!).advanced(by: Int(conformance.pointee.nominalTypeDescriptor))
-
-  let descriptor = typeDescriptorPointer.assumingMemoryBound(to: TargetModuleContextDescriptor.self)
-  if let name = getTypeName(descriptor: descriptor),
-     [ContextDescriptorKind.Class, ContextDescriptorKind.Struct, ContextDescriptorKind.Enum].contains(descriptor.pointee.flags.kind) {
-    let accessFunctionPointer = UnsafeRawPointer(descriptor).advanced(by: MemoryLayout<TargetModuleContextDescriptor>.offset(of: \.accessFunction)!).advanced(by: Int(descriptor.pointee.accessFunction))
-    let accessFunction = unsafeBitCast(accessFunctionPointer, to: (@convention(c) () -> UInt64).self)
-    return (name, accessFunction, protocolName)
+
+  private static func getTypeName(descriptor: UnsafePointer<TargetModuleContextDescriptor>) -> String? {
+    let flags = descriptor.pointee.flags
+    var parentName: String? = nil
+    if descriptor.pointee.parent != 0 {
+      let parent = UnsafeRawPointer(descriptor).advanced(by: MemoryLayout<TargetModuleContextDescriptor>.offset(of: \.parent)!).advanced(by: Int(descriptor.pointee.parent))
+      if abs(descriptor.pointee.parent) % 2 == 1 {
+        return nil
+      }
+      parentName = getTypeName(descriptor: parent.assumingMemoryBound(to: TargetModuleContextDescriptor.self))
+    }
+    switch flags.kind {
+    case .Module, .Enum, .Struct, .Class:
+      let name = UnsafeRawPointer(descriptor)
+        .advanced(by: MemoryLayout<TargetModuleContextDescriptor>.offset(of: \.name)!)
+        .advanced(by: Int(descriptor.pointee.name))
+        .assumingMemoryBound(to: CChar.self)
+      let typeName = String(cString: name)
+      if let parentName = parentName {
+        return "\(parentName).\(typeName)"
+      }
+      return typeName
+    default:
+      return parentName
+    }
   }
-  return nil
 }
 
 #if arch(i386) || arch(arm) || arch(arm64_32)
 typealias mach_header_type = mach_header
 #else
 typealias mach_header_type = mach_header_64
 #endif
-
-public func getPreviewTypes() -> [LookupResult] {
-  let images = _dyld_image_count()
-  var types = [LookupResult]()
-  for i in 0..<images {
-    let imageName = String(cString: _dyld_get_image_name(i))
-    // System frameworks on the simulator are in Xcode.app/Contents/** (Although Xcode could be renamed like Xcode-beta.app so don't check for that specifically)
-    guard !imageName.contains(".simruntime") && !imageName.contains(".app/Contents/Developer") && !imageName.starts(with: "/usr/lib/") else {
-      continue
-    }
-
-    let header = _dyld_get_image_header(i)!
-    var size: UInt = 0
-    let sectStart = UnsafeRawPointer(
-      getsectiondata(
-        UnsafeRawPointer(header).assumingMemoryBound(to: mach_header_type.self),
-        "__TEXT",
-        "__swift5_proto",
-        &size))?.assumingMemoryBound(to: Int32.self)
-    if var sectData = sectStart {
-      for _ in 0..<Int(size)/MemoryLayout<Int32>.size {
-        let conformance = UnsafeRawPointer(sectData)
-          .advanced(by: Int(sectData.pointee))
-          .assumingMemoryBound(to: ProtocolConformanceDescriptor.self)
-        if let result = parseConformance(conformance: conformance) {
-          types.append(result)
-        }
-        sectData = sectData.successor()
-      }
-    }
-  }
-  return types
-}