chore: import upstream snapshot with attribution

tests/fixtures/sample.swift

@@ -0,0 +1,83 @@
+import Foundation
+import UIKit
+
+protocol Processor {
+    func process() -> [String]
+}
+
+protocol Loggable {
+    func log()
+}
+
+class BaseProcessor {}
+
+class Result<T> {}
+
+class DataProcessor: BaseProcessor, Processor {
+    private var items: [String] = []
+    var current: Result<DataProcessor> = Result<DataProcessor>()
+
+    init() {}
+
+    deinit {}
+
+    func addItem(_ item: String) {
+        items.append(item)
+    }
+
+    func process() -> [String] {
+        return validate(items)
+    }
+
+    func run(input: DataProcessor) -> Result<DataProcessor> {
+        return current
+    }
+
+    private func validate(_ data: [String]) -> [String] {
+        return data.filter { !$0.isEmpty }
+    }
+}
+
+struct Config {
+    let baseUrl: String
+    let timeout: Int
+
+    subscript(key: String) -> String? {
+        return nil
+    }
+}
+
+enum NetworkError {
+    case timeout
+    case connectionFailed
+    case unauthorized
+    case failed(Config)
+
+    func describe() -> String {
+        return "error"
+    }
+}
+
+actor CacheManager {
+    private var store: [String: String] = [:]
+
+    func get(_ key: String) -> String? {
+        return store[key]
+    }
+}
+
+extension DataProcessor: Loggable {
+    func log() {
+        print("logging")
+    }
+}
+
+extension Config {
+    func isValid() -> Bool {
+        return !baseUrl.isEmpty
+    }
+}
+
+func createProcessor() -> DataProcessor {
+    return DataProcessor()
+}