Sync migrated iOS modules

suixinkanTests/TestFixture.swift

@@ -0,0 +1,35 @@
+//
+//  TestFixture.swift
+//  suixinkanTests
+//
+//  Created by Codex on 2026/6/22.
+//
+
+import Foundation
+@testable import suixinkan
+
+/// 测试 Fixture 读取工具，用于复用旧工程迁移过来的 JSON 响应。
+enum TestFixture {
+    /// 读取指定名称的 JSON fixture。
+    static func data(named name: String, filePath: String = #filePath) throws -> Data {
+        let url = URL(fileURLWithPath: filePath)
+            .deletingLastPathComponent()
+            .appendingPathComponent("Fixtures")
+            .appendingPathComponent("\(name).json")
+        return try Data(contentsOf: url)
+    }
+
+    /// 读取并解包后端统一 Envelope。
+    static func payload<T: Decodable>(_ type: T.Type, named name: String) throws -> T {
+        let envelope = try JSONDecoder().decode(APIEnvelope<T>.self, from: data(named: name))
+        guard let payload = envelope.data else {
+            throw FixtureError.emptyPayload
+        }
+        return payload
+    }
+}
+
+/// 测试 Fixture 错误实体。
+enum FixtureError: Error {
+    case emptyPayload
+}