Decoding nested structs

import Foundation

struct Test1: Codable {
    var testDate: Date? = nil
    let name: String
    let age: Int
    
    enum CodingKeys: String, CodingKey {
        case name
        case age
    }
}

let json = """
{
"name": "test",
"age": 30,
}
"""


let jsonData = Data(json.utf8)
var test1 = try? JSONDecoder().decode(Test1.self, from: jsonData)
test1?.testDate = Date()

var currentTest: Test1? {
    get {
        let defaults = UserDefaults.standard
        guard let testData = defaults.object(forKey: "test1") as? Data,
            let test = try? PropertyListDecoder().decode(Test1.self,
                                                         from: testData) else {
                                                            return nil
        }
        
        return test
    }
    set {
        let defaults = UserDefaults.standard
        defaults.set(try? PropertyListEncoder().encode(newValue), forKey: "test1")
    }
}

currentTest = test1

print(test1)
print(currentTest)
print(currentTest?.testDate)