如何在Swift中对私有或内部函数进行单元测试？

// MyApp.swift
class MyClass {
    private func privateFunction() -> Int {
        return 42
    }
    
    internal func internalFunction() -> String {
        return "Hello, World!"
    }
}

// MyAppTests.swift
@testable import MyApp
import XCTest

class MyClassTests: XCTestCase {
    func testPrivateFunction() {
        let myClass = MyClass()
        
        let mirror = Mirror(reflecting: myClass)
        if let privateFunction = mirror.descendant("privateFunction") as? () -> Int {
            let result = privateFunction()
            XCTAssertEqual(result, 42, "Private function should return 42")
        } else {
            XCTFail("Private function not found")
        }
    }
    
    func testInternalFunction() {
        let myClass = MyClass()
        
        let result = myClass.internalFunction()
        XCTAssertEqual(result, "Hello, World!", "Internal function should return 'Hello, World!'")
    }
}