dotnet-testing-datetime-testing-timeprovider

name

dotnet-testing-datetime-testing-timeprovider

description

使用 TimeProvider 測試時間相依邏輯的專門技能。當需要測試 DateTime、控制時間流逝、處理時區轉換、測試過期邏輯時使用。涵蓋 TimeProvider 抽象化、FakeTimeProvider 時間控制、時間凍結與快轉等。 Make sure to use this skill whenever the user mentions DateTime testing, TimeProvider, FakeTimeProvider, time-dependent logic, cache expiration, or token expiration testing, even if they don't explicitly ask for time testing guidance. Keywords: datetime, time testing, 時間測試, TimeProvider, FakeTimeProvider, DateTime.Now, 時間相依, 快取過期, token 過期, Microsoft.Bcl.TimeProvider, GetUtcNow, SetUtcNow, Advance, time freeze, 時間凍結, 時間快轉

DateTime 與時間相依性測試指南

核心原則

原則一：時間抽象化 - 以 TimeProvider 取代 DateTime

傳統問題程式碼：

// ❌ 無法測試 - 直接使用靜態時間
public class OrderService
{
    public bool CanPlaceOrder()
    {
        var now = DateTime.Now;
        return now.Hour >= 9 && now.Hour < 17;
    }
}

可測試的重構：

// ✅ 可測試 - 透過依賴注入接收 TimeProvider
public class OrderService
{
    private readonly TimeProvider _timeProvider;
    
    public OrderService(TimeProvider timeProvider)
    {
        _timeProvider = timeProvider ??   ArgumentNullException((timeProvider));
    }
    
    
    {
         now = _timeProvider.GetLocalNow();
         now.Hour >=  && now.Hour < ;
    }
}