Duende.Extensions.Caching.Memory

A TimeProvider-based implementation of IMemoryCache that enables testable time-dependent caching. This exists because of this outstanding issue. This library will be obsolete once that issue is resolved in some future version of .NET SDK.

Overview

This library provides a wrapper around Microsoft.Extensions.Caching.Memory.MemoryCache that integrates with .NET's TimeProvider abstraction. This allows you to:

• Write unit tests that manipulate time using FakeTimeProvider
• Verify cache expiration behavior without real delays
• Maintain full compatibility with the standard IMemoryCache interface

Usage

Direct Instantiation

var timeProvider = TimeProvider.System; // or FakeTimeProvider in tests
var options = Options.Create(new TimeProviderMemoryCacheOptions
{
    ExpirationScanFrequency = TimeSpan.FromMinutes(1),
    SizeLimit = 1024
});

var cache = new TimeProviderMemoryCache(timeProvider, options);

// Use like any IMemoryCache
cache.Set("key", "value", TimeSpan.FromMinutes(5));

Dependency Injection

// Basic registration (uses TimeProvider.System)
services.AddTimeProviderMemoryCache();

// With configuration
services.AddTimeProviderMemoryCache(options =>
{
    options.ExpirationScanFrequency = TimeSpan.FromMinutes(1);
    options.SizeLimit = 1024;
});

Testing Example

var fakeTime = new FakeTimeProvider();
var cache = new TimeProviderMemoryCache(fakeTime, options);

cache.Set("key", "value", TimeSpan.FromMinutes(5));

// Advance time past expiration
fakeTime.Advance(TimeSpan.FromMinutes(6));

// Entry should be expired
cache.TryGetValue("key", out var result).ShouldBeFalse();

License

Apache 2.0 - see LICENSE for details.