In Memory Cache Laravel Package

Getting Started

Install the package via Composer (composer require beste/in-memory-cache) and start using it immediately—no configuration required. It implements Psr\Cache\CacheItemPoolInterface, so it works out of the box with any PSR-6–aware code. The simplest use case is unit testing: replace Redis, Doctrine Cache, or other persistent drivers with InMemoryCache to ensure fast, isolated, deterministic tests. For TTL-sensitive logic, inject a beste/clock\FrozenClock to control time explicitly. Begin by instantiating new InMemoryCache() or new InMemoryCache($clock) in your tests or dev environment.

Implementation Patterns

• Test-specific instantiation: Create a fresh InMemoryCache instance per test (e.g., via setUp() in PHPUnit or before() in Pest) to guarantee state isolation—critical when asserting hit/miss behavior or expiration.
• Time-controlled testing: Combine with beste/clock\FrozenClock (or a custom PSR-20 clock) to simulate cache expiration without real delays. Set time to just before expiry, assert hit; advance time past TTL, assert miss. This is essential for validating fallback logic, middleware caching, or rate-limiting.
• Environment-based driver swap: Wrap InMemoryCache in a custom CacheInterface (e.g., App\Contracts\Cache) and swap implementations via Laravel’s config (e.g., use InMemoryCache in testing and Redis in production). Laravel’s CacheManager respects PSR-6, so you can even register it as a custom driver via Cache::extend().
• Mocking cache behavior in integration tests: In API or service-level tests, inject InMemoryCache instead of external services to avoid flaky network calls or DB fixtures. Ideal for verifying cache-first patterns (e.g., “fetch from cache or compute + store”).

Gotchas and Tips

• No cross-request persistence: The cache lives only in the current PHP process—data is lost between HTTP requests or CLI invocations. Never use it for production state; reserve for tests, CLI scripts, or dev-time fallbacks.
• Key flexibility has limits: While v1.2.0+ allows dashes and removes the 64-char limit, PSR-6 still expects at least alphanumeric + _.. If interoperability matters (e.g., dropping in Doctrine Cache later), avoid exotic keys like user:123, foo-bar`, or emojis.
• Default clock is implicit but functional: Since v1.1.0, new InMemoryCache() uses PHP’s built-in SystemClock. Fine for dev—but always inject a frozen clock in tests. Missing this causes non-deterministic failures when TTLs are close to real time.
• Memory leakage risk in long-running tests: In large test suites (especially pest with --parallel or Behat), in-memory items accumulate. Call $cache->clear() in after() or manually delete items post-test to avoid OOM in CLI runs.
• It’s final—compose, don’t extend: The class is final, so you can’t subclass. Use decorators (e.g., LoggingCache wrapping InMemoryCache) or Laravel’s Cache::extend() to add metrics, logging, or validation. This keeps your tests clean while preserving encapsulation.