memory-cache

Memory Cache

A bounded, TTL-expiring, in-memory key-value cache. Entries live for a configured time-to-live and the cache evicts its least-recently-used key when capacity is reached. Great for practicing injected clocks, explicit sweeps, and generic domain types with test data builders.

What this kata teaches

• Test Data Builders — CacheBuilder().WithCapacity(n).WithTtl(...).WithClock(clock).Build() returns a (Cache, Clock) tuple so tests advance time.
• Injected Clock — Clock is a collaborator interface; FixedClock in tests lets TTL expiry tests drive the behavior deterministically.
• Explicit Sweep — evictExpired() mirrors library-management's ExpireReservations and video-club-rental's MarkOverdueRentals. Expiry is a consequence of time passing, not of a user action; the sweep is the production caller's responsibility.
• Domain Exception Types — CacheCapacityInvalidException and CacheTtlInvalidException name the rejection, rather than throwing a generic Error/ValueError.
• Generic Value Type — Cache<V> (C#/TS) / Cache[V] (Python) keeps the cache polymorphic without leaking concrete types into the domain.

See SCENARIOS.md for the shared specification.