qa-cache-testing
Cache testing across layers: Redis cache patterns, CDN cache-purge testing (Cloudflare, Fastly, CloudFront), Varnish VTC syntax, browser Cache-Control tests, cache-coherence + stampede + stale-while-revalidate references, and a cache-key collision detector. Covers RFC 9111 HTTP caching and the canonical multi-tier cache discipline (browser to CDN to app to data store).
Install this plugin
/plugin install qa-cache-testing@testland-qaPart of role bundle: qa-role-backend
qa-cache-testing
Cache testing across layers: Redis cache patterns, CDN cache-purge testing (Cloudflare, Fastly, CloudFront), Varnish VTC syntax, browser Cache-Control tests, cache-coherence + stampede + stale-while-revalidate references, and a cache-key collision detector. Covers RFC 9111 HTTP caching and the canonical multi-tier cache discipline (browser to CDN to app to data store).
Components
| Type | Name | Description |
|---|---|---|
| Skill | browser-cache-control-tests | Wraps browser-side Cache-Control testing patterns using Playwright (and Cypress for legacy stacks): verifying response Cache-Control head... |
| Skill | cache-coherence-patterns-reference | Pure-reference catalog of cache-coherence patterns across the request path. |
| Skill | cache-stampede-reference | Pure-reference catalog of cache-stampede (thundering-herd) phenomena and mitigations. |
| Skill | cdn-cache-purge-tests | Wraps CDN cache-purge testing patterns for Cloudflare (POST /zones/{zone_id}/purge_cache, single-file / everything / cache-tags / hostnam... |
| Skill | memcached-tests | Wraps Memcached cache testing patterns: text and binary protocol command verification (set/get/add/cas/incr/decr), TTL semantics (0=never... |
| Skill | redis-cache-tests | Wraps Redis cache testing patterns: EXPIRE / PEXPIRE / TTL command verification (with the Redis 7+ NX/XX/GT/LT flags), the cache-aside wr... |
| Skill | stale-while-revalidate-reference | Pure-reference catalog of RFC 5861's stale-while-revalidate + stale-if-error Cache-Control extensions. |
| Skill | varnish-test-vtc-syntax | Wraps the varnishtest CLI + VTC (Varnish Test Case) syntax for testing VCL configurations. |
| Skill | cache-key-discriminator-audit | Audits whether a cache key carries every discriminator the response depends on, ranking identity discriminators above presentation ones because a missing tenant is a data leak, not a performance bug. |
| Agent | cache-key-collision-detector | Read-only specialist that scans application code for cache-key collision risks - keys that should be unique per (tenant, user, locale, re... |
Install
/plugin marketplace add testland/qa
/plugin install qa-cache-testing@testland-qaSkills
browser-cache-control-tests
Wraps browser-side Cache-Control testing with Playwright (Cypress for legacy stacks): asserting response Cache-Control headers from Network events, ETag round-trips (If-None-Match → 304), service-worker strategies (Workbox cacheFirst / networkFirst / staleWhileRevalidate), and reload semantics (normal vs hard). Covers MDN Cache-Control + RFC 9111. Use when auditing browser-tier caching in E2E tests. For CDN-edge purge use cdn-cache-purge-tests; for the reverse-proxy tier use varnish-test-vtc-syntax; for an app-tier store use redis-cache-tests; SWR directive semantics live in stale-while-revalidate-reference.
cache-coherence-patterns-reference
Pure-reference catalog of cache-coherence patterns across the request path. Defines the five-tier cache stack (browser → CDN → reverse-proxy → application → data store), the per-tier cache-writing patterns (cache-aside, write-through, write-back, write-around, refresh-ahead), and the canonical invalidation strategies (TTL-only, event-driven purge, surrogate keys, version-tagged URLs, soft purge), plus an anti-pattern table and a worked multi-tenant coherence-test example. Deep detail - the RFC 9111 Cache-Control / Vary / ETag directive tables and the cross-tier coherence + per-tier test surface - lives in references/. Use for pattern selection, Cache-Control header design, and coherence audits; use a cache-key-collision check when the question is whether two requests in an existing system collide on a concrete key scheme. Consumed by redis-cache-tests, cdn-cache-purge-tests, varnish-test-vtc-syntax, browser-cache-control-tests, and the cache-key-collision check.
cache-key-discriminator-audit
Audits whether a cache key carries every discriminator the cached response actually depends on, so two requests that must not share a slot cannot collide. Ranks identity discriminators (tenant, user, authorization scope, plan tier) above presentation ones (locale, region, currency, feature flag), maps each missing discriminator to the data-exposure or wrong-content consequence it causes, classifies each key-and-value pair into a critical / high / medium severity band (including the Python lru_cache-on-an-instance-method trap), and writes the fix as a namespaced key builder plus the matching HTTP Vary header. Use when a cache key is being designed or changed, when a per-user or per-tenant response is about to be stored in a shared cache or CDN, or when investigating a report that one user or tenant saw another's data.
cache-stampede-reference
Pure-reference catalog of cache-stampede (thundering-herd) phenomena and mitigations: parallel misses on key expiry trigger simultaneous recomputation (often congestion-collapse), countered by three families - locking, external recomputation near-expiry, and probabilistic early expiration via XFetch (`(time() - delta * beta * log(rand(0,1))) >= expiry`). Use when designing cache-refresh strategy or diagnosing a stampede incident. This is the single failure-mode pattern; for the broader multi-tier pattern catalog use cache-coherence-patterns-reference, for the stale-while-revalidate / stale-if-error extensions use stale-while-revalidate-reference; a reference consumed by redis-cache-tests, not a runnable test.
cdn-cache-purge-tests
Wraps CDN cache-purge testing patterns for Cloudflare (POST /zones/{zone_id}/purge_cache, single-file / everything / cache-tags / hostname / prefix), Fastly (POST purge-by-key / purge-all, surrogate-keys via Surrogate-Key header), and CloudFront (CreateInvalidation API + paths). Covers end-to-end test patterns (write origin → trigger purge → assert edge serves fresh), purge-propagation delay testing (typically 1-30s globally), surrogate-key + cache-tag patterns for group-purge, and Cache-Status header verification (cf-cache-status: HIT/MISS/BYPASS). Use when designing or auditing CDN cache-invalidation workflows.
memcached-tests
Wraps Memcached cache testing against a real container: an inline set/get/expire/no-persistence worked example, with the exhaustive protocol-command tests (set/get/add/cas/incr/decr, TTL 0=never-expire / 30-day Unix-timestamp boundary) and the LRU-eviction, consistent-hashing distribution, ElastiCache Auto Discovery, and CI-wiring deep-dives in references/. Use when writing tests for an application that uses Memcached as its primary cache, when verifying ElastiCache Memcached cluster behaviour, or when contrasting Memcached eviction and distribution semantics against Redis.
redis-cache-tests
Wraps Redis cache testing: EXPIRE / PEXPIRE / TTL verification (Redis 7+ NX/XX/GT/LT flags), cache-aside write-then-invalidate (write source → DEL key → assert fresh read), eviction under memory pressure (maxmemory + allkeys-lru), pub/sub invalidation across nodes, and tenant key-namespacing. Use when Redis is the app's primary cache. For a Memcached app-tier store use memcached-tests; for the browser/HTTP tier use browser-cache-control-tests; a runnable test, not the cache-stampede-reference or cache-coherence-patterns-reference catalogs.
stale-while-revalidate-reference
Pure-reference catalog of RFC 5861's stale-while-revalidate + stale-if-error Cache-Control extensions. Defines stale-while-revalidate=N (caches MAY serve a stale response while asynchronously revalidating, up to N seconds after expiry) and stale-if-error=N (caches MAY serve stale on 5xx upstream errors). Distinguishes from RFC 9111's must-revalidate (forbids serving stale) and from manual cache-aside refresh (synchronous). Covers the interaction with the freshness lifetime (max-age) and the cache-stampede-mitigation properties. Use when designing the cache-refresh boundary or auditing existing Cache-Control headers.
varnish-test-vtc-syntax
Wraps the varnishtest CLI + VTC (Varnish Test Case) syntax for testing VCL configurations. Covers the VTC test-file format (varnishtest scripts with server { ... } + client { ... } + varnish v1 -vcl+backend { ... } blocks), the grace-mode + saint-mode behaviours (stale-while-revalidate + stale-if-error equivalents in VCL), the PURGE method handler pattern (vcl_purge subroutine + ACL guards), and surrogate-key invalidation via xkey vmod. Use when authoring or testing Varnish-based caching layers.