Testing
Unit tests, integration tests, test automation
behavior-driven-testing
by agent-next
Systematic testing methodology for exhaustive branch coverage, edge case identification, and production bug prevention. Use when PR review reveals incomplete test coverage, when tests pass but users report bugs, when code changes break existing features, when verifying all branches and edge cases before merge, when analyzing "it works on my machine" issues, when planning test strategy for new features, or when debugging flaky tests and race conditions.
elite-tester
by truongnat
World-class testing standards focused on the Testing Pyramid, TDD, E2E excellence, and robust test data management. Use when writing unit tests, integration tests, or complex E2E automation for any platform.
go-test-standards
by iceleaf916
Golang 单元测试规范与最佳实践指南
testing-patterns
by vivekgana
pytest fixtures and integration testing patterns for Spark applications, including DataFrame assertions and mock data generation.
playwright-browser
by arlenagreer
Browser automation and E2E testing via local Playwright Docker container
ab-test-setup
by ncdevshiv
"Structured guide for setting up A/B tests with mandatory gates for hypothesis, metrics, and execution readiness."
instrumenting-first-party-metrics
by PostHog
"How to instrument PostHog's own Metrics product from PostHog-owned code — record counters, gauges, and histograms that land in posthog.metrics, the same way customers do. Use when adding application metrics in this monorepo (web, Celery, Temporal), when asked to push or ship metrics into posthog metrics, or when unsure whether the SDK in this environment supports posthog.metrics yet. Covers the environment decision (SDK-first per the public docs, OTel fallback when the SDK path is not available), the exact version gates per SDK, what is already wired internally, and how to validate metrics actually arrive."
posthog-desktop
by PostHog
Scopes work to the desktop app at products/desktop — a nested standalone pnpm/turbo/Biome workspace imported from the now-archived PostHog/code repo, with posthog/posthog the only source of truth for PRs, CI and publishing, and not part of the root frontend or Django build. Use when the user says /posthog-desktop, or works on the Electron desktop app, apps/code, apps/web, apps/mobile, packages/core, packages/ui, packages/workspace-server, @posthog/api-client, @posthog/agent, or the agent framework. Pins the working directory to products/desktop, swaps in that tree's toolchain and conventions in place of the monorepo's, and defines the few paths outside the tree that may be touched (Django APIs the app calls, desktop-* CI at the root).
ingestion-pipeline-doctor-nodejs
by PostHog
Ingestion pipeline architecture overview and convention reference. Use when you need a quick orientation to the pipeline framework or want to know which doctor agent to use for a specific concern.
fixing-flaky-tests
by PostHog
Guides an agent through reproducing, root-causing, fixing, and validating flaky tests in the PostHog monorepo. Use when a test fails intermittently in CI but passes on rerun or locally, when hogli ci:insights or the debugging-ci-failures skill classifies a failure as a flaky test, when given a GitHub Actions URL for a flaky job, when asked to check Trunk Flaky Tests for a test, PR, or master, or when asked to deflake, stabilize, or fix a flaky Jest, pytest, or Playwright test. Core discipline: reproduce locally before changing anything, fix the root cause (never mask it with sleeps, retries, or bigger timeouts), and prove the fix with an N-run validation loop sized to the observed failure rate. Stabilizing is not the only valid outcome — the skill also gates whether the test should exist, so deleting a test that catches nothing real, or re-leveling one that flakes because of the level it runs at, are first-class endings.
extending-personhog-test-harness
by PostHog
When and how to add scenarios, chaos events, and invariants to the personhog e2e test harness (rust/personhog-test-harness). Use after fixing a bug or regression in the personhog leader path (leader, router, writer, replica, coordination protocol) so the fix gets a permanent regression scenario; when adding a new failure mode to test (crashes, drains, zombies, lag, failover); or when a new correctness property needs asserting during runs. Trigger terms: personhog gate, chaos scenario, test harness, leader path regression, handoff bug, eviction, writer lag, acked write.
authoring-ci-workflows
by PostHog
Use when adding or editing a GitHub Actions workflow, composite action, or reusable workflow under .github/ — new CI jobs, triggers, matrices, checkout/clone tuning, action pinning, GitHub App token auth, concurrency groups, timeout-minutes, paths filters, caching, or runner choice. Covers PostHog's workflow-authoring conventions and the reasons behind them: the 500-runs/10s dispatch cap, shallow vs full clone, per-SHA push concurrency, dedicated App-token rate-limit buckets, and fork-safe secrets on a public repo. Points to the linters (bin/hogli lint:workflows, actionlint) that enforce the mechanical rules, and to the narrower skills for production deploys, secrets, and Depot runners. Not for debugging red CI (use debugging-ci-failures) or wiring a new secret end to end (use managing-github-actions-secrets).
writing-tests
by PostHog
Gates whether a new test should exist and forces it to be efficient, protecting CI from low-value test bloat. Use before any change to what a pytest, Jest, or Playwright test asserts or sets up, down to one fixture or one assertion added to an existing block. Front-loads the value bar (every test must catch a realistic regression no existing test already catches; extend the nearest existing test before writing a new standalone one; test behavior through the public interface, not implementation details; collapse near-duplicates into parameterized cases) and the efficiency bar (deterministic, isolated, fast; pick the cheapest test level; Django TestCase over TransactionTestCase; no sleeps, no real network; no time bombs from absolute dates left to age against the real clock). Includes a "don't write it" decision tree. For fixing an existing flaky test use /fixing-flaky-tests; after this gate says a Playwright test is warranted, use /playwright-test for mechanics.
setting-feature-flags-in-storybook
by PostHog
'Use when writing a Storybook story for a component gated on a feature flag — boolean flags or multivariate/experiment-arm variants. Covers the featureFlags story parameter and why imperatively setting flags renders the flag-off branch in visual-regression snapshots while passing in jest.'
cudf-analytics
by langchain-ai
Use for GPU-accelerated data analysis on datasets, CSVs, or tabular data using NVIDIA cuDF. Triggers when tasks involve groupby aggregations, statistical summaries, anomaly detection, or large-scale data profiling.
migrate-to-shoehorn
by mattpocock
Migrate test files from as type assertions to @total-typescript/shoehorn. Use when user mentions shoehorn, wants to replace as in tests, or needs partial test data.
tdd
by mattpocock
Test-driven development. Use when the user wants to build features or fix bugs test-first, mentions "red-green-refactor", or wants integration tests.
game-theory
by brycewang-stanford
This skill covers game-theoretic methods in structural econometrics and industrial organization. Use when the user is working with strategic interactions, equilibrium analysis, or game-theoretic structural models — including entry games, conduct testing, auction models with strategic bidding, bargaining, or matching markets. Triggers on "Nash equilibrium", "subgame perfect", "best response", "strategic interaction", "entry game", "conduct testing", "auction", "mechanism design", "matching market", "bargaining", "BNE", "Bayesian Nash", "static game", "dynamic game", "repeated game", "multiple equilibria", "equilibrium selection", "discrete game", "oligopoly", "game-theoretic", "player", "payoff", "strategy", "dominant strategy", "Bresnahan-Reiss", "Ciliberto-Tamer", "partial identification", "set identification", or markup test.
empirical-playbook
by brycewang-stanford
This skill covers applied microeconomic empirical methods and research design. Use when the user is selecting an identification strategy, comparing estimators, running diagnostics, designing a research study, or evaluating an empirical strategy. Triggers on "which method", "what estimator", "how to choose", "method comparison", "empirical strategy", "research design", "applied micro", "identification strategy", "power analysis", "design-based", "model-based", "minimum detectable effect", "specification".
causal-inference
by brycewang-stanford
This skill covers causal inference methods in observational and quasi-experimental settings. Use when the user is implementing, choosing between, or debugging causal identification strategies — including instrumental variables, difference-in-differences, regression discontinuity, synthetic control, or matching estimators. Triggers on "causal effect", "identification strategy", "instrumental variable", "2SLS", "GMM", "difference-in-differences", "DiD", "staggered treatment", "regression discontinuity", "RDD", "synthetic control", "matching", "propensity score", "IPW", "AIPW", "doubly robust", "LATE", "ATT", "ATE", "parallel trends", "exclusion restriction", "first stage", "weak instruments", or "endogeneity".
adversarial-ux-test
by NousResearch
Roleplay the most difficult, tech-resistant user for your product. Browse the app as that persona, find every UX pain point, then filter complaints through a pragmatism layer to separate real problems from noise. Creates actionable tickets from genuine issues only.
dogfood
by NousResearch
"Exploratory QA of web apps: find bugs, evidence, reports."
blackbox
by NousResearch
Delegate coding tasks to Blackbox AI CLI agent. Multi-model agent with built-in judge that runs tasks through multiple LLMs and picks the best result. Requires the blackbox CLI and a Blackbox AI API key.
code-review-testing
by openai
Test authoring guidance