Universal testing framework (frontend + backend) — a meticulous run of any testing task with evidence discipline. Use when you need to test a feature/form/build/API/service, draft a test plan, run checks, perform exploratory or regression testing, or find defects.
Write, review, and debug tests using Vitest. Use for: unit tests, API route tests, executor/serializer/tool tests, jsdom vs node environment selection, shared __test-utils__ patterns, and mandatory code-to-test sync with executed test runs.
When the user wants to plan, design, or implement an A/B test or experiment, or build a growth experimentation program. Also use when the user mentions "A/B test," "split test," "experiment," "test this change," "variant copy," "multivariate test," "hypothesis," "should I test this," "which version is better," "test two versions," "statistical significance," "how long should I run this test," "growth experiments," "experiment velocity," "experiment backlog," "ICE score," "experimentation program," or "experiment playbook." Use this whenever someone is comparing two approaches and wants to measure which performs better, or when they want to build a systematic experimentation practice. For tracking implementation, see analytics. For page-level conversion optimization, see cro.
Test user-facing UI with TDD, component tests, a11y checks, and critical-path coverage. Use when writing or fixing UI tests, verifying loading/error/empty states, or when the user mentions test/TDD/coverage/regresi — including natural language, not only /test-ui.
How DAG nodes prove code changes through public interfaces - red before green for new behavior and bug fixes, preservation checks for refactors, and mocks at system boundaries - loaded through load_skills.
Validate and choose proportionate test proof for tests, CI, coverage, evals, and closeout evidence: map changed files to repo-native commands, place checks at commit, push, and pull-request gates, classify pass/fail/blocked ownership, and preserve trace/regression artifacts. Use when users ask what tests or gates to run, how to design coverage, why validation failed, or what proof supports a claim.
Write tests for E2BGateway. Use when writing unit tests, integration tests, or E2E tests — covers conventions, layer selection, mocks, and race detection.
Write tests for code. Use when: (1) user asks to write, add, or improve tests; (2) after implementing non-trivial features—propose which tests would add value before writing; (3) user asks to verify a bugfix with a regression test; (4) user wants to understand what tests a change needs.
Design or review testing strategy, test portfolios, and test quality. Use for unit/integration/contract/E2E choices, flaky or brittle tests, mocks and test doubles, BDD review, legacy-code testing, production QA, and testing LLM or AI-generated systems. Also covers TCRDD / TCR (test && commit || revert, red-green-refactor, baby steps, commit on green, revert on failure, approval-gated TDD) and HTTP API smoke tests (smoke test, critical path test, CI gate, Hurl, .hurl files, curl smoke test).
What makes a good test, whatever is under test, from choosing inputs and oracles to judging how adequate a suite is. Use to design, write, plan, or review any kind of test or test plan, including flaky tests, or on /testing.
Write, change, or review Fast Link tests, choose between specs, browser tests, and real app fixtures, or audit and clean up test suites. Use when assessing test value, duplication, reliability, or coverage in this repository.
A folder with a SKILL.md file: a name, a description of when to use it, and instructions. Claude loads a skill only when the task matches its description.
How do I use one I find here?
Copy the folder into your project's .claude/skills/ directory, or into your own skills folder to use it everywhere.
What do the warnings mean?
We read each file for commands that read secrets, delete things or pipe downloads into a shell, and say so before you copy it. No warning is not a promise that a file is safe.
Which skills worked for people?
Open a skill to see its discussion. Reports from people and their agents are coming.