Testing Claude Skills
3 543 testing skills from 425 authors. They run test suites, check accessibility and catch what broke. Half of them fit into 1 799 tokens or less — that is what one costs your context window when the agent loads it. 404 ship runnable scripts rather than instructions alone. 2 of them cannot work without an MCP server, most often rube. We also found 429 copies of these same skills sitting in other people's repositories — counted once here, not 429 times.
3 543 unique 425 authors 2 updated this month 331 from vendors
Guides pytest test suite architecture and coverage strategy for Python 3.11+ projects. Activates when designing test architecture, planning test pyramid distribution, choosing between unit/integration/property-based/BDD strategies, structuring fixture hierarchies, configuring branch coverage thresholds, or applying mutation testing to critical code paths.
Pytest testing patterns for Python — fixtures (session/module/function/factory), AAA structure, behavioral naming, coverage targets by code type, property-based testing with Hypothesis, and mutation testing with mutmut. Use when writing tests, designing fixtures, configuring coverage, or applying parametrize, async testing, or property-based strategies.
Shared Python 3.11+ development standards covering type safety (ty, native generics, Protocol, TypeIs), layered architecture, error handling, performance, identifier naming, UI/CLI patterns (Rich/Typer), testing requirements (pytest, 80% coverage, TDD), and quality gates. Activates when any Python skill or agent needs to apply shared standards for implementation, code review, refactoring, or test authoring.
Establishes a dual-hypothesis investigation mindset for every test failure — treating failures as diagnostic signals that may indicate a real bug OR an incorrect test, never defaulting to automatic code changes or test dismissal. Use when encountering failing tests, debugging test errors, running a test suite that shows regressions, or any request involving "test failure analysis", "why is this test failing", or "should I fix the test or the code". Loads a 5-step protocol covering failure reading, implementation tracing, requirement context, reasoned decision-making, and learning extraction. Works alongside analyze-test-failures for detailed per-failure analysis and comprehensive-test-review for full suite review.
Use when building terminal UI apps with the Textual framework — creating widgets, screens, layouts, handling events, managing reactive attributes, testing with Pilot, snapshot testing with pytest-textual-snapshot, or running background workers. Covers App lifecycle, CSS styling, screen stack, custom messages, actions, bindings, and the Worker API.
Use when building or debugging Typer/Rich CLI applications. Activates on Rich table rendering, console output in non-TTY environments, CliRunner testing with Rich output, snapshot testing, Typer command wiring, exception chain prevention with AppExit/AppExitRich patterns, table width at 80-column wrapping, Progress/Live in non-interactive contexts, stderr/stdout separation, or force_terminal vs width configuration. Grounds AI-generated CLI code in verified correctness patterns and prevents known Typer/Rich integration mistakes.
Use when building CLI applications with Typer — creating commands, defining arguments and options with enum restrictions, path validation, date and UUID types, composing subcommands, testing with CliRunner, or using advanced features like colored output, progress bars, shell autocompletion, and version callbacks.
Use when analyzing failing test cases to determine whether failures indicate genuine bugs or test implementation issues. Activates on "analyze failing tests", "debug test failures", "investigate test errors", or when provided with specific failing test names or output. Applies balanced investigative reasoning — does not auto-fix tests without establishing root cause.
Use when reviewing pytest test suites for coverage, isolation, mock usage, naming conventions, or completeness. Activates on requests like "review test coverage", "audit test quality", or "check tests for completeness". Performs thorough checklist-driven review for test isolation, mock correctness, AAA pattern adherence, and naming standards.
Guided workflow for adding new features to Python projects. Use when planning a new feature implementation, when adding functionality with proper test coverage, or when following TDD to build features incrementally.
Use when building Python 3.11+ CLI apps (Typer/Rich), writing pytest test suites, fixing ruff linting or ty/mypy type errors, configuring pyproject.toml, creating portable scripts, or reviewing Python code. Activates on all Python implementation tasks — routes to specialist agents for CLI architecture, test design, packaging, and code review. Authoritative reference for modern Python 3.11-3.14 patterns and TDD workflows.
Use when designing pytest test suite architecture, planning test coverage strategy, or reviewing test structure for Python 3.11+ projects. Activates on "design a test strategy", "plan test coverage", "create test architecture", or when TDD/BDD/property-based testing patterns are mentioned. Guides fixture design, parametrization, async testing, and mutation testing coverage decisions.
Use when encountering failing tests, diagnosing test errors, or establishing a systematic approach to test failure investigation. Activates on "test failure analysis", "debugging tests", or "why tests fail" requests. Establishes the mindset that treats test failures as valuable diagnostic signals requiring root-cause investigation — not automatic code fixes or test dismissal.
Use when building Textual TUI apps — creating widgets, laying out screens, handling events, managing reactivity, testing with Pilot, or running background workers. Covers App lifecycle, CSS styling, screen stack, reactive attributes, custom messages, actions, bindings, and the Worker API.
Use when building Typer/Rich CLI applications or reviewing existing CLI code for correctness. Activates on requests involving Rich table rendering, console output handling, testing Rich-formatted output, or Typer command wiring. Prevents common AI mistakes — Rich table wrapping in non-TTY contexts, incorrect stderr/stdout separation, and integration pitfalls. Load alongside the typer and rich API reference skills.
Use when building CLI applications with Typer — creating commands, defining arguments and options, composing subcommands, testing with CliRunner, or using advanced features like callbacks and autocompletion. Covers app creation, parameter types, subcommand composition, testing patterns, and output utilities.
Use when debugging software, investigating incidents, diagnosing flaky tests, or analyzing performance regressions — enforces structured observation recording with evidence IDs, causality validation, and verification gates to prevent correlation-causation pollution. Use when an agent might otherwise summarize or speculate instead of reporting observed evidence.
| Building robust R packages with modern tidyverse patterns. Use this skill when creating or maintaining R packages, designing APIs, choosing dependencies, implementing input validation, writing error messages, or deciding between internal and exported functions. Covers dependency strategy, tidyverse API design patterns, validation approaches, error handling with cli/rlang, testing levels, and documentation priorities.
| Type-stable vector operations and custom vector classes using vctrs. Use this skill when building R packages with custom types, need guaranteed output types regardless of input values, implementing consistent coercion/casting rules, or creating vector classes that work seamlessly with data frames. Covers when to use vctrs vs base R, building custom vector classes, coercion methods, and testing vctrs classes.
Use when diagnosing and fixing bugs in a Kotlin Multiplatform project. Focus on root-cause analysis, minimal safe fixes, KMP correctness, UI/state/data/persistence/concurrency issues, and regression prevention.
Use when designing, implementing, or reviewing tests in KMP projects — unit tests, instrumented tests, Compose Multiplatform UI tests, test doubles, test strategy, stability, performance, and screenshot testing.
Perform mutation testing on the codebase. Introduces deliberate bugs one at a time, checks whether the test suite catches each one, and reports on test suite gaps. Optionally implements missing tests.
Use when validating the Mathodology skills-only repository or preserving archived knowledge about the former development, testing, deployment, packaging, and release workflows.
Use when running Mathodology award-workflow phase gates, judge panels, structured handoffs, figure QA, or rendered-PDF QA in a contest run.
Laravel 13 queue and job patterns — driver choice, job design (idempotency, ShouldQueue, model serialisation), retry and failure handling, worker scaling, Bus batching and chaining, Horizon when warranted, queue testing. Use when designing async jobs, scheduling background work, configuring Horizon, debugging stuck jobs, or auditing queue health. Triggers on "Laravel queue", "Laravel job", "background job", "Horizon setup", "failed jobs", "Bus batch", "queue worker tuning".
End-to-end testing with Playwright for web applications. Use when writing E2E tests, browser automation, form submission testing, or user flow testing. Triggers on "playwright", "e2e test", "browser test", "end-to-end", "form flow testing", or test files in tests/e2e/.
Laravel 13 testing with Pest PHP 4 or PHPUnit 12. Use when writing feature tests, unit tests, or any test code in a Laravel application. Triggers on tasks involving HTTP tests, model factories, database assertions, mocking facades, authentication testing, or test organisation patterns.
Unit testing, integration testing, and test-driven development principles. Use when writing tests, reviewing test code, improving test coverage, or setting up testing strategy. Triggers on "write tests", "review tests", "testing best practices", or "TDD".
Host-based simulation using the Zephyr native_sim board. Covers building for Linux/macOS/Windows, automated testing, host-side debugging (GDB, Valgrind), and host-target integration. Trigger when developing application logic without hardware or setting up CI/CD tests.
Testing and debugging for Zephyr RTOS. Covers the Ztest framework for unit and integration tests, the Twister test runner for automated HIL/SIM validation, and advanced tracing/debugging techniques (SystemView, Thread Analyzer, Stack analysis). Trigger when writing unit tests, setting up CI/CD pipelines, or analyzing system performance and latency.
Use when working a mission or slice: the SDLC flow (intent -> mini-requirements + proof contract -> mockups -> plan-lock -> build -> QA -> `rig proof` drops -> proof-lock), and how to track, prove, and hand off state across agents and compaction via PROGRESS.md / PROOF.md / MISSION_NOTES.md. Covers the two locks, role contracts, hot-potato queue handoff, and the `rig scope audit` backstop.
Create UI mockups at three fidelity levels — ASCII wireframes for quick iteration, standalone HTML mockups for delivery with requirements, and live prototypes for interaction testing.
How the development pod coordinates implementation, QA, and design without skipping gates.
Systematically explore and test a web application to find bugs, UX issues, and other problems. Use when asked to "dogfood", "QA", "exploratory test", "find issues", "bug hunt", "test this app/site/platform", or review the quality of a web application. Produces a structured report with full reproduction evidence -- step-by-step screenshots, repro videos, and detailed repro steps for every issue -- so findings can be handed directly to the responsible teams.
Use when about to claim work is complete, fixed, or passing, before committing or creating PRs - requires running verification commands and confirming output before making any success claims; evidence before assertions always
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes
[AUTO-INVOKE] MUST be invoked BEFORE writing or modifying any test files (*.t.sol). Covers test structure, naming conventions, coverage requirements, fuzz testing, and Foundry cheatcodes. Trigger: any task involving creating, editing, or running Solidity tests.
Patterns for building entity actors with Akka.Hosting - GenericChildPerEntityParent, message extractors, cluster sharding abstraction, akka-reminders, and ITimeProvider. Supports both local testing and clustered production modes.
Write unit and integration tests for Akka.NET actors using modern Akka.Hosting.TestKit patterns. Covers dependency injection, TestProbes, persistence testing, and actor interaction verification. Includes guidance on when to use traditional TestKit.
Write integration tests using .NET Aspire's testing facilities with xUnit. Covers test fixtures, distributed application setup, endpoint discovery, and patterns for testing ASP.NET Core apps with real dependencies.
Write UI tests for Blazor applications (Server or WebAssembly) using Playwright. Covers navigation, interaction, authentication, selectors, and common Blazor-specific patterns.
Use Verify for snapshot testing in .NET. Approve API surfaces, HTTP responses, rendered emails, and serialized outputs. Detect unintended changes through human-reviewed baseline files.
Write integration tests using TestContainers for .NET with xUnit. Covers infrastructure testing with real databases, message queues, and caches in Docker containers instead of mocks.
Snapshot test email templates using Verify to catch regressions. Validates rendered HTML output matches approved baseline. Works with MJML templates and any email renderer.
Expert guidance for Swift Testing: test structure, #expect/#require macros, traits and tags, parameterized tests, test plans, parallel execution, async waiting patterns, and XCTest migration. Use when writing new Swift tests, modernizing XCTest suites, debugging flaky tests, or improving test quality and maintainability in Apple-platform or Swift server projects.
End-to-end testing specialist using Playwright. Use PROACTIVELY for generating, maintaining, and running E2E tests. Manages test journeys, quarantines flaky tests, uploads artifacts (screenshots, videos, traces), and ensures critical user flows work.
Use this skill when writing new features, fixing bugs, or refactoring code. Enforces test-driven development with 80%+ coverage including unit, integration, and E2E tests.
Use when implementing app integrity verification, preventing fraud with DCAppAttestService, validating requests from legitimate app instances, using DeviceCheck for promotional abuse prevention, or needing server-side attestation/assertion validation. Covers key generation, attestation, assertion, rollout strategy, and risk metrics.