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Found 423 Skills
Use when writing or changing tests, adding mocks, or tempted to add test-only methods to production code - prevents testing mock behavior, production pollution with test-only methods, and mocking without understanding dependencies
Battle-tested testing best practices for AI coding assistants (40+ rules). Use when writing, reviewing, or generating tests. Covers test structure, data factories, assertions, mocking, DOM testing, and database testing. Works with Vitest, Jest, Playwright, Testing Library, Storybook, and more.
Use this skill when writing unit tests with Jest or Vitest, implementing mocking strategies, configuring test runners, or improving test coverage. Triggers on Jest, Vitest, describe/it/expect, mocking, vi.fn, jest.fn, snapshot testing, test coverage, and any task requiring JavaScript/TypeScript unit testing.
Use when you need to review, improve, or write Java unit tests — including migrating from JUnit 4 to JUnit 5, adopting AssertJ for fluent assertions, structuring tests with Given-When-Then, ensuring test independence, applying parameterized tests, mocking dependencies with Mockito, verifying boundary conditions (RIGHT-BICEP, CORRECT, A-TRIP), leveraging JSpecify null-safety annotations, or eliminating testing anti-patterns such as reflection-based tests or shared mutable state. Part of the skills-for-java project
Unit testing patterns for isolated business logic tests — AAA pattern, parametrized tests (test.each, @pytest.mark.parametrize), fixture scoping (function/module/session), mocking with MSW/VCR at network level, and test data management with factories (FactoryBoy, faker-js). Use when writing unit tests, setting up mocks, structuring test data, optimizing test speed, choosing fixture scope, or reducing test boilerplate. Covers Vitest, Jest, pytest.
Use when you need to write fast unit tests for Quarkus applications — including pure tests with @ExtendWith(MockitoExtension.class), @QuarkusTest with @InjectMock for full CDI mock replacement, @InjectSpy for partial CDI bean mocking, REST Assured for resource-focused tests, @ParameterizedTest with @CsvSource / @MethodSource, QuarkusTestProfile for test-specific configuration overrides, and naming conventions (*Test → Surefire, *IT → Failsafe). For framework-agnostic Java use @131-java-testing-unit-testing. Part of the skills-for-java project
Test and troubleshoot Enable Banking sandbox integrations, ASPSP sandbox behavior, Mock ASPSP setup, sandbox credentials, AIS authorization simulation, transaction pagination quirks, and sandbox limitations. Use when Codex needs to choose a sandbox bank, find test credentials, explain why a sandbox ASPSP behaves differently from production, configure Mock ASPSP data, or implement project code that must work against Enable Banking sandbox environments.
TDD London School workflow -- mock-first, outside-in test development
Write Rails tests with RSpec, FactoryBot, and mocking patterns. Use when creating tests, writing specs for models/controllers/requests, setting up test fixtures, or mocking external services.
Use this skill when writing Go tests with stretchr/testify, implementing TDD workflows, creating mocks, or organizing test suites. Covers assert vs require patterns, interface mocking, table-driven tests, and the red-green-refactor cycle.
Write and run Go tests using the built-in testing package with table-driven tests, subtests, and mocking via interfaces. Use when writing Go tests or setting up test infrastructure.
Write behavior-focused tests following Testing Trophy model with real dependencies, avoiding common anti-patterns like testing mocks and polluting production code. Use when writing new tests, reviewing test quality, or improving test coverage.