Sets up visual regression coverage for a Storybook project - either via the official @chromatic-com/storybook addon (hosted) or via @storybook/test-runner with a postVisit hook that calls Playwright's toHaveScreenshot (self-hosted). Covers test-runner install, lifecycle hooks (setup / preVisit / postVisit), and CI integration. Use when a repo already has a working `.storybook/` config and the team wants per-story visual coverage rather than page-level snapshots.

Produces a single breakpoint-matrix report (rows = pages/stories, columns = viewports) across Percy, Chromatic, Playwright snapshots, or Storybook test-runner. Routes per-engine viewport syntax, runs each, and aggregates the results into one cross-breakpoint view. Use when the team needs one unified pass/fail view across three or more viewport widths instead of separate per-engine or per-breakpoint reports. The matrix-view output is the distinguishing trait: it dispatches to playwright-snapshots (and the other engines) rather than replacing any single-engine skill.

Authors Percy visual snapshot tests via the @percy/cli + framework SDK (Playwright, Cypress, Selenium, Storybook), runs them with `percy exec -- {test command}`, configures viewports / masking / ignored regions, and reviews diffs in the Percy build UI. Use when the project ships visual regression coverage to BrowserStack Percy.

Configures and runs pytest - the de facto Python test framework with fixture-based dependency injection (`@pytest.fixture` with scopes module/session/function), parametrize for table-driven tests (`@pytest.mark.parametrize`), markers (`@pytest.mark.skip` / `xfail` / `slow`), `conftest.py` for shared fixtures, plugin ecosystem (pytest-cov, pytest-asyncio, pytest-mock, pytest-xdist), `--lf`/`--ff` for fail-loop, coverage gating. Use when working with Python and needing the modern test framework.

Configures and runs xUnit.net (xUnit v2 + v3) - current de facto .NET test framework with `[Fact]` for single tests + `[Theory]` + `[InlineData]`/`[ClassData]`/`[MemberData]` for parametrized; collection fixtures (`[Collection]`) + class fixtures (`IClassFixture`) for shared setup; output via `ITestOutputHelper`; parallel test config via assembly attribute. Use when working with .NET (C# / F# / VB.NET) on the modern test stack.

Configures and runs NUnit - JVM-style attribute-driven .NET test framework with `[Test]` / `[TestCase]` / `[TestCaseSource]` / `[Values]` / `[Random]` parametrize attributes; `[SetUp]` / `[TearDown]` / `[OneTimeSetUp]` / `[OneTimeTearDown]` lifecycle; categories for selective runs; constraint-model assertion API (`Assert.That(actual, Is.EqualTo(expected))`); parameterized fixtures via `[TestFixture]` typed args. Use when working with .NET on a NUnit codebase or preferring constraint-model assertions over xUnit's classic style.

Configures and runs MSTest (now MSTest.TestFramework v3) - Microsoft's first-party .NET test framework with `[TestClass]` / `[TestMethod]` / `[DataRow]` / `[DynamicData]` attributes; `[ClassInitialize]` / `[ClassCleanup]` / `[TestInitialize]` / `[TestCleanup]` lifecycle; `TestContext` injection; tight Visual Studio + dotnet test integration. Use when working with .NET on a MSTest codebase, or in environments standardized on Microsoft toolchain.

Configures and runs ScalaTest - Scala-native test framework with multiple specification styles (FlatSpec, FunSuite, WordSpec, FreeSpec, AsyncFlatSpec for async); Matchers DSL (`should equal`, `should contain`, `shouldBe a [Class]`); integrates with ScalaCheck for property-based testing; sbt + Maven + Gradle support; tagged-test selective execution. Use when working with Scala codebases.

Configures and runs Jest - Meta-built batteries-included JS/TS unit framework with built-in `expect`, snapshot testing, mocking (`jest.mock`, `jest.fn`, `jest.spyOn`, manual `__mocks__/`), test environment selection (`jsdom` / `node`), parallel workers, coverage via Istanbul, watch mode, and CI integration via `--ci` flag. Use when the user works with React (CRA / older Next.js) or Node services and needs the most ecosystem-supported JS test framework.

Configures and runs Jasmine - the original BDD-style JS test framework (predecessor to Jest) with built-in matchers + spies, no external assertion library; ships `jasmine-core` + `jasmine` runner; `spec_dir` + `helpers` convention; `jasmine.json` config; spy patterns (`spyOn`, `createSpy`); pairs with Karma for in-browser testing. Use when the user maintains legacy AngularJS / Karma+Jasmine codebases, or wants minimal BDD-style tests with no third-party assertion library.

Configures and runs Go's stdlib `testing` package - `func TestXxx(t *testing.T)` convention; table-driven tests via slice + range; `t.Run` for subtests with hierarchical names; `t.Parallel()` for parallel execution; benchmarks (`func BenchmarkXxx(b *testing.B)`); examples (`func ExampleXxx()`); fuzzing (`func FuzzXxx(f *testing.F)`); coverage via `go test -cover`/`-coverprofile`; build tags for selective compilation. Use for any Go project - testing is a stdlib feature, no install needed.

Configures and runs Rust's built-in `cargo test` - `#[test]` + `#[should_panic]` + `Result<(), E>` returns; integration tests in `tests/`; doc-tests embedded in `///` comments; `--lib` / `--bins` / `--all-targets` / `--workspace` selection; `cargo bench` (nightly) + Criterion (stable); `cargo test -- --test-threads=1` for serial; `cargo test -- --nocapture` to see println output. Use for any Rust project - testing is built into Cargo, no install needed.

Pure-reference catalog of leap-second mechanics and the bugs they cause: the 23:59:60 UTC insertion (announced ~6 months ahead by IERS Bulletin C; 27 inserted 1972-2016; abolished by 2035 per CGPM 2022), the Google/AWS leap-smear alternative, and the four bug classes a real insertion exposes - time_t non-monotonicity, negative durations, NTP cascading, and cross-node clock skew - each with a monotonic-clock fix and a freezegun simulation. Use when auditing time-sensitive code (financial timestamping, distributed logs, NTP-driven schedulers) for second-by-second progress assumptions; for the far more common daylight-saving-time transition hazards, use dst-transition-reference instead.

Wraps .NET's TimeProvider abstraction (System.TimeProvider, introduced .NET 8) and FakeTimeProvider from Microsoft.Extensions.TimeProvider.Testing: SetUtcNow, Advance, AutoAdvanceAmount, CreateTimer, Delay, and the pre-.NET-8 ISystemClock migration path. Use when testing C# or F# code that reads the current time, uses timers, or awaits Task.Delay.

Audits an existing test automation framework across eight architecture-tier axes and bands each one PASS, WARN, or FAIL: page-object coverage and purity, base-class inheritance depth, fixture scope and coupling, helper sprawl, naming-convention drift, retry and wait consistency, documented-versus-actual convention drift, and CI integration health. Carries the numeric cut behind every band and labels which cuts are practitioner conventions rather than published standards. Measures the framework's own structure (page objects, base classes, fixtures, helpers, conventions), not the suite's tier mix or flake rate, and not the design of a framework that does not exist yet. Use when a test framework has grown for a release or more without structural review, before a major refactor, or when a team suspects its written test conventions no longer match what the code actually does.

Scores test files 1 to 5 on six design axes (AAA phase separation, single-responsibility, naming, fixture coupling, magic literals, setup time) using explicit per-level anchors that settle what separates a 2 from a 4, then turns the scores into growth-framed feedback and a per-author trend report; the per-PR and per-author rollup examples and trend-reporting conventions live in references/. Owns the scoring and the write-up only: the conventions being scored live in a separate conventions catalog such as `test-code-conventions`, and block-or-approve gating belongs to an adversarial review. Use when a test diff needs a graded coaching read rather than a merge verdict: onboarding a new engineer, a team deliberately ramping up test discipline, or a quarterly per-author trend where the output is a conversation, not a gate.

Imports CI test results into Xray for Jira - authenticates via the `client_id` + `client_secret` → JWT exchange (Cloud) or PAT / Basic (Server), posts to the format-specific `/api/v2/import/execution/*` endpoint (`/junit` for JUnit XML, `/cucumber` for Cucumber JSON, `/nunit` / `/testng` / `/robot` for the others), and maps automated results to existing Xray Test issues via the `xray-junit-extensions` `@XrayTest(key="...")` annotation. Use when the team uses the Xray Jira app to manage Test, Test Set, and Test Execution issue types and CI must keep those execution issues in sync; for the other Jira TCM app use zephyr-integration (Zephyr Scale), for standalone non-Jira TestRail use testrail-integration, and for hosted cross-run flakiness analytics rather than TCM sync use currents-integration.

Build-an-X workflow that turns a structured test-run artifact (JUnit XML, Allure JSON, TestRail / Xray / Zephyr export) plus optional release context (version, build URL, deploy target) into a narrative markdown summary for release notes, an exec status update, or a stand-up Slack post. Distinct from the per-framework parsers junit-xml-analysis / allure-reports / coverage-diff-reporter, which emit structured tabular reports: this skill takes the same data and writes the human-readable narrative. Use when a manager needs a draft release note or stand-up summary from a single run; for cross-run trend analytics use currents-integration.

Configures ExtentReports v5 for a JVM (or .NET via `extentreports-dotnet`) test run: wires `ExtentSparkReporter`, `attachReporter`, `createTest`, the `info`/`pass`/`warning`/`skip`/`fail` log chain, screenshots via `MediaEntityBuilder`, hierarchical `createNode` parent/child tests, and category/author/device labels, emitting a static HTML report alongside JUnit XML for CI artifact upload. Use when a suite on the Aventstack ExtentReports stack wants a richer per-test HTML narrative than JUnit XML gives; for code-coverage reporting use jacoco-analysis, and for hosted cross-run flakiness analytics use currents-integration.

Parses Cobertura XML coverage reports (the JVM-canonical format originally from the cobertura-cobertura tool, also emitted by JaCoCo `--coverage-xml`, coverage.py `--xml`, Istanbul / Jest `cobertura` reporter, gocover-cobertura, and dotnet's `coverlet`). Walks the coverage-04 DTD structure (coverage → packages → classes → methods → lines + conditions), computes per-file deltas, and emits PR-time gating verdicts. Use when the existing CI emits Cobertura XML - typical for JVM-heavy stacks and tools that ship Cobertura as a default reporter.