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Find working code samples, verify API signatures, and fix Microsoft SDK errors using official docs. Use whenever the user is writing, debugging, or reviewing code that touches any Microsoft SDK, .NET library, Azure client library, or Microsoft API—even if they don't ask for a "reference." Catches hallucinated methods, wrong signatures, and deprecated patterns. If the task involves producing or fixing Microsoft-related code, this is the right skill.

Understand Microsoft technologies by querying official documentation. Use whenever the user asks how something works, wants tutorials, needs configuration options, limits, quotas, or best practices for any Microsoft technology (Azure, .NET, M365, Windows, Power Platform, etc.)—even if they don't mention "docs." If the question is about understanding a concept rather than writing code, this is the right skill.

Analyzes the variety and depth of assertions across test suites in any language. Use when the user asks to evaluate assertion quality, find shallow tests, identify assertion-free tests (no assertions or only trivial ones like Assert.IsNotNull / toBeTruthy()), flag self-referential or tautological assertions, measure assertion diversity, or audit whether tests verify different facets of behavior. Polyglot: .NET, Python, TS/JS, Java, Go, Ruby, Rust, Swift, Kotlin, PowerShell, C++. DO NOT USE FOR: writing new tests (use code-testing-agent / writing-mstest-tests), mutation reasoning about whether tests would catch a bug (use test-gap-analysis), or a general severity-ranked anti-pattern audit (use test-anti-patterns), fixing or rewriting assertions, or writing, fixing, or modernizing MSTest tests, assertions, or attributes (use writing-mstest-tests).

Reference data for .NET test framework detection patterns, assertion APIs, skip annotations, setup/teardown methods, and common test smell indicators across MSTest, xUnit, NUnit, and TUnit. Loaded by test analysis skills (test-anti-patterns) as framework-specific lookup tables.

Parse-only static analysis that pairs source files with the tests referencing them and emits JSON listing untested files ordered by API surface, each with a suggested_test_path. Roslyn engine for C#/.NET (namespace-aware), tree-sitter engine for polyglot repos (Python, TS/JS, Go, Java, Rust, Ruby). USE FOR: where to write tests next, which files have no tests, find untested code, build a source-to-test pairing map, prioritized test-gap worklist. DO NOT USE FOR: line/branch coverage or CRAP risk (use coverage-analysis); whether existing tests are strong (use test-gap-analysis or assertion-quality).

Mechanically replace static dependency call sites with wrapper or built-in abstraction calls across a bounded scope (file, project, or namespace). Performs codemod-style bulk replacement of DateTime.UtcNow to TimeProvider.GetUtcNow(), File.ReadAllText to IFileSystem, and similar transformations. Adds constructor injection parameters and updates DI registration. USE FOR: replace DateTime.Now/UtcNow with TimeProvider, migrate static calls to wrapper, bulk replace File.* with IFileSystem, codemod static to injectable, add constructor injection for a dependency, mechanical or scoped migration of statics, convert static calls to use an abstraction, update call sites. DO NOT USE FOR: detecting statics (use detect-static-dependencies), generating wrappers (use generate-testability-wrappers), migrating between test frameworks.

Run, filter, or troubleshoot .NET tests with `dotnet test`. USE FOR: running all tests in a project or solution; running only a subset (a specific test class, category, or trait) via filters; running a single target framework in a multi-TFM project (`--framework`); producing TRX reports; collecting crash or hang dumps; diagnosing why `dotnet test` fails or uses the wrong argument syntax. Detects the test platform (VSTest vs Microsoft.Testing.Platform) and framework (MSTest/xUnit/NUnit/TUnit), then picks the matching command: the `--` separator on .NET SDK 8/9 vs 10+, the right filter flag (--filter, --filter-class, --filter-trait, --filter-query, --treenode-filter), and TRX/blame flags. DO NOT USE FOR: writing test code (use code-testing-agent), iterating on failing tests without rebuilding (use mtp-hot-reload), CI/CD config, or debugging test logic.

Provides file paths to language-specific reference files for the test ANALYSIS skills (assertion-quality, test-anti-patterns, test-gap-analysis, test-smell-detection, test-tagging). Call this skill to discover available extension files (e.g., dotnet.md for .NET/MSTest/xUnit/NUnit/TUnit, python.md for pytest/unittest, typescript.md for Jest/Vitest/Mocha, java.md for JUnit/TestNG, etc.). Do not use directly — invoked by the test-quality-auditor agent and polyglot analysis skills that need framework-specific lookup tables (test markers, assertion APIs, skip annotations, sleep patterns, mystery guest indicators, integration markers, setup/teardown, tag-support capability).

Write, create, modernize, or fix comprehensive MSTest unit tests with MSTest 3.x/4.x APIs. USE FOR: write or create MSTest unit tests, fix/modernize MSTest assertions, better MSTest assertion than Assert.IsTrue, replace hard cast with type check (IsInstanceOfType), MSTest assertion APIs (Contains, ContainsSingle, HasCount, IsEmpty, IsNotEmpty, DoesNotContain, AreSame, IsNull, StartsWith, EndsWith, MatchesRegex, IsGreaterThan, IsLessThan, IsInRange), swapped Assert.AreEqual args, replace ExpectedException with Assert.Throws, data-driven (DataRow, DynamicData, ValueTuples), lifecycle (TestInitialize, TestCleanup, TestContext), async tests and cancellation tokens, conditional execution/retry/cleanup (OSCondition, Retry), parallelization (Parallelize/DoNotParallelize), MSTest.Sdk setup, MSTESTxxxx analyzer fixes. DO NOT USE FOR: test quality audits (use test-anti-patterns), running tests (use run-tests), MSTest version migration (use the migrate-mstest skills), xUnit/NUnit/TUnit, or non-.NET languages.