skills

Imperative guidance for the System.Text.Json APIs added in .NET 11: the built-in `JsonNamingPolicy.PascalCase` naming policy, and the strongly-typed `JsonSerializerOptions.GetTypeInfo<T>()` and `JsonSerializerOptions.TryGetTypeInfo<T>(out JsonTypeInfo<T>? info)` metadata accessors. USE FOR: serializing or deserializing JSON in a net11.0-or-later project when you need PascalCase JSON property names without writing a custom naming policy, a strongly-typed `JsonTypeInfo<T>` instead of the non-generic `JsonTypeInfo`, or a no-throw way to probe whether a type's serialization metadata is resolved. DO NOT USE FOR: projects targeting net10.0 or earlier (none of these APIs exist there), JSON libraries other than System.Text.Json (e.g. Newtonsoft.Json), or camelCase / snake_case / kebab-case naming — those policies shipped in earlier releases.

Install a .NET SDK locally for safe preview testing, specific-version pinning, or reproducible team setups — without modifying the system-wide installation. USE FOR: trying .NET previews safely, testing specific SDK versions, installing MAUI or other workloads on a preview, updating or replacing an existing local SDK, creating reproducible team/CI install scripts, configuring global.json paths. DO NOT USE FOR: system-wide SDK installs, .NET hosts older than 10, runtime-only installs, or projects not using SDK-style commands.

Guides migration of .NET Framework Thread.Abort usage to cooperative cancellation in modern .NET. USE FOR: modernizing code that calls Thread.Abort, catching ThreadAbortException, replacing Thread.ResetAbort, replacing Thread.Interrupt for thread termination, resolving PlatformNotSupportedException or SYSLIB0006 after retargeting to .NET 6+, migrating ASP.NET Response.End or Response.Redirect(url, true) which internally call Thread.Abort. DO NOT USE FOR: code that only uses Thread.Join, Thread.Sleep, or Thread.Start without any abort, interrupt, or ThreadAbortException usage — these APIs work identically in modern .NET and need no migration. Also not for projects staying on .NET Framework, or Thread.Abort usage inside third-party libraries you do not control.

Enable nullable reference types in a C# project and systematically resolve all warnings. USE FOR: adopting NRTs in existing codebases, file-by-file or project-wide migration, fixing CS8602/CS8618/CS86xx warnings, annotating APIs for nullability, cleaning up null-forgiving operators, upgrading dependencies with new nullable annotations. DO NOT USE FOR: projects already fully migrated with zero warnings (unless auditing suppressions), fixing a handful of nullable warnings in code that already has NRTs enabled, suppressing warnings without fixing them, C# 7.3 or earlier projects. INVOKES: Get-NullableReadiness.ps1 scanner script.

Migrate a .NET 9 project or solution to .NET 10 and resolve all breaking changes. USE FOR: upgrading TargetFramework from net9.0 to net10.0, fixing build errors after updating the .NET 10 SDK, resolving source and behavioral changes in .NET 10 / C# 14 / ASP.NET Core 10 / EF Core 10, updating Dockerfiles for Debian-to-Ubuntu base images, resolving obsoletion warnings (SYSLIB0058-SYSLIB0062), adapting to SDK/NuGet changes (NU1510, PrunePackageReference), migrating System.Linq.Async to built-in AsyncEnumerable, fixing OpenApi v2 API changes, cryptography renames, and C# 14 compiler changes (field keyword, extension keyword, span overloads). DO NOT USE FOR: .NET Framework migrations, upgrading from .NET 8 or earlier (use migrate-dotnet8-to-dotnet9 first), greenfield .NET 10 projects, or cosmetic modernization. LOADS REFERENCES: csharp-compiler, core-libraries, sdk-msbuild (always); aspnet-core, efcore, cryptography, extensions-hosting, serialization-networking, winforms-wpf, containers-interop (selective).

Migrate a .NET 8 project to .NET 9 and resolve all breaking changes. USE FOR: upgrading TargetFramework from net8.0 to net9.0, fixing build errors after updating the .NET 9 SDK, resolving behavioral changes in .NET 9 / C# 13 / ASP.NET Core 9 / EF Core 9, replacing BinaryFormatter (now always throws), resolving SYSLIB0054-SYSLIB0057, adapting to params span overload resolution, fixing C# 13 compiler changes, updating HttpClientFactory for SocketsHttpHandler, and resolving EF Core 9 migration/Cosmos DB changes. DO NOT USE FOR: .NET Framework migrations, upgrading from .NET 7 or earlier, greenfield .NET 9 projects, or cosmetic modernization unrelated to the upgrade.

Migrate a .NET 10 project or solution to .NET 11 and resolve all breaking changes. This is a MIGRATION skill — use it when upgrading from .NET 10 to .NET 11, NOT for writing new programs. USE FOR: upgrading TargetFramework from net10.0 to net11.0, fixing build errors after updating the .NET 11 SDK, resolving source-breaking and behavioral changes in .NET 11 runtime, C# 15 compiler, and EF Core 11, adapting to updated minimum hardware requirements (x86-64-v2, Arm64 LSE), and updating CI/CD pipelines and Dockerfiles for .NET 11. DO NOT USE FOR: .NET Framework migrations, upgrading from .NET 9 or earlier, greenfield .NET 11 projects, or cosmetic modernization unrelated to the upgrade. NOTE: .NET 11 is in preview. Covers breaking changes through Preview 3.

Make .NET projects compatible with Native AOT and trimming by systematically resolving IL trim/AOT analyzer warnings. USE FOR: making projects AOT-compatible, fixing trimming warnings, resolving IL warnings (IL2026, IL2070, IL2067, IL2072, IL3050), adding DynamicallyAccessedMembers annotations, enabling IsAotCompatible. DO NOT USE FOR: publishing native AOT binaries, optimizing binary size, replacing reflection-heavy libraries with alternatives. INVOKES: no tools — pure knowledge skill.

Fix, modernize, review, or explain supplied MSTest code and MSTest-specific configuration while honoring installed versions and project style. ALWAYS USE for direct corrections: expected/actual order; generic/manual assertions; exception, hard-cast, or object[] patterns; TestContext/lifecycle; timeout/cancellation; condition/retry/cleanup; parallelization; MSTest.Sdk setup; or MSTESTxxxx. Use for "review" only when corrected code or edits are wanted. DO NOT USE for new test-case design (code-testing-agent), report-only audits/metrics (test-anti-patterns or assertion-quality), creating/wiring a first test project (scaffold-dotnet-test-project), running tests, migration, non-MSTest frameworks, or non-.NET.

Analyzes test suites in any language and tags each test with standardized traits (positive, negative, critical-path, boundary, smoke, regression, integration, performance, security). Use when the user wants to categorize, audit, or label tests with traits. Works across .NET (MSTest/xUnit/NUnit/TUnit), Python (pytest), TS/JS (Jest/Vitest), Java, Go, Ruby, Rust, Swift, Kotlin, PowerShell, and C++ — auto-editing when the framework has canonical tag syntax, otherwise report-only. Do not use for writing new tests, running tests, or migrating frameworks.

Audits existing tests in any language using formal, research-backed test smell names and the testsmells.org 19-smell academic taxonomy. Use when the caller asks for an academic or citable test-smell review, named smell categories, or a formal severity-ranked smell assessment. Covers Assertion Roulette, Conditional Test Logic, Mystery Guest, Eager Test, Sleepy Test, Unknown Test, Sensitive Equality, and the rest of the catalog across .NET, Python, JavaScript/TypeScript, Java, Go, Ruby, Rust, Swift, Kotlin, PowerShell, and C++. DO NOT USE FOR a quick pragmatic test review (use test-anti-patterns), writing or running tests, framework migration, coverage, or assertion-diversity metrics.

Find or close verified gaps in existing tests. USE FOR: "add missing edge cases", "would tests catch this bug?", weak tests, survived boundaries/guards/ errors, or pseudo-mutation analysis. Polyglot. DO NOT USE FOR: a new suite (code-testing-agent), smells/assertion audits, or an actual mutation tool.

Audit an existing test file or suite and produce a severity-ranked diagnostic report. ALWAYS USE for findings about tests that verify nothing, missing or tautological assertions, swallowed/broad exceptions, flaky or order-dependent tests, duplication, or magic values. Polyglot. DO NOT USE for direct edits: use writing-mstest-tests for supplied MSTest assertions, attributes, or lifecycle, and code-testing-agent for new tests. Do not use for running tests, migration, assertion metrics (assertion-quality), coverage/CRAP metrics, or the testsmells.org catalog (test-smell-detection).

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).

Run or recommend the exact .NET test command. ALWAYS USE when asked to run, filter, or troubleshoot .NET tests or provide precise flags/argument order. Supports SDK-style dotnet test and classic non-SDK projects using MSBuild plus vstest.console/MSTest or repository scripts. USE FOR: all tests or subsets by class/category/trait; multi-TFM --framework; TRX reports; crash/hang dumps; VSTest vs Microsoft.Testing.Platform; bridged vs native MTP argument syntax; --filter, --filter-class, --filter-trait, --filter-query, and --treenode-filter. Detects MSTest/xUnit/NUnit/TUnit and packages.config/classic project constraints. DO NOT USE FOR: writing tests (use code-testing-agent), MTP hot-reload iteration, CI/CD configuration, or debugging test logic.

Detect a .NET project's test platform/framework and SDK-style vs classic project system. ALWAYS USE for "which test platform/framework?", "VSTest or MTP?", a wrong dotnet test runner, or hidden runner settings in global.json, .csproj, packages.config, Directory.Build.props, or Directory.Packages.props. Handles SDK-version precedence and MSTest/xUnit/NUnit/TUnit. DO NOT USE for running/filtering tests (run-tests), hot reload, or migration.

Suggests using Microsoft Testing Platform (MTP) hot reload to iterate fixes on failing tests without rebuilding. Use when user says "hot reload tests", "iterate on test fix", "run tests without rebuilding", "speed up test loop", "fix test faster", or needs to set up MTP hot reload to rapidly iterate on test failures. Covers setup (NuGet package, environment variable, launchSettings.json) and the iterative workflow for fixing tests. DO NOT USE FOR: writing test code, diagnosing test failures, running tests normally with dotnet test (use run-tests), applying test filters, producing TRX reports, CI/CD pipeline configuration, or Visual Studio Test Explorer hot reload (which is a different feature).

Replace existing static dependency call sites with a wrapper or built-in abstraction that already exists or is registered in DI, across a bounded scope (file, project, namespace). USE FOR: replace DateTime.UtcNow/DateTime.Now with TimeProvider and add the constructor parameter, migrate static call sites to a wrapper already in DI, bulk replace File.* with IFileSystem, scoped migration of statics in only certain files, update unit tests to a fake time source, make an existing static or utility class testable by adding an ambient TimeProvider/IFileSystem seam while every current call site keeps compiling, behavior-preserving time refactors that must keep the same DateTimeKind. DO NOT USE FOR: detecting statics (use detect-static-dependencies), designing a brand-new wrapper interface that does not exist yet (use generate-testability-wrappers), migrating between test frameworks.

Grades a specified set of test methods individually and produces a concise table mapping each test (fully-qualified name) to a letter grade (A–F), a score band, and a one-line note — designed to be posted as a PR comment. Use when the caller wants per-test feedback on a curated list of methods (for example, the new or modified tests in a pull request), not a suite-wide audit. Polyglot: .NET, Python, TS/JS, Java, Go, Ruby, Rust, Swift, Kotlin, PowerShell, C++. Input is a list of test methods (or method bodies / file+line spans); output is a compact markdown table plus a short summary. DO NOT USE FOR: full suite audits (use test-quality-auditor agent or test-anti-patterns), writing new tests (use code-testing-generator agent or writing-mstest-tests), fixing failures, or measuring code coverage.

Generate wrapper interfaces and DI registration for hard-to-test static dependencies in C#, when the abstraction does NOT exist yet. Produces IFileSystem, IEnvironmentProvider, IConsole, IProcessRunner wrappers, or guides first-time adoption of TimeProvider and IHttpClientFactory. With no DI container, produces the ambient context seam instead. USE FOR: generate wrapper for static, create IFileSystem wrapper, wrap DateTime.Now, make a static or a class testable, create abstraction for File.*, generate DI registration, adopt TimeProvider when it is not registered yet, IHttpClientFactory setup, testability wrapper, how to make statics injectable, adopt System.IO.Abstractions, make code testable without adding a DI framework. DO NOT USE FOR: detecting statics (use detect-static-dependencies), migrating call sites or replacing existing DateTime.*/File.* usages once the wrapper is created or already registered in DI (use migrate-static-to-wrapper), general interface design.

MANDATORY for static requests to find, identify, or list untested source files or modules, sources without tests, source-to-test pairing, test-gap worklists, or suggested test locations. Invoke even for a tiny package; do not substitute manual globbing. Uses Roslyn for C#/.NET and tree-sitter for Python, TS/JS, Go, Java, Rust, and Ruby. DO NOT USE FOR: line/branch coverage, CRAP risk, or grading existing tests.

Reference data for test filter syntax across all platform and framework combinations: VSTest --filter expressions, MTP filters for MSTest/NUnit/xUnit v3/TUnit, and VSTest-to-MTP filter translation. DO NOT USE directly — loaded by run-tests, mtp-hot-reload, and migrate-vstest-to-mtp when they need filter syntax.

Scan C# source files for hard-to-test static dependencies — DateTime.Now/UtcNow, File.*, Directory.*, Environment.*, HttpClient, Console.*, Process.*, and other untestable statics. Produces a ranked report of static call sites by frequency. USE FOR: find untestable statics, scan for static dependencies, testability audit, identify hard-to-mock code, find DateTime.Now usage, detect static coupling, testability report, static analysis for testability. DO NOT USE FOR: generating wrappers (use generate-testability-wrappers), migrating code (use migrate-static-to-wrapper), general code review, or finding statics that are already behind abstractions.

Calculates targeted CRAP (Change Risk Anti-Patterns) scores for a named .NET method, class, or single source file. Use when the user explicitly asks to compute CRAP scores or assess risky untested code for a specific target, combining Cobertura coverage data with cyclomatic complexity analysis. DO NOT USE FOR: project-wide coverage analysis, coverage plateau or "stuck coverage" diagnosis, what's blocking coverage, or where to add tests across a project (use coverage-analysis); writing tests; running tests without CRAP context.

Project-wide code coverage and CRAP (Change Risk Anti-Patterns) score analysis for .NET projects. Calculates CRAP scores per method and surfaces risk hotspots — complex code with low coverage that is dangerous to modify. Use to diagnose why coverage is stuck or plateaued, identify what methods block improvement, or get project-wide coverage analysis with risk ranking. USE FOR: coverage stuck, coverage plateau, can't increase coverage, what's blocking coverage, coverage gap, CRAP scores, risk hotspots, where to add tests, coverage analysis, coverage report. DO NOT USE FOR: targeted single-method CRAP analysis (use crap-score); auditing test code for coverage-touching or other anti-patterns (use test-anti-patterns); writing tests; running tests (use run-tests). Requires or produces coverage (Cobertura) and CRAP metrics.