.NET Test
S-rankRun, diagnose, and migrate .NET tests: test execution, filtering, platform detection, MSTest workflows, coverage analysis, anti-patterns, and migrations across xUnit/MSTest versions.
Install This Skill
/plugin install dotnet-test@dotnet-agent-skills# Download SKILL.md and place in your agent's skills folder
curl -o SKILL.md https://github.com/dotnet/skills/tree/main/plugins/dotnet-test/raw/main/SKILL.md/skill add dotnet/dotnet-testSkill bundle — 23 sub-skills
upstream is a skill bundleThis catalog entry is a skill bundle that ships 23 individual SKILL.md files. Each one is listed below — click through to read the full markdown on GitHub.
assertion-quality
Analyzes the variety and depth of assertions across test suites in any language. Use when the user asks to evaluate assertion quality, find shallow testing, identify assertion-free tests (no assertions or only trivial ones like Assert.IsNotNull / expect(x).toBeTruthy() / assert x is not None), flag self-referential or tautological assertions (output equals input on identity/round-trip operations), measure assertion coverage diversity, or audit whether tests verify different facets of correctness. Produces metrics and actionable recommendations. Polyglot: .NET (MSTest/xUnit/NUnit/TUnit), Python (pytest/unittest), TS/JS (Jest/Vitest/Mocha/Jasmine/node:test), Java (JUnit/TestNG), Go, Ruby (RSpec/Minitest), Rust, Swift (XCTest/Swift Testing), Kotlin (JUnit/Kotest), PowerShell (Pester), C++ (GoogleTest/Catch2/doctest). DO NOT USE FOR: writing new tests (use code-testing-agent, or writing-mstest-tests for MSTest), anti-patterns like flakiness or duplication (use test-anti-patterns), fixing assertions.
plugins/dotnet-test/skills/assertion-qualitycode-testing-agent
>- Generates and writes new unit tests for any programming language using a Research-Plan-Implement pipeline. Use when asked to generate tests, write unit tests, add tests, improve test coverage, create test project, achieve high coverage, comprehensive tests, or asked to scaffold a new test project for an app, service, or library. Supports C#, TypeScript, JavaScript, Python, Go, Rust, Java, and more. Orchestrates the code-testing-generator sub-agent through research, planning, and implementation phases so tests compile, pass, and follow project conventions. DO NOT USE FOR: running existing tests or test filters (use run-tests); diagnosing coverage plateaus or project-wide coverage/CRAP analysis without writing tests (use coverage-analysis); targeted method/class CRAP scores (use crap-score); MSTest assertion guidance, MSTest test pattern modernization, or fixing existing MSTest test code (use writing-mstest-tests).
plugins/dotnet-test/skills/code-testing-agentcode-testing-extensions
>- Provides file paths to language-specific extension files for the code-testing pipeline. Call this skill to discover available extension guidance files (e.g., dotnet.md for .NET, cpp.md for C++). Do not use directly — invoked by code-testing agents and skills that need language-specific references.
plugins/dotnet-test/skills/code-testing-extensionscoverage-analysis
> 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), writing tests, running tests without coverage, or troubleshooting test execution (use run-tests).
plugins/dotnet-test/skills/coverage-analysiscrap-score
> 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.
plugins/dotnet-test/skills/crap-scoredetect-static-dependencies
> 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.
plugins/dotnet-test/skills/detect-static-dependenciesdotnet-test-frameworks
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.
plugins/dotnet-test/skills/dotnet-test-frameworksfilter-syntax
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.
plugins/dotnet-test/skills/filter-syntaxgenerate-testability-wrappers
> Generate wrapper interfaces and DI registration for hard-to-test static dependencies in C#. Produces IFileSystem, IEnvironmentProvider, IConsole, IProcessRunner wrappers, or guides adoption of TimeProvider and IHttpClientFactory. USE FOR: generate wrapper for static, create IFileSystem wrapper, wrap DateTime.Now, make static testable, make class testable, create abstraction for File.*, generate DI registration, TimeProvider adoption, IHttpClientFactory setup, testability wrapper, mock-friendly interface, mock time in tests, create the right abstraction to mock, how to mock DateTime, test code using File.ReadAllText, what abstraction for Environment, how to make statics injectable, adopt System.IO.Abstractions, make file calls testable. DO NOT USE FOR: detecting statics (use detect-static-dependencies), migrating call sites (use migrate-static-to-wrapper), general interface design not about testability.
plugins/dotnet-test/skills/generate-testability-wrappersmigrate-mstest-v1v2-to-v3
> Migrate MSTest v1 or v2 test project to MSTest v3. Use when user says "upgrade MSTest", "upgrade to MSTest v3", "migrate to MSTest v3", "update test framework", "modernize tests", "MSTest v3 migration", "MSTest compatibility", "MSTest v2 to v3", or build errors after updating MSTest packages from 1.x/2.x to 3.x. USE FOR: upgrading from MSTest v1 assembly references (Microsoft.VisualStudio.QualityTools.UnitTestFramework) or MSTest v2 NuGet (MSTest.TestFramework 1.x-2.x) to MSTest v3, fixing assertion overload errors (AreEqual/AreNotEqual), updating DataRow constructors, replacing .testsettings with .runsettings, timeout behavior changes, target framework compatibility (.NET 5 dropped -- use .NET 6+; .NET Fx older than 4.6.2 dropped), adopting MSTest.Sdk. First step toward MSTest v4 -- after this, use migrate-mstest-v3-to-v4. DO NOT USE FOR: migrating to MSTest v4 (use migrate-mstest-v3-to-v4), migrating between frameworks (MSTest to xUnit/NUnit), or general .NET upgrades unrelated to MSTest.
plugins/dotnet-test/skills/migrate-mstest-v1v2-to-v3migrate-mstest-v3-to-v4
> Fix build errors and breaking changes after upgrading MSTest from v3 to v4, or plan a complete MSTest v3-to-v4 migration. Use when user says "upgrade to MSTest v4", "MSTest 4 migration", "MSTest v4 breaking changes", "tests don't compile after upgrading MSTest", or has errors CS0507, CS0103, CS1061, CS1615 after updating MSTest packages from 3.x to 4.x. USE FOR: Execute to ExecuteAsync, CallerInfo constructor on TestMethodAttribute, sealed custom attributes, ClassCleanupBehavior removal, TestContext.Properties Contains to ContainsKey, Assert.ThrowsException to ThrowsExactly, Assert.IsInstanceOfType out parameter removal, ExpectedExceptionAttribute removal, TestTimeout enum removal, [TestMethod("name")] to DisplayName syntax, TreatDiscoveryWarningsAsErrors, TestContext.TestName in ClassInitialize, MSTest.Sdk MTP changes, dropped TFMs (net6.0/net7.0 to net8.0+). DO NOT USE FOR: migrating from MSTest v1/v2 to v3 (use migrate-mstest-v1v2-to-v3 first), migrating between test frameworks, or general .NET upgrades.
plugins/dotnet-test/skills/migrate-mstest-v3-to-v4migrate-static-to-wrapper
> 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.UtcNow with TimeProvider, replace DateTime.Now with TimeProvider, migrate static calls to wrapper, bulk replace File.* with IFileSystem, codemod static to injectable, add constructor injection for time provider, mechanical migration of statics, refactor DateTime to TimeProvider, swap static for injected dependency, convert static calls to use abstraction, replace statics in a class, migrate one file to TimeProvider, scoped migration, update call sites. DO NOT USE FOR: detecting statics (use detect-static-dependencies), generating wrappers (use generate-testability-wrappers), migrating between test frameworks.
plugins/dotnet-test/skills/migrate-static-to-wrappermigrate-vstest-to-mtp
> Migrates .NET test projects from VSTest to Microsoft.Testing.Platform (MTP). Use when user asks to "migrate to MTP", "switch from VSTest", "enable Microsoft.Testing.Platform", "use MTP runner", or mentions EnableMSTestRunner, EnableNUnitRunner, or UseMicrosoftTestingPlatformRunner. USE FOR: MTP behavioral differences vs VSTest (exit code 8, zero tests discovered, --ignore-exit-code, TESTINGPLATFORM_EXITCODE_IGNORE), conditioning OutputType=Exe to test projects when centralizing MTP properties in Directory.Build.props. Supports MSTest, NUnit, xUnit.net v2 (via YTest.MTP.XUnit2), and xUnit.net v3 (native MTP). Covers runner enablement, CLI argument translation, xUnit.net v3 filter migration (--filter-class, --filter-trait, --filter-query), Directory.Build.props and global.json config, CI/CD pipeline updates, and MTP extension packages. DO NOT USE FOR: migrating between test frameworks (MSTest/xUnit/NUnit), xUnit.net v2 to v3 API migration, MSTest version upgrades, TFM upgrades, or UWP/WinUI test projects.
plugins/dotnet-test/skills/migrate-vstest-to-mtpmigrate-xunit-to-xunit-v3
> Migrates .NET test projects from xUnit.net v2 to xUnit.net v3. USE FOR: upgrading xunit to xunit.v3. DO NOT USE FOR: migrating between test frameworks (MSTest/NUnit to xUnit.net), migrating from VSTest to Microsoft.Testing.Platform (use migrate-vstest-to-mtp). For xUnit v3 MTP filter syntax (--filter-class, --filter-trait, --filter-query), also load migrate-vstest-to-mtp.
plugins/dotnet-test/skills/migrate-xunit-to-xunit-v3mtp-hot-reload
> 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).
plugins/dotnet-test/skills/mtp-hot-reloadplatform-detection
Reference data for detecting the test platform (VSTest vs Microsoft.Testing.Platform) and test framework (MSTest, xUnit, NUnit, TUnit) from project files. DO NOT USE directly — loaded by run-tests, mtp-hot-reload, and migrate-vstest-to-mtp when they need detection logic.
plugins/dotnet-test/skills/platform-detectionrun-tests
> For `dotnet test`: figures out which test platform (VSTest vs Microsoft.Testing.Platform) a project uses from `Directory.Build.props`, `global.json`, and `.csproj`, then picks the matching command syntax. USE FOR: running, filtering, or troubleshooting `dotnet test`; identifying the test runner/platform from project files; `--` separator rules on .NET SDK 8/9 vs 10+; choosing the right filter syntax for MSTest / xUnit / NUnit / TUnit (--filter, --filter-class, --filter-trait, --filter-query, --treenode-filter); TRX/reporting (--report-trx vs --logger trx); blame/hang/crash diagnostics (--blame-hang-timeout, --blame-crash); running tests against a single target framework when a project targets multiple TFMs (e.g., `<TargetFrameworks>net8.0;net9.0</TargetFrameworks>`, `--framework <TFM>`); and avoiding MTP/VSTest argument mixups (--logger trx on MTP, --report-trx on VSTest, --blame on MTP). DO NOT USE FOR: writing/generating test code, CI/CD config, or debugging failing test logic.
plugins/dotnet-test/skills/run-teststest-analysis-extensions
>- 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).
plugins/dotnet-test/skills/test-analysis-extensionstest-anti-patterns
> Audits existing test code in any language for anti-patterns and quality issues — produces a severity-ranked report (Critical / Warning / Info) with concrete code-level fixes. Polyglot: .NET (MSTest/xUnit/NUnit/ TUnit), Python (pytest/unittest), TS/JS (Jest/Vitest/Mocha/node:test), Java (JUnit/TestNG), Go, Ruby (RSpec/Minitest), Rust, Swift, Kotlin (JUnit/Kotest), PowerShell (Pester), C++ (GoogleTest/Catch2). INVOKE when asked to audit, review, rank, or find problems in existing tests — "audit my tests", "test smell audit", "rank by severity", tests that pass but verify nothing, no/missing assertions, swallowed exceptions, always-true / self-comparing / tautological assertions, broad exception types, flakiness (sleep/Date.now/time.sleep), ordering dependency, shared global state, duplicated tests, magic values, missing await on async assertions. DO NOT USE FOR: writing new tests (use code-testing-agent, or writing-mstest-tests for MSTest); running tests (use run-tests); framework migration.
plugins/dotnet-test/skills/test-anti-patternstest-gap-analysis
Performs pseudo-mutation analysis on production code in any language to find gaps in existing test suites. Use when the user asks to find weak tests, discover untested edge cases, check if tests would catch a bug, or evaluate test effectiveness through mutation-style reasoning. Analyzes production code for mutation points (boundaries, boolean flips, null/None/nil returns, exception/error removal, arithmetic changes) and checks whether tests would detect each mutation. Polyglot: .NET (MSTest/xUnit/NUnit/TUnit), Python (pytest/unittest), TS/JS (Jest/Vitest/Mocha/node:test), Java (JUnit/TestNG), Go, Ruby (RSpec/Minitest), Rust, Swift, Kotlin (JUnit/Kotest), PowerShell (Pester), C++ (GoogleTest/Catch2). DO NOT USE FOR: writing new tests (use code-testing-agent, or writing-mstest-tests for MSTest), detecting anti-patterns (use test-anti-patterns), measuring assertion diversity (use assertion-quality), or running actual mutation testing tools (Stryker, mutmut, PIT, cargo-mutants).
plugins/dotnet-test/skills/test-gap-analysistest-smell-detection
> Deep-dive audit using the full testsmells.org 19-smell academic catalog for tests in any language. Every finding maps to a named, citable smell from the research literature (Assertion Roulette, Duplicate Assert, Mystery Guest, Eager Test, Sensitive Equality, Conditional Test Logic, Sleepy Test, Magic Number Test, etc.) with research-backed severity. Polyglot: .NET (MSTest/xUnit/NUnit/TUnit), Python (pytest/unittest), TS/JS (Jest/Vitest/Mocha/node:test), Java (JUnit/TestNG), Go, Ruby (RSpec/Minitest), Rust, Swift, Kotlin (JUnit/Kotest), PowerShell (Pester), C++ (GoogleTest/Catch2). INVOKE ONLY when explicitly asked for the testsmells.org 19-smell academic catalog or citable smell names from the literature. DO NOT USE FOR: general or pragmatic audits — use test-anti-patterns; writing new tests (use code-testing-agent, or writing-mstest-tests for MSTest); running tests (use run-tests); framework migration.
plugins/dotnet-test/skills/test-smell-detectiontest-tagging
Analyzes test suites in any language and tags each test with a standardized set of 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 with .NET (MSTest TestCategory / xUnit Trait / NUnit Category / TUnit Property), Python (pytest markers; unittest has no canonical tag syntax so report-only), TypeScript/JavaScript (Jest/Vitest test names, describe-block conventions), Java (JUnit 5 @Tag / TestNG groups), Go (subtest naming / build tags / file _test.go), Ruby (RSpec metadata), Rust (cargo test naming / cfg attributes), Swift (XCTest test plans / Swift Testing @Tag), Kotlin (JUnit @Tag / Kotest tags), PowerShell (Pester -Tag), C++ (GoogleTest filter prefixes / Catch2 [tags] / doctest decorators). Auto-edits when the framework has canonical syntax; falls back to report-only otherwise. Do not use for writing new tests, running tests, or migrating frameworks.
plugins/dotnet-test/skills/test-taggingwriting-mstest-tests
> Write new MSTest unit tests and fix existing MSTest code using MSTest 3.x/4.x modern APIs and best practices. USE FOR: write or create MSTest unit tests, fix or modernize MSTest assertions, better MSTest assertion than Assert.IsTrue, replace hard cast with MSTest type assertion, MSTest assertion APIs (IsInstanceOfType, Contains, ContainsSingle, HasCount, IsEmpty, IsNotEmpty, DoesNotContain, StartsWith, EndsWith, MatchesRegex, IsGreaterThan, IsInRange, IsNull), fix swapped Assert.AreEqual arguments, replace ExpectedException with Assert.Throws, data-driven tests (DataRow, DynamicData, ValueTuples), test lifecycle (sealed classes, TestInitialize, TestCleanup), async tests and cancellation tokens, test parallelization (Parallelize / DoNotParallelize), MSTest.Sdk project setup. DO NOT USE FOR: broad test quality audits (use test-anti-patterns), running tests (use run-tests), MSTest version migration (use migrate-mstest-v1v2-to-v3 or migrate-mstest-v3-to-v4), xUnit/NUnit/TUnit, or non-.NET languages.
plugins/dotnet-test/skills/writing-mstest-testsQuick Stats
Source repo · this pathAuthor
.NET Foundation
@dotnet