.Rulesync

Writing async/await code. Task patterns, ConfigureAwait, cancellation, and common agent pitfalls.

Chooses inter-service protocols. REST vs gRPC vs SignalR vs SSE decision matrix, tradeoffs.

Detects API surface changes in CI. PublicApiAnalyzers, Verify snapshots, ApiCompat gating.

Using records, pattern matching, primary constructors, collection expressions. C# 12-15 by TFM.

Chooses documentation tooling. Starlight, Docusaurus, DocFX decision tree, migration paths.

Builds real-time features. SignalR hubs, SSE (.NET 10), JSON-RPC 2.0, gRPC streaming, scaling.

Efficient code navigation using Serena MCP symbol operations instead of text search

Defines baseline C# conventions loaded first -- naming, file layout, style rules.

Creates Roslyn source generators. IIncrementalGenerator, GeneratedRegex, LoggerMessage, STJ.

Code analysis patterns using Serena MCP for architecture validation and pattern detection

Integrates AI/LLM via Microsoft Agent Framework. Agents, workflows, tools, MCP servers, multi-agent orchestration.

Synchronizes threads and protects shared state. lock, SemaphoreSlim, Interlocked, concurrent collections.

Registers and resolves services with MS DI. Keyed services, scopes, decoration, lifetimes.

Using NSubstitute to create test doubles (Mock, Stub, Spy) specialized skill. Used when isolating external dependencies, simulating interface behavior, and validating method calls. Covers Substitute.For, Returns, Received, Throws and complete guidance. Keywords: mock, stub, spy, nsubstitute, mock, test double, test double, IRepository, IService, Substitute.For, Returns, Received, Throws, Arg.Any, Arg.Is, isolate dependencies, simulate external services, dependency injection testing

Complete guide for xUnit test output and logging. Use when you need to implement test output, diagnostic logging, or ILogger alternatives in xUnit tests. Covers ITestOutputHelper injection, AbstractLogger pattern, structured output design. Includes XUnitLogger, CompositeLogger, performance test diagnostic tool implementations. Keywords: ITestOutputHelper, ILogger testing, test output xunit, test output, test logging, AbstractLogger, XUnitLogger, CompositeLogger, testOutputHelper.WriteLine, test diagnostics, logger mock, test log, structured output, Received().Log

Comprehensive AI prompt engineering safety review and improvement prompt. Analyzes prompts for safety, bias, security vulnerabilities, and effectiveness while providing detailed improvement recommendations.

Designs types for performance. struct vs class, sealed, readonly struct, Span/Memory, collections.

Complete guide for code coverage analysis. Use when you need to analyze code coverage, generate coverage reports, or configure CI/CD coverage checks. Covers Coverlet configuration, report generation, metric interpretation, and cyclomatic complexity integration. Includes Fine Code Coverage, VS Code built-in tools, and best practices. Keywords: code coverage, coverage analysis, coverage report, Coverlet, Fine Code Coverage, dotnet-coverage, ReportGenerator, line coverage, branch coverage, cyclomatic complexity, runsettings, cobertura

Enables nullable reference types. Annotation strategies, migration, common agent mistakes.

Complete guide for .NET Aspire Testing integration testing framework. Use when testing .NET Aspire distributed applications, configuring AppHost tests, or migrating from Testcontainers to Aspire testing. Covers DistributedApplicationTestingBuilder, container lifecycle management, multi-service orchestration, Respawn configuration, and time testability design. Keywords: aspire testing, .NET Aspire, DistributedApplicationTestingBuilder, AppHost testing, distributed testing, AspireAppFixture, IAsyncLifetime, ContainerLifetime.Session, cloud-native testing, multi-service integration, Aspire.Hosting.Testing, Respawn

Test naming conventions and best practices specialized skill. Used when naming test methods, improving test readability, and establishing naming standards. Covers three-part naming method, Chinese naming recommendations, test class naming, etc. Keywords: test naming, test naming, naming conventions, naming conventions, three-part naming, three-part naming, method_scenario_expected, method_scenario_expected, how to name tests, test readability, naming best practices, test report, test documentation

Using AwesomeAssertions for fluent and readable test assertion skill. Used when writing clear assertions, comparing objects, validating collections, handling complex comparisons. Covers Should(), BeEquivalentTo(), Contain(), ThrowAsync() and complete API. Keywords: assertions, awesome assertions, fluent assertions, assertion, fluent assertion, Should(), Be(), BeEquivalentTo, Contain, ThrowAsync, NotBeNull, object comparison, collection validation, exception assertion, AwesomeAssertions, FluentAssertions, fluent syntax

Specialized skill for testing FluentValidation validators. Use when you need to create tests for Validator classes, validate business rules, or test error messages. Covers complete FluentValidation.TestHelper usage, ShouldHaveValidationErrorFor, async validation, cross-field logic, etc. Keywords: validator, validation, fluentvalidation, validation testing, UserValidator, CreateOrderValidator, TestHelper, ShouldHaveValidationErrorFor, ShouldNotHaveValidationErrorFor, TestValidate, TestValidateAsync, testing validators, validating business rules

Guide for Private and Internal member testing strategies. Use when you need to test private or internal members, configure InternalsVisibleTo, or evaluate testability design. Covers design-first thinking, reflection testing, strategy pattern refactoring, AbstractLogger pattern, and decision frameworks. Keywords: private method testing, internal testing, InternalsVisibleTo, reflection testing, GetMethod BindingFlags, Meziantou.MSBuild.InternalsVisibleTo, testability design, strategy pattern refactoring, testability

Specialized skill for handling complex object comparison and deep validation. Use when you need to compare deep objects, exclude specific properties, handle circular references, or validate DTOs/Entities. Covers BeEquivalentTo, Excluding, Including, custom comparison rules, etc. Keywords: object comparison, deep comparison, BeEquivalentTo, DTO comparison, Entity validation, excluding properties, circular reference, Excluding, Including, ExcludingNestedObjects, RespectingRuntimeTypes, WithStrictOrdering, ignore timestamp, exclude timestamp

Complete guide for upgrading xUnit 2.9.x to 3.x. Use when upgrading xUnit v2 to v3 or understanding xUnit v3 new features and breaking changes. Covers package updates, async void fixes, IAsyncLifetime adjustments. Includes new features: Assert.Skip, Explicit Tests, Matrix Theory, Assembly Fixtures. Keywords: xunit upgrade, xunit v3, xunit 3.x, xunit migration, xunit upgrade, xunit.v3, OutputType Exe, IAsyncLifetime v3, Assert.Skip, SkipUnless, SkipWhen, Explicit attribute, MatrixTheoryData, AssemblyFixture, breaking changes

Complete guide for Testcontainers NoSQL integration testing. Use when containerized integration testing for MongoDB or Redis. Covers MongoDB document operations, Redis five data structures, Collection Fixture pattern. Includes BSON serialization, index performance testing, data isolation strategy, and container lifecycle management. Keywords: testcontainers mongodb, testcontainers redis, mongodb integration test, redis integration test, nosql testing, MongoDbContainer, RedisContainer, IMongoDatabase, IConnectionMultiplexer, BSON serialization, BsonDocument, document model testing, cache testing, Collection Fixture

Specialized skill for testing time-dependent logic using TimeProvider. Use when testing DateTime, controlling time flow, handling timezone conversions, and testing expiration logic. Covers TimeProvider abstraction, FakeTimeProvider time control, time freezing and fast-forwarding. Keywords: datetime, time testing, TimeProvider, FakeTimeProvider, DateTime.Now, time-dependent, cache expiration, token expiration, Microsoft.Bcl.TimeProvider, GetUtcNow, SetUtcNow, Advance, time freeze, time freezing, time fast-forward

Specialized skill for testing file system operations using System.IO.Abstractions. Use when you need to test File, Directory, Path operations, or simulate file system. Covers IFileSystem, MockFileSystem, file read/write testing, directory operation testing, etc. Keywords: file testing, filesystem, file testing, file system testing, IFileSystem, MockFileSystem, System.IO.Abstractions, File.ReadAllText, File.WriteAllText, Directory.CreateDirectory, Path.Combine, mock file system, file abstraction

Specialized skill for containerized database testing using Testcontainers. Use when testing real database behavior, using SQL Server/PostgreSQL/MySQL containers, testing EF Core/Dapper. Covers container startup, database migrations, test isolation, container sharing. Keywords: testcontainers, container testing, database testing, MsSqlContainer, PostgreSqlContainer, MySqlContainer, EF Core testing, Dapper testing, Testcontainers.MsSql, Testcontainers.PostgreSql, GetConnectionString, IAsyncLifetime, CollectionFixture

Complete guide for ASP.NET Core Web API integration testing. Use when performing integration testing on Web API endpoints or validating ProblemDetails error format. Covers WebApplicationFactory, IExceptionHandler, Testcontainers multi-container orchestration, Flurl URL construction, and AwesomeAssertions HTTP validation. Keywords: webapi integration testing, WebApplicationFactory, asp.net core integration test, webapi integration test, IExceptionHandler, ProblemDetails, ValidationProblemDetails, AwesomeAssertions, Flurl, Respawn, Be201Created, Be400BadRequest, multi-container testing, Collection Fixture, global exception handling