Akka.NET Testing Patterns

When to Use This Skill

Use this skill when:

• Writing unit tests for Akka.NET actors
• Testing persistent actors with event sourcing
• Verifying actor interactions and message flows
• Testing actor supervision and lifecycle
• Mocking external dependencies in actor tests
• Testing cluster sharding behavior locally
• Verifying actor state recovery and persistence

Reference Files

• examples.md: Complete code samples for all testing patterns (Patterns 1-8 plus Reminders)
• anti-patterns-and-reference.md: Anti-patterns, traditional TestKit, CI/CD integration

Choosing Your Testing Approach

Use Akka.Hosting.TestKit (Recommended for 95% of Use Cases)

When:

• Building modern .NET applications with Microsoft.Extensions.DependencyInjection
• Using Akka.Hosting for actor configuration in production
• Need to inject services into actors (IOptions, DbContext, ILogger, HTTP clients, etc.)
• Testing applications that use ASP.NET Core, Worker Services, or .NET Aspire
• Working with modern Akka.NET projects (Akka.NET v1.5+)

Advantages:

• Native dependency injection support - override services with fakes in tests
• Configuration parity with production (same extension methods work in tests)
• Clean separation between actor logic and infrastructure
• Type-safe actor registry for retrieving actors

Use Traditional Akka.TestKit

When:

• Contributing to Akka.NET core library development
• Working in environments without Microsoft.Extensions (console apps, legacy systems)
• Legacy codebases using manual Props creation without DI

See anti-patterns-and-reference.md for traditional TestKit patterns.

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Core Principles (Akka.Hosting.TestKit)