Akka.NET Testing Patterns

What it does

When your agent uses it

• Writing unit tests for Akka.NET actors that take injected services
• Testing persistent actors and their recovery from stored events
• Checking message flows between actors with TestProbes
• Deciding between Akka.Hosting.TestKit and the traditional TestKit

Example prompts

• “Write tests for my OrderActor using Akka.Hosting.TestKit and a fake payment service.”
• “Add a persistence test showing the cart actor restores its state after a restart.”
• “Should this console app use the traditional Akka.TestKit or Akka.Hosting.TestKit?”

Requirements

• A .NET project using Akka.NET v1.5 or later with Akka.Hosting

Workflow steps

8 steps, taken from the first numbered list in SKILL.md.

1. 1Inherit from Akka.Hosting.TestKit.TestKit - This is a framework base class, not a user-defined one
2. 2Override ConfigureServices() - Replace real services with fakes/mocks
3. 3Override ConfigureAkka() - Configure actors using the same extension methods as production
4. 4Use ActorRegistry - Type-safe retrieval of actor references
5. 5Composition over Inheritance - Fake services as fields, not base classes
6. 6No Custom Base Classes - Use method overrides, not inheritance hierarchies
7. 7Test One Actor at a Time - Use TestProbes for dependencies
8. 8Match Production Patterns - Same extension methods, different AkkaExecutionMode

What it can do on your machine

Read from SKILL.md and the folder at commit e426ed9. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are csharp and xml).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Akka.NET Testing Patterns loads about 2.4k tokens when it runs. Until then it costs about 69 tokens; SKILL.md has 785 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~69

When it runs · the whole SKILL.md, loaded when a task matches

~2.4k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from Aaronontheweb/dotnet-skills at commit e426ed9, republished under its MIT licence (© Aaronontheweb). 785 words, ~2,442 tokens.

name

akka-net-testing-patterns

description

Write unit and integration tests for Akka.NET actors using modern Akka.Hosting.TestKit patterns. Covers dependency injection, TestProbes, persistence testing, and actor interaction verification. Includes guidance on when to use traditional TestKit.

invocable

false

<ItemGroup>
  <!-- Core testing framework -->
  <PackageReference Include="Akka.Hosting.TestKit" Version="*" />

  <!-- xUnit (or your preferred test framework) -->
  <PackageReference Include="xunit" Version="*" />
  <PackageReference Include="xunit.runner.visualstudio" Version="*" />
  <PackageReference Include="Microsoft.NET.Test.Sdk" Version="*" />

  <!-- Assertions (recommended) -->
  <PackageReference Include="FluentAssertions" Version="*" />

  <!-- In-memory persistence for testing -->
  <PackageReference Include="Akka.Persistence.Hosting" Version="*" />

  <!-- If testing cluster sharding -->
  <PackageReference Include="Akka.Cluster.Hosting" Version="*" />
</ItemGroup>

// TestEnvironmentInitializer.cs
using System.Runtime.CompilerServices;

namespace YourApp.Tests;

internal static class TestEnvironmentInitializer
{
    [ModuleInitializer]
    internal static void Initialize()
    {
        // Disable config file watching in test hosts
        // Prevents file descriptor exhaustion (inotify watch limit) on Linux
        Environment.SetEnvironmentVariable("DOTNET_HOSTBUILDER__RELOADCONFIGONCHANGE", "false");
    }
}

public class OrderActorTests : TestKit
{
    private readonly FakeOrderRepository _fakeRepository = new();

    protected override void ConfigureServices(HostBuilderContext context, IServiceCollection services)
    {
        services.AddSingleton<IOrderRepository>(_fakeRepository);
    }

    protected override void ConfigureAkka(AkkaConfigurationBuilder builder, IServiceProvider provider)
    {
        builder.WithInMemoryJournal().WithInMemorySnapshotStore();
        builder.WithActors((system, registry, resolver) =>
        {
            registry.Register<OrderActor>(system.ActorOf(resolver.Props<OrderActor>(), "order-actor"));
        });
    }

    [Fact]
    public async Task CreateOrder_Success_SavesToRepository()
    {
        var orderActor = ActorRegistry.Get<OrderActor>();
        var response = await orderActor.Ask<OrderCommandResult>(
            new CreateOrder("ORDER-123", "CUST-456", 99.99m), RemainingOrDefault);
        response.Status.Should().Be(CommandStatus.Success);
        _fakeRepository.SaveCallCount.Should().Be(1);
    }
}

protected override void ConfigureAkka(AkkaConfigurationBuilder builder, IServiceProvider provider)
{
    builder
        .AddDraftSerializer()                                    // Same as production
        .AddOrderDomainActors(AkkaExecutionMode.LocalTest)      // Same, but local mode
        .WithInMemoryJournal().WithInMemorySnapshotStore();      // Test-specific overrides
}

await AwaitAssertAsync(() =>
{
    _fakeReadModelService.SyncCallCount.Should().BeGreaterOrEqualTo(1);
}, TimeSpan.FromSeconds(3));

// Constructor with debug logging
public OrderActorTests(ITestOutputHelper output)
    : base(output: output, logLevel: LogLevel.Debug)
{
}

© Aaronontheweb, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files in skills/akka-testing-patterns of Aaronontheweb/dotnet-skills.

• SKILL.md
• anti-patterns-and-reference.md
• examples.md

Open the folder on GitHubat commit e426ed9

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in Aaronontheweb/dotnet-skills, which our catalogue first saw on October 7, 2026.

• NeverSight/learn-skills.devdata/skills-md/aaronontheweb/dotnet-skills/akka-net-testing-patterns