.NET Skills is an AI coding plugin that provides skills and specialized guidance for professional .NET development, covering areas such as C#, Akka.NET, Aspire, Entity Framework Core, testing, and performance. .NET developers use it with coding assistants to apply production-oriented patterns while building and maintaining applications. The catalogue contains the plugin’s skills, agents, and instructions.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add Aaronontheweb/dotnet-skills --skill testcontainersgit clone --depth 1 https://github.com/Aaronontheweb/dotnet-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/aaronontheweb/dotnet-skills/testcontainers)<a href="https://agentmods.dev/skills/aaronontheweb/dotnet-skills/testcontainers"><img src="https://agentmods.dev/badge/skills/aaronontheweb/dotnet-skills/testcontainers/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/aaronontheweb/dotnet-skills/testcontainers"><img src="https://agentmods.dev/badge/skills/aaronontheweb/dotnet-skills/testcontainers.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Prompt Injection · line 124 Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00038 | $0.02170 |
| Opus 5.5 | $0.00015 | $0.00868 |
| Sonnet 5.5 | $0.00008 | $0.00434 |
| Haiku 4.5 | $0.00004 | $0.00217 |
Grade A, and why
testcontainers-integration-tests scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
Copies of this mod
1 near-identical copy found in the catalogue:
- testcontainers-integration-tests — 100% identical, 86 lines differ
How it starts
The opening of the file, as written. The whole thing — 273 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Integration Testing with TestContainers
When to Use This Skill
Use this skill when:
- Writing integration tests that need real infrastructure (databases, caches, message queues)
- Testing data access layers against actual databases
- Verifying message queue integrations
- Testing Redis caching behavior
- Avoiding mocks for infrastructure components
- Ensuring tests work against production-like environments
- Testing database migrations and schema changes
Reference Files
- database-patterns.md: SQL Server, PostgreSQL, and migration testing examples
- infrastructure-patterns.md: Redis, RabbitMQ, multi-container networks, container reuse, and Respawn
Core Principles
- Real Infrastructure Over Mocks - Use actual databases/services in containers, not mocks
- Test Isolation - Each test gets fresh containers or fresh data
- Automatic Cleanup - TestContainers handles container lifecycle and cleanup
- Fast Startup - Reuse containers across tests in the same class when appropriate
- CI/CD Compatible - Works seamlessly in Docker-enabled CI environments
- Port Randomization - Containers use random ports to avoid conflicts
TestContainers 4.x API
This skill targets TestContainers 4.x with the 3.0+ module builder API. The pre-3.0 types were renamed and removed, so code that uses TestcontainersBuilder<T> or TestcontainersContainer does not compile against the modern packages:
| Old (pre-3.0) | New (3.0+) |
|---|---|
new TestcontainersBuilder<T>() |
Module builder (e.g. new PostgreSqlBuilder(...)) or new ContainerBuilder(...) |
TestcontainersContainer |
DockerContainer / module container (e.g. PostgreSqlContainer) |
TestcontainersNetworkBuilder |
NetworkBuilder |
GetMappedPublicPort(port) |
GetMappedPublicPort(port) (still available) |
Why 4.x and not 3.x? The module builders did not expose image-taking constructors in Testcontainers 3.0.0. Those constructors (and the deprecation of the parameterless builder constructor) arrived in the 4.x line, so the examples here rely on 4.x behavior. Pin the module packages to a 4.x (or newer) version rather than an unbounded wildcard if you want reproducible builds.
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 11d ago Changed · +47 lines 5bb27b4cc58a
- 12d ago Changed 928ac09398c0
- 1mo ago First seen · 226 lines · 38 tokens per session scan A 6cd442fcf432
testcontainers-integration-tests is a skill published in the GitHub repository Aaronontheweb/dotnet-skills (1,235 stars, last pushed 10d ago), licensed MIT. It adds 38 tokens to every session and 2,170 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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