# Mcp Csharp Test

> >

- **Type:** Skill
- **Install:** `agentstack add skill-dotnet-skills-mcp-csharp-test`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [dotnet](https://agentstack.voostack.com/s/dotnet)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [dotnet](https://github.com/dotnet)
- **Source:** https://github.com/dotnet/skills/tree/main/plugins/dotnet-ai/skills/mcp-csharp-test

## Install

```sh
agentstack add skill-dotnet-skills-mcp-csharp-test
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# C# MCP Server Testing

Test MCP servers at two levels: unit tests for individual tool methods, and integration tests that exercise the full MCP protocol in-memory.

## When to Use

- Adding automated tests to an MCP server
- Testing individual tool methods with mocked dependencies
- Writing integration tests that validate tool listing and invocation via MCP protocol
- Setting up CI test pipelines for MCP servers

## Stop Signals

- **No server yet?** → Use `mcp-csharp-create` first
- **Server not running?** → Use `mcp-csharp-debug`
- **Just need manual/interactive testing?** → Use `mcp-csharp-debug` for MCP Inspector

## Inputs

| Input | Required | Description |
|-------|----------|-------------|
| MCP server project path | Yes | Path to the server `.csproj` being tested |
| Test framework | Recommended | Default: xUnit. Also supports NUnit or MSTest |
| Transport type | Recommended | Determines integration test approach (stdio vs HTTP) |

## Workflow

### Step 1: Create the test project

```bash
dotnet new xunit -n .Tests
cd .Tests
dotnet add reference ..//.csproj
dotnet add package ModelContextProtocol
dotnet add package Moq
dotnet add package FluentAssertions
```

### Step 2: Write unit tests for tool methods

Test tool methods directly — fastest and most isolated:

```csharp
public class MyToolTests
{
    [Fact]
    public void Echo_ReturnsFormattedMessage()
    {
        var result = MyTools.Echo("Hello");
        result.Should().Be("Echo: Hello");
    }

    [Theory]
    [InlineData("")]
    [InlineData("   ")]
    public void Echo_HandlesEdgeCases(string input)
    {
        var result = MyTools.Echo(input);
        result.Should().StartWith("Echo:");
    }
}
```

For tools with DI dependencies, mock the dependency:
```csharp
public class ApiToolTests
{
    [Fact]
    public async Task FetchData_ReturnsApiResponse()
    {
        var handler = new MockHttpMessageHandler("""{"id": 1}""");
        var httpClient = new HttpClient(handler);

        var result = await ApiTools.FetchData(httpClient, "resource-1");
        result.Should().Contain("id");
    }
}
```

### Step 3: Write integration tests with MCP client

Test the full MCP protocol using a client-server connection:

```csharp
using ModelContextProtocol.Client;

public class ServerIntegrationTests : IAsyncLifetime
{
    private McpClient _client = null!;

    public async Task InitializeAsync()
    {
        var transport = new StdioClientTransport(new StdioClientTransportOptions
        {
            Name = "TestClient",
            Command = "dotnet",
            Arguments = ["run", "--project", "..//.csproj"]
        });
        _client = await McpClient.CreateAsync(transport);
    }

    public async Task DisposeAsync() => await _client.DisposeAsync();

    [Fact]
    public async Task Server_ListsExpectedTools()
    {
        var tools = await _client.ListToolsAsync();
        tools.Should().Contain(t => t.Name == "echo");
    }

    [Fact]
    public async Task Tool_ReturnsExpectedResult()
    {
        var result = await _client.CallToolAsync("echo",
            new Dictionary { ["message"] = "Test" });
        var text = result.Content.OfType().First().Text;
        text.Should().Contain("Test");
    }
}
```

**For the SDK's `ClientServerTestBase` (in-memory testing) and HTTP testing with `WebApplicationFactory`**, see [references/test-patterns.md](references/test-patterns.md).

### Step 4: Run tests

```bash
# Run all tests
dotnet test

# Run a specific test class
dotnet test --filter "FullyQualifiedName~MyToolTests"

# Run with coverage
dotnet test --collect:"XPlat Code Coverage"
```

### Step 5: Write evaluations

Evaluations measure how well an LLM uses your tools. Good evaluation questions should be:
- **Read-only and non-destructive** — never modify data as a side effect
- **Deterministic** — have a single verifiable correct answer
- **Multi-step** — require the LLM to call multiple tools or reason across results

For the evaluation format, example questions, and detailed guidance, see [references/evaluations.md](references/evaluations.md).

## Validation

- [ ] Unit tests cover all tool methods, including edge cases
- [ ] Integration tests verify tool listing via `ListToolsAsync()`
- [ ] Integration tests verify tool invocation via `CallToolAsync()`
- [ ] All tests pass: `dotnet test`
- [ ] Tests run in CI without manual setup

## Common Pitfalls

| Pitfall | Solution |
|---------|----------|
| Integration test hangs on `CreateAsync` | Server fails to start. Verify `dotnet build` succeeds first. For stdio, ensure no stdout logging |
| `StdioClientTransport` not finding project | Use the correct relative path to `.csproj` from the test project directory |
| Tests pass locally but fail in CI | Run `dotnet build` before test execution. Use `--no-build` only after an explicit build step |
| Mocking `HttpClient` is awkward | Mock `HttpMessageHandler`, not `HttpClient` directly. See [references/test-patterns.md](references/test-patterns.md) |
| Full test suite runs are slow | Use `--filter` for development. Run the full suite only for CI verification |

## Related Skills

- `mcp-csharp-create` — Create a new MCP server project
- `mcp-csharp-debug` — Running and interactive debugging
- `mcp-csharp-publish` — NuGet, Docker, Azure deployment

## Reference Files

- [references/test-patterns.md](references/test-patterns.md) — Complete test code examples: `ClientServerTestBase` in-memory pattern, `WebApplicationFactory` for HTTP, `MockHttpMessageHandler` helper, test categorization, coverage reporting. **Load when:** writing integration tests or need detailed mock patterns.
- [references/evaluations.md](references/evaluations.md) — Evaluation format, question design principles, and example eval questions. **Load when:** user asks about evaluations, eval questions, or measuring tool quality.

## More Info

- [xUnit documentation](https://xunit.net/docs/getting-started/netcore/cmdline) — Getting started with xUnit for .NET

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [dotnet](https://github.com/dotnet)
- **Source:** [dotnet/skills](https://github.com/dotnet/skills)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-dotnet-skills-mcp-csharp-test
- Seller: https://agentstack.voostack.com/s/dotnet
- Browse the marketplace: https://agentstack.voostack.com/browse

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