Server mode

MTP server mode lets an editor, IDE, or other test tool launch a test application and drive discovery and execution through JSON-RPC. Use server mode when you build tooling around MTP. For normal command-line and CI runs, run the test application directly or use dotnet test.

Start the public JSON-RPC server with --server or --server jsonrpc.

Use the source-only client

Starting with MTP 2.4.0, the Microsoft.Testing.Platform.ServerMode.Client.Sources package supplies a canonical client for the JSON-RPC protocol. The package injects C# source into your project instead of adding a runtime assembly.

The source-only design provides:

• No runtime DLL or additional deployment dependency.
• Native AOT-compatible, reflection-free serialization.
• Protocol types and serialization code from the same repository as the MTP server.

The injected MtpServerClient and IMtpServerClient types can initialize a connection, discover tests, run tests, request server exit, and report test-node updates. The types remain internal to your assembly.

Meet client requirements

Use C# 12 or later. The package sets LangVersion to 12.0 when your project doesn't specify a language version. It also supplies internal compatibility types for .NET Framework 4.6.2 and netstandard2.0.

Remove any hand-written copy of the MTP client before you add the package to avoid duplicate internal types.

Choose connection behavior

Set MtpServerClientOptions.IsStateful to tell the server whether the client preserves state across requests:

• Leave the value false for a single discovery or execution request followed by exit.
• Set the value to true for an editor or IDE session that sends multiple requests over the same connection.

The client sends this setting through the experimental capabilities.testing.isStateful protocol capability.

See also

• Run and debug tests with MTP
• Build a test framework for MTP
• MTP JSON-RPC protocol