Struct TestClient 

pub struct TestClient { /* private fields */ }

Test client for in-process MCP testing.

Unlike the production Client, this works with MemoryTransport for fast, in-process testing without subprocess spawning.

Example

use fastmcp_rust::testing::prelude::*;

let (router, client_transport, server_transport) = TestServer::builder()
    .with_tool(my_tool)
    .build();

// Run server in background thread
std::thread::spawn(move || {
    // server loop with server_transport
});

// Create test client
let mut client = TestClient::new(client_transport);
client.initialize().unwrap();

// Test operations
let tools = client.list_tools().unwrap();
assert!(!tools.is_empty());

Implementations

impl TestClient

pub fn new(transport: MemoryTransport) -> Self

Creates a new test client with the given transport.

Example

let (client_transport, server_transport) = create_memory_transport_pair();
let client = TestClient::new(client_transport);

pub fn with_cx(transport: MemoryTransport, cx: Cx) -> Self

Creates a new test client with custom Cx.

pub fn with_client_info( self, name: impl Into<String>, version: impl Into<String>, ) -> Self

Sets the client info for initialization.

pub fn with_capabilities(self, capabilities: ClientCapabilities) -> Self

Sets the client capabilities for initialization.

pub fn initialize(&mut self) -> McpResult<InitializeResult>

Performs the MCP initialization handshake.

Must be called before any other operations.

Errors

Returns an error if the initialization fails.

pub fn is_initialized(&self) -> bool

Returns whether the client has been initialized.

pub fn server_info(&self) -> Option<&ServerInfo>

Returns the server info after initialization.

pub fn server_capabilities(&self) -> Option<&ServerCapabilities>

Returns the server capabilities after initialization.

pub fn protocol_version(&self) -> Option<&str>

Returns the protocol version after initialization.

pub fn list_tools(&mut self) -> McpResult<Vec<Tool>>

Lists available tools.

Errors

Returns an error if the request fails.

pub fn call_tool( &mut self, name: &str, arguments: Value, ) -> McpResult<Vec<Content>>

Calls a tool with the given arguments.

Errors

Returns an error if the tool call fails.

pub fn list_resources(&mut self) -> McpResult<Vec<Resource>>

Lists available resources.

Errors

Returns an error if the request fails.

pub fn list_resource_templates(&mut self) -> McpResult<Vec<ResourceTemplate>>

Lists available resource templates.

Errors

Returns an error if the request fails.

pub fn read_resource(&mut self, uri: &str) -> McpResult<Vec<ResourceContent>>

Reads a resource by URI.

Errors

Returns an error if the resource cannot be read.

pub fn list_prompts(&mut self) -> McpResult<Vec<Prompt>>

Lists available prompts.

Errors

Returns an error if the request fails.

pub fn get_prompt( &mut self, name: &str, arguments: HashMap<String, String>, ) -> McpResult<Vec<PromptMessage>>

Gets a prompt with the given arguments.

Errors

Returns an error if the prompt cannot be retrieved.

pub fn send_raw_request( &mut self, method: &str, params: Value, ) -> McpResult<Value>

Sends a raw JSON-RPC request and returns the raw response.

Useful for testing custom or non-standard methods.

Errors

Returns an error if the request fails.

pub fn close(self)

Closes the client connection.

pub fn transport(&self) -> &MemoryTransport

Returns a reference to the transport for advanced testing.

pub fn transport_mut(&mut self) -> &mut MemoryTransport

Returns a mutable reference to the transport for advanced testing.

Trait Implementations

impl Debug for TestClient

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.