feat: Handle MCP server notification messages (#2613)

Co-authored-by: Michael Neale <michael.neale@gmail.com>

crates/mcp-client/examples/integration_test.rs

@@ -0,0 +1,122 @@
+use anyhow::Result;
+use futures::lock::Mutex;
+use mcp_client::client::{ClientCapabilities, ClientInfo, McpClient, McpClientTrait};
+use mcp_client::transport::{SseTransport, Transport};
+use mcp_client::StdioTransport;
+use std::collections::HashMap;
+use std::sync::Arc;
+use std::time::Duration;
+use tracing_subscriber::EnvFilter;
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    // Initialize logging
+    tracing_subscriber::fmt()
+        .with_env_filter(
+            EnvFilter::from_default_env()
+                .add_directive("mcp_client=debug".parse().unwrap())
+                .add_directive("eventsource_client=info".parse().unwrap()),
+        )
+        .init();
+
+    test_transport(sse_transport().await?).await?;
+    test_transport(stdio_transport().await?).await?;
+
+    Ok(())
+}
+
+async fn sse_transport() -> Result<SseTransport> {
+    let port = "60053";
+
+    tokio::process::Command::new("npx")
+        .env("PORT", port)
+        .arg("@modelcontextprotocol/server-everything")
+        .arg("sse")
+        .spawn()?;
+    tokio::time::sleep(Duration::from_secs(1)).await;
+
+    Ok(SseTransport::new(
+        format!("http://localhost:{}/sse", port),
+        HashMap::new(),
+    ))
+}
+
+async fn stdio_transport() -> Result<StdioTransport> {
+    Ok(StdioTransport::new(
+        "npx",
+        vec!["@modelcontextprotocol/server-everything"]
+            .into_iter()
+            .map(|s| s.to_string())
+            .collect(),
+        HashMap::new(),
+    ))
+}
+
+async fn test_transport<T>(transport: T) -> Result<()>
+where
+    T: Transport + Send + 'static,
+{
+    // Start transport
+    let handle = transport.start().await?;
+
+    // Create client
+    let mut client = McpClient::connect(handle, Duration::from_secs(10)).await?;
+    println!("Client created\n");
+
+    let mut receiver = client.subscribe().await;
+    let events = Arc::new(Mutex::new(Vec::new()));
+    let events_clone = events.clone();
+    tokio::spawn(async move {
+        while let Some(event) = receiver.recv().await {
+            println!("Received event: {event:?}");
+            events_clone.lock().await.push(event);
+        }
+    });
+
+    // Initialize
+    let server_info = client
+        .initialize(
+            ClientInfo {
+                name: "test-client".into(),
+                version: "1.0.0".into(),
+            },
+            ClientCapabilities::default(),
+        )
+        .await?;
+    println!("Connected to server: {server_info:?}\n");
+
+    // Sleep for 100ms to allow the server to start - surprisingly this is required!
+    tokio::time::sleep(Duration::from_millis(500)).await;
+
+    // List tools
+    let tools = client.list_tools(None).await?;
+    println!("Available tools: {tools:#?}\n");
+
+    // Call tool
+    let tool_result = client
+        .call_tool("echo", serde_json::json!({ "message": "honk" }))
+        .await?;
+    println!("Tool result: {tool_result:#?}\n");
+
+    let collected_eventes_before = events.lock().await.len();
+    let n_steps = 5;
+    let long_op = client
+        .call_tool(
+            "longRunningOperation",
+            serde_json::json!({ "duration": 3, "steps": n_steps }),
+        )
+        .await?;
+    println!("Long op result: {long_op:#?}\n");
+    let collected_events_after = events.lock().await.len();
+    assert_eq!(collected_events_after - collected_eventes_before, n_steps);
+
+    // List resources
+    let resources = client.list_resources(None).await?;
+    println!("Resources: {resources:#?}\n");
+
+    // Read resource
+    let resource = client.read_resource("test://static/resource/1").await?;
+    println!("Resource: {resource:#?}\n");
+
+    Ok(())
+}