refactor: improve MCP client timeout handling and reactive testing

- Add configurable initialization timeout separate from request timeout
- Rename ServletSse* test classes to HttpSse* for better naming consistency
- Replace direct .block() calls with StepVerifier for better reactive testing
- Change ping() method to return Mono instead of Mono
- Improve error handling and reactive programming patterns throughout tests
- Chain reactive operations for cleaner test flow

Signed-off-by: Christian Tzolov <christian.tzolov@broadcom.com>

mcp/src/main/java/io/modelcontextprotocol/client/McpAsyncClient.java

@@ -88,7 +88,6 @@ public class McpAsyncClient {
 
 	/**
 	 * The max timeout to await for the client-server connection to be initialized.
-	 * Usually x2 the request timeout. // TODO should we make it configurable?
 	 */
 	private final Duration initializationTimeout;
 
@@ -151,18 +150,21 @@ public class McpAsyncClient {
 	 * timeout.
 	 * @param transport the transport to use.
 	 * @param requestTimeout the session request-response timeout.
+	 * @param initializationTimeout the max timeout to await for the client-server
 	 * @param features the MCP Client supported features.
 	 */
-	McpAsyncClient(ClientMcpTransport transport, Duration requestTimeout, McpClientFeatures.Async features) {
+	McpAsyncClient(ClientMcpTransport transport, Duration requestTimeout, Duration initializationTimeout,
+			McpClientFeatures.Async features) {
 
 		Assert.notNull(transport, "Transport must not be null");
 		Assert.notNull(requestTimeout, "Request timeout must not be null");
+		Assert.notNull(initializationTimeout, "Initialization timeout must not be null");
 
 		this.clientInfo = features.clientInfo();
 		this.clientCapabilities = features.clientCapabilities();
 		this.transport = transport;
 		this.roots = new ConcurrentHashMap<>(features.roots());
-		this.initializationTimeout = requestTimeout.multipliedBy(2);
+		this.initializationTimeout = initializationTimeout;
 
 		// Request Handlers
 		Map<String, RequestHandler<?>> requestHandlers = new HashMap<>();
@@ -367,12 +369,13 @@ public class McpAsyncClient {
 
 	/**
 	 * Sends a ping request to the server.
-	 * @return A Mono that completes with the server's ping response
+	 * @return A Mono that completes when the server responds to the ping
 	 */
-	public Mono<Object> ping() {
+	public Mono<Void> ping() {
 		return this.withInitializationCheck("pinging the server", initializedResult -> this.mcpSession
 			.sendRequest(McpSchema.METHOD_PING, null, new TypeReference<Object>() {
-			}));
+			})
+			.then());
 	}
 
 	// --------------------------
@@ -771,7 +774,9 @@ public class McpAsyncClient {
 	 * @see McpSchema.LoggingLevel
 	 */
 	public Mono<Void> setLoggingLevel(LoggingLevel loggingLevel) {
-		Assert.notNull(loggingLevel, "Logging level must not be null");
+		if (loggingLevel == null) {
+			return Mono.error(new McpError("Logging level must not be null"));
+		}
 
 		return this.withInitializationCheck("setting logging level", initializedResult -> {
 			String levelName = this.transport.unmarshalFrom(loggingLevel, new TypeReference<String>() {

mcp/src/main/java/io/modelcontextprotocol/client/McpClient.java

@@ -157,6 +157,8 @@ public interface McpClient {
 
 		private Duration requestTimeout = Duration.ofSeconds(20); // Default timeout
 
+		private Duration initializationTimeout = Duration.ofSeconds(20);
+
 		private ClientCapabilities capabilities;
 
 		private Implementation clientInfo = new Implementation("Java SDK MCP Client", "1.0.0");
@@ -193,6 +195,18 @@ public interface McpClient {
 			return this;
 		}
 
+		/**
+		 * @param initializationTimeout The duration to wait for the initializaiton
+		 * lifecycle step to complete.
+		 * @return This builder instance for method chaining
+		 * @throws IllegalArgumentException if initializationTimeout is null
+		 */
+		public SyncSpec initializationTimeout(Duration initializationTimeout) {
+			Assert.notNull(initializationTimeout, "Initialization timeout must not be null");
+			this.initializationTimeout = initializationTimeout;
+			return this;
+		}
+
 		/**
 		 * Sets the client capabilities that will be advertised to the server during
 		 * connection initialization. Capabilities define what features the client
@@ -354,7 +368,8 @@ public interface McpClient {
 
 			McpClientFeatures.Async asyncFeatures = McpClientFeatures.Async.fromSync(syncFeatures);
 
-			return new McpSyncClient(new McpAsyncClient(transport, this.requestTimeout, asyncFeatures));
+			return new McpSyncClient(
+					new McpAsyncClient(transport, this.requestTimeout, this.initializationTimeout, asyncFeatures));
 		}
 
 	}
@@ -381,6 +396,8 @@ public interface McpClient {
 
 		private Duration requestTimeout = Duration.ofSeconds(20); // Default timeout
 
+		private Duration initializationTimeout = Duration.ofSeconds(20);
+
 		private ClientCapabilities capabilities;
 
 		private Implementation clientInfo = new Implementation("Spring AI MCP Client", "0.3.1");
@@ -417,6 +434,18 @@ public interface McpClient {
 			return this;
 		}
 
+		/**
+		 * @param initializationTimeout The duration to wait for the initializaiton
+		 * lifecycle step to complete.
+		 * @return This builder instance for method chaining
+		 * @throws IllegalArgumentException if initializationTimeout is null
+		 */
+		public AsyncSpec initializationTimeout(Duration initializationTimeout) {
+			Assert.notNull(initializationTimeout, "Initialization timeout must not be null");
+			this.initializationTimeout = initializationTimeout;
+			return this;
+		}
+
 		/**
 		 * Sets the client capabilities that will be advertised to the server during
 		 * connection initialization. Capabilities define what features the client
@@ -574,7 +603,7 @@ public interface McpClient {
 		 * @return a new instance of {@link McpAsyncClient}.
 		 */
 		public McpAsyncClient build() {
-			return new McpAsyncClient(this.transport, this.requestTimeout,
+			return new McpAsyncClient(this.transport, this.requestTimeout, this.initializationTimeout,
 					new McpClientFeatures.Async(this.clientInfo, this.capabilities, this.roots,
 							this.toolsChangeConsumers, this.resourcesChangeConsumers, this.promptsChangeConsumers,
 							this.loggingConsumers, this.samplingHandler));

mcp/src/main/java/io/modelcontextprotocol/client/McpSyncClient.java

@@ -179,11 +179,10 @@ public class McpSyncClient implements AutoCloseable {
 	}
 
 	/**
-	 * Send a synchronous ping request.
-	 * @return
+	 * Send a synchronous ping request to the server.
 	 */
-	public Object ping() {
-		return this.delegate.ping().block();
+	public void ping() {
+		this.delegate.ping().block();
 	}
 
 	// --------------------------