Fix flaky test running blocking code in event loop

Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>

Author: chemicL

mcp-spring/mcp-spring-webflux/src/test/java/io/modelcontextprotocol/WebFluxSseIntegrationTests.java

@@ -35,10 +35,8 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
-import reactor.core.publisher.Mono;
 import reactor.netty.DisposableServer;
 import reactor.netty.http.server.HttpServer;
-import reactor.test.StepVerifier;
 
 import org.springframework.http.server.reactive.HttpHandler;
 import org.springframework.http.server.reactive.ReactorHttpHandlerAdapter;
@@ -47,6 +45,7 @@
 import org.springframework.web.reactive.function.server.RouterFunctions;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertWith;
 import static org.awaitility.Awaitility.await;
 import static org.mockito.Mockito.mock;
 
@@ -106,12 +105,9 @@ void testCreateMessageWithoutSamplingCapabilities(String clientType) {
 		var clientBuilder = clientBuilders.get(clientType);
 
 		McpServerFeatures.AsyncToolSpecification tool = new McpServerFeatures.AsyncToolSpecification(
-				new McpSchema.Tool("tool1", "tool1 description", emptyJsonSchema), (exchange, request) -> {
-
-					exchange.createMessage(mock(McpSchema.CreateMessageRequest.class)).block();
-
-					return Mono.just(mock(CallToolResult.class));
-				});
+				new McpSchema.Tool("tool1", "tool1 description", emptyJsonSchema),
+				(exchange, request) -> exchange.createMessage(mock(CreateMessageRequest.class))
+					.thenReturn(mock(CallToolResult.class)));
 
 		var server = McpServer.async(mcpServerTransportProvider).serverInfo("test-server", "1.0.0").tools(tool).build();
 
@@ -148,6 +144,8 @@ void testCreateMessageSuccess(String clientType) throws InterruptedException {
 		CallToolResult callResponse = new McpSchema.CallToolResult(List.of(new McpSchema.TextContent("CALL RESPONSE")),
 				null);
 
+		AtomicReference<CreateMessageResult> samplingResult = new AtomicReference<>();
+
 		McpServerFeatures.AsyncToolSpecification tool = new McpServerFeatures.AsyncToolSpecification(
 				new McpSchema.Tool("tool1", "tool1 description", emptyJsonSchema), (exchange, request) -> {
 
@@ -162,16 +160,9 @@ void testCreateMessageSuccess(String clientType) throws InterruptedException {
 							.build())
 						.build();
 
-					StepVerifier.create(exchange.createMessage(craeteMessageRequest)).consumeNextWith(result -> {
-						assertThat(result).isNotNull();
-						assertThat(result.role()).isEqualTo(Role.USER);
-						assertThat(result.content()).isInstanceOf(McpSchema.TextContent.class);
-						assertThat(((McpSchema.TextContent) result.content()).text()).isEqualTo("Test message");
-						assertThat(result.model()).isEqualTo("MockModelName");
-						assertThat(result.stopReason()).isEqualTo(CreateMessageResult.StopReason.STOP_SEQUENCE);
-					}).verifyComplete();
-
-					return Mono.just(callResponse);
+					return exchange.createMessage(craeteMessageRequest)
+						.doOnNext(samplingResult::set)
+						.thenReturn(callResponse);
 				});
 
 		var mcpServer = McpServer.async(mcpServerTransportProvider)
@@ -191,8 +182,17 @@ void testCreateMessageSuccess(String clientType) throws InterruptedException {
 
 			assertThat(response).isNotNull();
 			assertThat(response).isEqualTo(callResponse);
+
+			assertWith(samplingResult.get(), result -> {
+				assertThat(result).isNotNull();
+				assertThat(result.role()).isEqualTo(Role.USER);
+				assertThat(result.content()).isInstanceOf(McpSchema.TextContent.class);
+				assertThat(((McpSchema.TextContent) result.content()).text()).isEqualTo("Test message");
+				assertThat(result.model()).isEqualTo("MockModelName");
+				assertThat(result.stopReason()).isEqualTo(CreateMessageResult.StopReason.STOP_SEQUENCE);
+			});
 		}
-		mcpServer.close();
+		mcpServer.closeGracefully().block();
 	}
 
 	// ---------------------------------------