fix: Update AbstractA2AServerTestCase to add a test for sending a new streaming messgage using the Client instead of HttpClient

Author: fjuma

tests/server-common/src/test/java/io/a2a/server/apps/common/AbstractA2AServerTest.java

@@ -959,14 +959,64 @@ public void testStreamingMethodWithAcceptHeader() throws Exception {
     }
 
     @Test
-    public void testSendMessageStreamNewMessageSuccess() throws Exception {
+    public void testStreamingMethodWithoutAcceptHeader() throws Exception {
         // skip this test for non-JSONRPC transports
         assumeTrue(TransportProtocol.JSONRPC.asString().equals(getTransportProtocol()),
                 "JSONRPC-specific test");
-        
+
         testSendStreamingMessage(null);
     }
 
+    @Test
+    public void testSendMessageStreamNewMessageSuccess() throws Exception {
+        try {
+            Message message = new Message.Builder(MESSAGE)
+                    .taskId(MINIMAL_TASK.getId())
+                    .contextId(MINIMAL_TASK.getContextId())
+                    .build();
+
+            CountDownLatch latch = new CountDownLatch(1);
+            AtomicReference<Message> receivedMessage = new AtomicReference<>();
+            AtomicBoolean wasUnexpectedEvent = new AtomicBoolean(false);
+            AtomicReference<Throwable> errorRef = new AtomicReference<>();
+
+            BiConsumer<ClientEvent, AgentCard> consumer = (event, agentCard) -> {
+                if (event instanceof MessageEvent messageEvent) {
+                    if (latch.getCount() > 0) {
+                        receivedMessage.set(messageEvent.getMessage());
+                        latch.countDown();
+                    } else {
+                        wasUnexpectedEvent.set(true);
+                    }
+                } else {
+                    wasUnexpectedEvent.set(true);
+                }
+            };
+
+            Consumer<Throwable> errorHandler = error -> {
+                errorRef.set(error);
+                latch.countDown();
+            };
+
+            // testing the streaming send message
+            getClient().sendMessage(message, List.of(consumer), errorHandler);
+
+            assertTrue(latch.await(10, TimeUnit.SECONDS));
+            assertFalse(wasUnexpectedEvent.get());
+            assertNull(errorRef.get());
+
+            Message messageResponse = receivedMessage.get();
+            assertNotNull(messageResponse);
+            assertEquals(MESSAGE.getMessageId(), messageResponse.getMessageId());
+            assertEquals(MESSAGE.getRole(), messageResponse.getRole());
+            Part<?> part = messageResponse.getParts().get(0);
+            assertEquals(Part.Kind.TEXT, part.getKind());
+            assertEquals("test message", ((TextPart) part).getText());
+        } catch (A2AClientException e) {
+            fail("Unexpected exception during sendMessage: " + e.getMessage(), e);
+        }
+    }
+
     private void testSendStreamingMessage(String mediaType) throws Exception {
         Message message = new Message.Builder(MESSAGE)
                 .taskId(MINIMAL_TASK.getId())