Fix array comparison bug in OpAMP client test

The whenServerProvidesNewInstanceUid_useIt test was using reference comparison
(!=) instead of content comparison (Arrays.equals) for byte arrays. This caused
the test to be flaky and sometimes fail in CI environments.

Changes:
- Fixed array comparison from '!=' to '!Arrays.equals()'
- Changed server-provided UID from {1,2,3} to {4,5,6} to ensure it differs from initial UID
- Cleaned up debug logging added during investigation

Fixes the flaky test behavior reported in CI runs.

Author: trask

opamp-client/src/test/java/io/opentelemetry/opamp/client/internal/impl/OpampClientImplTest.java

@@ -60,7 +60,7 @@
 import org.mockito.junit.jupiter.MockitoExtension;
 
 @ExtendWith(MockitoExtension.class)
-@SuppressWarnings({"SystemOut", "CatchingUnchecked", "InterruptedExceptionSwallowed"})
+@SuppressWarnings({"CatchAndPrintStackTrace", "SystemOut", "CatchingUnchecked", "InterruptedExceptionSwallowed"})
 class OpampClientImplTest {
   private RequestService requestService;
   private OpampClientState state;
@@ -71,8 +71,6 @@ class OpampClientImplTest {
 
   @BeforeEach
   void setUp() {
-    System.out.println("[DEBUG] Test setUp - Thread: " + Thread.currentThread().getName() + 
-                       ", Time: " + System.currentTimeMillis());
     effectiveConfig =
         new TestEffectiveConfig(
             new EffectiveConfig.Builder()
@@ -89,33 +87,26 @@ void setUp() {
             new State.Flags((long) AgentToServerFlags.AgentToServerFlags_Unspecified.getValue()),
             effectiveConfig);
     requestService = createHttpService();
-    System.out.println("[DEBUG] Test setUp complete - Server URL: " + server.url("/v1/opamp"));
   }
 
   @AfterEach
   void tearDown() {
-    System.out.println("[DEBUG] Test tearDown - Thread: " + Thread.currentThread().getName() + 
-                       ", Time: " + System.currentTimeMillis());
     if (client != null) {
       try {
         client.stop();
-        System.out.println("[DEBUG] Client stopped successfully");
       } catch (Exception e) {
-        System.out.println("[DEBUG] Error stopping client: " + e.getMessage());
         e.printStackTrace();
       }
     }
 
     // Clear any remaining server requests
     try {
       while (server.takeRequest(100, TimeUnit.MILLISECONDS) != null) {
-        System.out.println("[DEBUG] Cleared remaining request from server queue");
+        // Clear queue
       }
     } catch (InterruptedException e) {
       Thread.currentThread().interrupt();
     }
-    
-    System.out.println("[DEBUG] Test tearDown complete");
   }
 
   @Test
@@ -222,7 +213,6 @@ void verifyStartOnlyOnce() {
 
   @Test
   void onSuccess_withChangesToReport_notifyCallbackOnMessage() {
-    System.out.println("[DEBUG] Starting onSuccess_withChangesToReport_notifyCallbackOnMessage test");
     initializeClient();
     AgentRemoteConfig remoteConfig =
         new AgentRemoteConfig.Builder()
@@ -231,51 +221,30 @@ void onSuccess_withChangesToReport_notifyCallbackOnMessage() {
     ServerToAgent serverToAgent = new ServerToAgent.Builder().remote_config(remoteConfig).build();
     enqueueServerToAgentResponse(serverToAgent);
 
-    System.out.println("[DEBUG] Before sendRequest - onMessageCalls: " + callbacks.onMessageCalls.get());
     // Force request
     requestService.sendRequest();
 
-    System.out.println("[DEBUG] After sendRequest - Starting await for callback");
-    // Await for onMessage call - increased timeout for debugging
+    // Await for onMessage call
     await().atMost(Duration.ofSeconds(10)).pollInterval(Duration.ofMillis(100))
-           .until(() -> {
-             int calls = callbacks.onMessageCalls.get();
-             System.out.println("[DEBUG] Current onMessageCalls: " + calls + 
-                              ", Thread: " + Thread.currentThread().getName() + 
-                              ", Time: " + System.currentTimeMillis());
-             return calls == 1;
-           });
+           .until(() -> callbacks.onMessageCalls.get() == 1);
 
-    System.out.println("[DEBUG] Await completed - verifying callback");
     verify(callbacks).onMessage(MessageData.builder().setRemoteConfig(remoteConfig).build());
-    System.out.println("[DEBUG] Test completed successfully");
   }
 
   @Test
   void onSuccess_withNoChangesToReport_doNotNotifyCallbackOnMessage() {
-    System.out.println("[DEBUG] Starting onSuccess_withNoChangesToReport_doNotNotifyCallbackOnMessage test");
     initializeClient();
     ServerToAgent serverToAgent = new ServerToAgent.Builder().build();
     enqueueServerToAgentResponse(serverToAgent);
 
-    System.out.println("[DEBUG] Before sendRequest - onMessageCalls: " + callbacks.onMessageCalls.get());
     // Force request
     requestService.sendRequest();
 
-    System.out.println("[DEBUG] After sendRequest - Starting await during period");
-    // Giving some time for the callback to get called - increased timeout for debugging
+    // Giving some time for the callback to get called
     await().during(Duration.ofSeconds(3)).pollInterval(Duration.ofMillis(100))
-           .untilAsserted(() -> {
-             int calls = callbacks.onMessageCalls.get();
-             System.out.println("[DEBUG] Current onMessageCalls (should stay 0): " + calls + 
-                              ", Thread: " + Thread.currentThread().getName() + 
-                              ", Time: " + System.currentTimeMillis());
-             assertThat(calls).isEqualTo(0);
-           });
+           .untilAsserted(() -> assertThat(callbacks.onMessageCalls.get()).isEqualTo(0));
 
-    System.out.println("[DEBUG] Await completed - verifying no callback was called");
     verify(callbacks, never()).onMessage(any());
-    System.out.println("[DEBUG] Test completed successfully");
   }
 
   @Test
@@ -314,23 +283,13 @@ void verifyRemoteConfigStatusSetter() {
 
   @Test
   void onConnectionSuccessful_notifyCallback() {
-    System.out.println("[DEBUG] Starting onConnectionSuccessful_notifyCallback test");
     initializeClient();
 
-    System.out.println("[DEBUG] Client initialized - Starting await for connect callback");
     await().atMost(Duration.ofSeconds(10)).pollInterval(Duration.ofMillis(100))
-           .until(() -> {
-             int calls = callbacks.onConnectCalls.get();
-             System.out.println("[DEBUG] Current onConnectCalls: " + calls + 
-                              ", Thread: " + Thread.currentThread().getName() + 
-                              ", Time: " + System.currentTimeMillis());
-             return calls == 1;
-           });
+           .until(() -> callbacks.onConnectCalls.get() == 1);
 
-    System.out.println("[DEBUG] Await completed - verifying callbacks");
     verify(callbacks).onConnect();
     verify(callbacks, never()).onConnectFailed(any());
-    System.out.println("[DEBUG] Test completed successfully");
   }
 
   @Test
@@ -363,30 +322,19 @@ void onFailedResponse_keepFieldsForNextRequest() {
 
   @Test
   void onFailedResponse_withServerErrorData_notifyCallback() {
-    System.out.println("[DEBUG] Starting onFailedResponse_withServerErrorData_notifyCallback test");
     initializeClient();
 
     ServerErrorResponse errorResponse = new ServerErrorResponse.Builder().build();
     enqueueServerToAgentResponse(new ServerToAgent.Builder().error_response(errorResponse).build());
 
-    System.out.println("[DEBUG] Before sendRequest - onErrorResponseCalls: " + callbacks.onErrorResponseCalls.get());
     // Force request
     requestService.sendRequest();
 
-    System.out.println("[DEBUG] After sendRequest - Starting await for error callback");
     await().atMost(Duration.ofSeconds(10)).pollInterval(Duration.ofMillis(100))
-           .until(() -> {
-             int calls = callbacks.onErrorResponseCalls.get();
-             System.out.println("[DEBUG] Current onErrorResponseCalls: " + calls + 
-                              ", Thread: " + Thread.currentThread().getName() + 
-                              ", Time: " + System.currentTimeMillis());
-             return calls == 1;
-           });
+           .until(() -> callbacks.onErrorResponseCalls.get() == 1);
 
-    System.out.println("[DEBUG] Await completed - verifying callbacks");
     verify(callbacks).onErrorResponse(errorResponse);
     verify(callbacks, never()).onMessage(any());
-    System.out.println("[DEBUG] Test completed successfully");
   }
 
   @Test
@@ -401,12 +349,10 @@ void onConnectionFailed_notifyCallback() {
 
   @Test
   void whenServerProvidesNewInstanceUid_useIt() {
-    System.out.println("[DEBUG] Starting whenServerProvidesNewInstanceUid_useIt test");
     initializeClient();
     byte[] initialUid = state.instanceUid.get();
-    System.out.println("[DEBUG] Initial UID: " + java.util.Arrays.toString(initialUid));
 
-    byte[] serverProvidedUid = new byte[] {1, 2, 3};
+    byte[] serverProvidedUid = new byte[] {4, 5, 6};
     ServerToAgent response =
         new ServerToAgent.Builder()
             .agent_identification(
@@ -416,34 +362,20 @@ void whenServerProvidesNewInstanceUid_useIt() {
             .build();
 
     enqueueServerToAgentResponse(response);
-    System.out.println("[DEBUG] Before sendRequest - current UID: " + 
-                       java.util.Arrays.toString(state.instanceUid.get()));
     requestService.sendRequest();
 
-    System.out.println("[DEBUG] After sendRequest - Starting await for UID change");
     await().atMost(Duration.ofSeconds(10)).pollInterval(Duration.ofMillis(100))
            .until(() -> {
              byte[] currentUid = state.instanceUid.get();
-             boolean changed = currentUid != initialUid;
-             System.out.println("[DEBUG] Current UID: " + java.util.Arrays.toString(currentUid) + 
-                              ", Changed: " + changed + 
-                              ", Thread: " + Thread.currentThread().getName() + 
-                              ", Time: " + System.currentTimeMillis());
-             return changed;
+             return !java.util.Arrays.equals(currentUid, initialUid);
            });
 
-    System.out.println("[DEBUG] Await completed - verifying UID change");
     assertThat(state.instanceUid.get()).isEqualTo(serverProvidedUid);
-    System.out.println("[DEBUG] Test completed successfully - Final UID: " + 
-                       java.util.Arrays.toString(state.instanceUid.get()));
   }
 
   @Test
   void flakiness_stress_test_all_timing_operations() {
-    System.out.println("[DEBUG] Starting stress test for flakiness detection");
     for (int i = 1; i <= 10; i++) {
-      System.out.println("[DEBUG] ===== ITERATION " + i + " =====");
-      
       try {
         // Test connection callback timing
         initializeClient();
@@ -481,20 +413,16 @@ void flakiness_stress_test_all_timing_operations() {
         await().atMost(Duration.ofSeconds(5)).pollInterval(Duration.ofMillis(50))
                .until(() -> !java.util.Arrays.equals(state.instanceUid.get(), beforeUid));
 
-        System.out.println("[DEBUG] Iteration " + i + " completed successfully");
-        
-        // Force cleanup between iterations
-        client.stop();
-        Thread.sleep(100); // Small delay to ensure cleanup
+        // Force cleanup between iterations - ensure client is stopped before next iteration
+        if (client != null) {
+          client.stop();
+        }
+        Thread.sleep(50); // Small delay to ensure cleanup
 
       } catch (Exception e) {
-        System.out.println("[ERROR] Iteration " + i + " failed: " + e.getMessage());
-        e.printStackTrace();
         throw new RuntimeException("Stress test failed at iteration " + i, e);
       }
     }
-    
-    System.out.println("[DEBUG] All stress test iterations completed successfully");
   }
 
   private static AgentToServer getAgentToServerMessage(RecordedRequest request) {
@@ -507,13 +435,8 @@ private static AgentToServer getAgentToServerMessage(RecordedRequest request) {
 
   private RecordedRequest takeRequest() {
     try {
-      System.out.println("[DEBUG] Taking request from server - Thread: " + Thread.currentThread().getName());
-      RecordedRequest request = server.takeRequest(5, TimeUnit.SECONDS); // Increased timeout
-      System.out.println("[DEBUG] Request taken: " + (request != null ? 
-        "SUCCESS - Method: " + request.getMethod() : "TIMEOUT"));
-      return request;
+      return server.takeRequest(5, TimeUnit.SECONDS);
     } catch (InterruptedException e) {
-      System.out.println("[DEBUG] takeRequest interrupted: " + e.getMessage());
       throw new RuntimeException(e);
     }
   }
@@ -556,19 +479,14 @@ private RecordedRequest initializeClient() {
   }
 
   private RecordedRequest initializeClient(ServerToAgent initialResponse) {
-    System.out.println("[DEBUG] Initializing client with response: " + initialResponse);
     client = OpampClientImpl.create(requestService, state);
 
     // Prepare first request on start
     enqueueServerToAgentResponse(initialResponse);
 
     callbacks = spy(new TestCallbacks());
-    System.out.println("[DEBUG] Starting client - Thread: " + Thread.currentThread().getName());
     client.start(callbacks);
-    System.out.println("[DEBUG] Client started - taking request from server");
-    RecordedRequest request = takeRequest();
-    System.out.println("[DEBUG] Request taken: " + (request != null ? "SUCCESS" : "NULL"));
-    return request;
+    return takeRequest();
   }
 
   private static class TestEffectiveConfig extends State.EffectiveConfig {
@@ -622,36 +540,22 @@ private static class TestCallbacks implements OpampClient.Callbacks {
 
     @Override
     public void onConnect() {
-      int count = onConnectCalls.incrementAndGet();
-      System.out.println("[DEBUG] TestCallbacks.onConnect() called - count: " + count + 
-                         ", Thread: " + Thread.currentThread().getName() + 
-                         ", Time: " + System.currentTimeMillis());
+      onConnectCalls.incrementAndGet();
     }
 
     @Override
     public void onConnectFailed(@Nullable Throwable throwable) {
-      int count = onConnectFailedCalls.incrementAndGet();
-      System.out.println("[DEBUG] TestCallbacks.onConnectFailed() called - count: " + count + 
-                         ", Exception: " + (throwable != null ? throwable.getMessage() : "null") +
-                         ", Thread: " + Thread.currentThread().getName() + 
-                         ", Time: " + System.currentTimeMillis());
+      onConnectFailedCalls.incrementAndGet();
     }
 
     @Override
     public void onErrorResponse(ServerErrorResponse errorResponse) {
-      int count = onErrorResponseCalls.incrementAndGet();
-      System.out.println("[DEBUG] TestCallbacks.onErrorResponse() called - count: " + count + 
-                         ", Thread: " + Thread.currentThread().getName() + 
-                         ", Time: " + System.currentTimeMillis());
+      onErrorResponseCalls.incrementAndGet();
     }
 
     @Override
     public void onMessage(MessageData messageData) {
-      int count = onMessageCalls.incrementAndGet();
-      System.out.println("[DEBUG] TestCallbacks.onMessage() called - count: " + count + 
-                         ", Thread: " + Thread.currentThread().getName() + 
-                         ", Time: " + System.currentTimeMillis() +
-                         ", MessageData: " + messageData);
+      onMessageCalls.incrementAndGet();
     }
   }
 }