Don't unsubscribe on auth change

PubNub/Core/PubNub+Core.m

@@ -302,12 +302,8 @@ - (void)copyWithConfiguration:(PNConfiguration *)configuration
         [self cancelSubscribeOperations];
 
         BOOL uuidChanged = ![configuration.userID isEqualToString:self.configuration.userID];
-        BOOL authKeyChanged = ((self.configuration.authKey && !configuration.authKey) ||
-                               (!self.configuration.authKey && configuration.authKey) ||
-                               (configuration.authKey && self.configuration.authKey &&
-                                ![configuration.authKey isEqualToString:self.configuration.authKey]));
-
-        if (uuidChanged || authKeyChanged) {
+
+        if (uuidChanged) {
             [self unsubscribeFromChannels:self.subscriberManager.channels 
                                    groups:self.subscriberManager.channelGroups
                              withPresence:YES

Tests/Tests/Unit/Core/Subscribe/PNCopyWithConfigurationSubscribeTest.m

@@ -578,6 +578,102 @@ - (void)testContinuationUsesLongPollWhenStateIsConnected {
 }
 
 
+#pragma mark - Tests :: copyWithConfiguration unsubscribe behavior
+
+/// Verify that `copyWithConfiguration:completion:` does **not** trigger an unsubscribe when only `authKey` changes.
+///
+/// When a token expires and is refreshed, the client should seamlessly continue its subscription on the new instance
+/// without sending a leave request with the old (possibly expired) credentials. The new client inherits subscriber state
+/// and resubscribes with the fresh auth key automatically.
+- (void)testCopyWithConfigurationDoesNotUnsubscribeWhenOnlyAuthKeyChanges {
+    [self.client.subscriberManager addChannels:@[@"test-channel"]];
+    self.client.subscriberManager.currentState = PNTestConnectedSubscriberState;
+
+    id clientMock = [self mockForObject:self.client];
+
+    OCMReject([clientMock unsubscribeFromChannels:[OCMArg any]
+                                           groups:[OCMArg any]
+                                     withPresence:YES
+                                  queryParameters:[OCMArg any]
+                                       completion:[OCMArg any]]);
+
+    PNConfiguration *newConfig = [self.client.configuration copy];
+    newConfig.authKey = @"new-auth-token";
+
+    XCTestExpectation *completionExpectation = [self expectationWithDescription:@"copyWithConfiguration: should complete"];
+
+    // Set up transport that will succeed for the new client's subscribe.
+    PNURLSessionTransport *transport = [PNURLSessionTransport new];
+    PNTransportConfiguration *transportConfig = [PNTransportConfiguration new];
+    transportConfig.maximumConnections = 1;
+    [transport setupWithConfiguration:transportConfig];
+
+    NSURLSessionConfiguration *sessionConfig = [NSURLSessionConfiguration ephemeralSessionConfiguration];
+    sessionConfig.protocolClasses = @[[PNSlowSubscribeProtocol class]];
+    NSOperationQueue *opQueue = [NSOperationQueue new];
+    opQueue.maxConcurrentOperationCount = 1;
+    NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfig delegate:nil delegateQueue:opQueue];
+    [transport setValue:session forKey:@"session"];
+
+    [self.client copyWithConfiguration:newConfig completion:^(PubNub *client) {
+        client.subscriptionNetwork = transport;
+        [completionExpectation fulfill];
+    }];
+
+    // Complete the new client's subscribe request so the completion fires.
+    [self waitForCondition:^BOOL {
+        return [PNSlowSubscribeProtocol pendingCount] > 0;
+    } withTimeout:3.0 description:@"New client's subscribe request should be in-flight"];
+    [PNSlowSubscribeProtocol completeAllPendingWithSuccess];
+
+    [self waitForExpectationsWithTimeout:1.0 handler:nil];
+
+    OCMVerifyAll(clientMock);
+}
+
+/// Verify that `copyWithConfiguration:completion:` **does** trigger an unsubscribe when `userID` changes.
+///
+/// A user identity change means the server-side presence state (join/leave) is tied to the old identity.
+/// The old client must send a leave so presence accurately reflects that the old user departed, before the new client
+/// subscribes under the new identity.
+- (void)testCopyWithConfigurationUnsubscribesWhenUserIDChanges {
+    [self.client.subscriberManager addChannels:@[@"test-channel"]];
+    self.client.subscriberManager.currentState = PNTestConnectedSubscriberState;
+
+    __block BOOL unsubscribeCalled = NO;
+    id clientMock = [self mockForObject:self.client];
+
+    OCMStub([clientMock unsubscribeFromChannels:[OCMArg any]
+                                         groups:[OCMArg any]
+                                   withPresence:YES
+                                queryParameters:[OCMArg any]
+                                     completion:([OCMArg invokeBlockWithArgs:[NSNull null], nil])])
+        .andDo(^(__unused NSInvocation *invocation) {
+            unsubscribeCalled = YES;
+        });
+
+    PNConfiguration *newConfig = [self.client.configuration copy];
+    newConfig.userID = @"different-user-id";
+
+    XCTestExpectation *completionExpectation = [self expectationWithDescription:@"copyWithConfiguration: should complete"];
+
+    [self.client copyWithConfiguration:newConfig completion:^(PubNub *client) {
+        [completionExpectation fulfill];
+    }];
+
+    // Complete the new client's subscribe request.
+    [self waitForCondition:^BOOL {
+        return [PNSlowSubscribeProtocol pendingCount] > 0;
+    } withTimeout:3.0 description:@"New client's subscribe request should be in-flight"];
+    [PNSlowSubscribeProtocol completeAllPendingWithSuccess];
+
+    [self waitForExpectationsWithTimeout:1.0 handler:nil];
+
+    XCTAssertTrue(unsubscribeCalled,
+                  @"copyWithConfiguration: should unsubscribe from old identity when userID changes");
+}
+
+
 #pragma mark - Helpers