Add support for notifying the delegate when device configuration changes

- Device configuration changes include updates in attributes parts list, server list,
  device type list, cluster revision or feature map in the descriptor cluster

- Add a test to verify the delegate is notified when device configuration changes

src/darwin/Framework/CHIP/MTRDevice.h

@@ -423,6 +423,16 @@ MTR_EXTERN NSString * const MTRDataVersionKey MTR_NEWLY_AVAILABLE;
  */
 - (void)deviceCachePrimed:(MTRDevice *)device MTR_NEWLY_AVAILABLE;
 
+/**
+ * Notifies delegate when the device configuration changes. Device configuration changes include updates in parts list, device list,
+ * server list, feature map or cluster revision attributes in the descriptor cluster.
+ *
+ * This is called when the MTRDevice object detects a change in the device configuration and reports that to the delegate.
+ *
+ * The intention is that after this is called, the client should re-enumerate the device topology.
+ */
+- (void)deviceConfigurationChanged:(MTRDevice *)device MTR_NEWLY_AVAILABLE;
+
 @end
 
 @interface MTRDevice (Deprecated)

src/darwin/Framework/CHIP/MTRDevice.mm

@@ -371,6 +371,11 @@ @implementation MTRDevice {
     // ReadClient).  Nil if we have had no such failures.
     NSDate * _Nullable _lastSubscriptionFailureTime;
     MTRDeviceConnectivityMonitor * _connectivityMonitor;
+
+    // This boolean keeps track of any device configuration changes received in an attribute report
+    // and when the report ends, we notify the delegate. Device configuration changes include parts
+    // list, server list, device list, cluster revision and feature map updates.
+    BOOL _deviceConfigurationChanged;
 }
 
 - (instancetype)initWithNodeID:(NSNumber *)nodeID controller:(MTRDeviceController *)controller
@@ -1063,6 +1068,19 @@ - (void)_handleReportEnd
         _clustersToPersist = nil;
     }
 
+    // After the handling of the report, if we detected a device configuration change, notify the delegate
+    // of the same.
+    if (_deviceConfigurationChanged)
+    {
+        id<MTRDeviceDelegate> delegate = _weakDelegate.strongObject;
+        if (delegate) {
+            dispatch_async(_delegateQueue, ^{
+                if ([delegate respondsToSelector:@selector(deviceConfigurationChanged:)])
+                    [delegate deviceConfigurationChanged:self];
+            });
+        }
+    }
+
 // For unit testing only
 #ifdef DEBUG
     id delegate = _weakDelegate.strongObject;
@@ -1090,10 +1108,44 @@ - (void)_reportAttributes:(NSArray<NSDictionary<NSString *, id> *> *)attributes
     }
 }
 
+// When we receive an attribute report, check if there are any changes in parts list, server list, device type list, cluster revision
+// or feature map attributes of the descriptor cluster. If yes, make a note that the device configuration changed.
+- (void) _noteDeviceConfigurationChanged:(NSArray<NSDictionary<NSString *, id> *> *)attributeReport
+{
+    for (NSDictionary<NSString *, id> * attribute in attributeReport) {
+        MTRAttributePath * attributePath = attribute[MTRAttributePathKey];
+
+        if (attributePath.cluster.unsignedLongValue != MTRClusterDescriptorID)
+        {
+            return;
+        }
+
+        switch (attributePath.attribute.unsignedLongValue)
+        {
+            case MTRClusterDescriptorAttributePartsListID:
+            case MTRClusterDescriptorAttributeServerListID:
+            case MTRClusterDescriptorAttributeDeviceTypeListID:
+            case MTRClusterDescriptorAttributeClusterRevisionID:
+            case MTRClusterDescriptorAttributeFeatureMapID:
+            {
+                // If changes are detected, note that the device configuration has changed.
+                NSDictionary * cachedAttributeDataValue = [self _cachedAttributeValueForPath:attributePath];
+                if (cachedAttributeDataValue != nil && ![self _attributeDataValue:attribute[MTRDataKey] isEqualToDataValue:cachedAttributeDataValue])
+                {
+                    _deviceConfigurationChanged = YES;
+                    break;
+                }
+            }
+        }
+    }
+}
+
 - (void)_handleAttributeReport:(NSArray<NSDictionary<NSString *, id> *> *)attributeReport
 {
     std::lock_guard lock(_lock);
 
+    [self _noteDeviceConfigurationChanged:attributeReport];
+
     // _getAttributesToReportWithReportedValues will log attribute paths reported
     [self _reportAttributes:[self _getAttributesToReportWithReportedValues:attributeReport]];
 }
@@ -1105,6 +1157,15 @@ - (void)unitTestInjectEventReport:(NSArray<NSDictionary<NSString *, id> *> *)eve
         [self _handleEventReport:eventReport];
     });
 }
+
+- (void)unitTestInjectAttributeReport:(NSArray<NSDictionary<NSString *, id> *> *)attributeReport
+{
+    dispatch_async(self.queue, ^{
+        [self _handleReportBegin];
+        [self _handleAttributeReport:attributeReport];
+        [self _handleReportEnd];
+    });
+}
 #endif
 
 - (void)_handleEventReport:(NSArray<NSDictionary<NSString *, id> *> *)eventReport

src/darwin/Framework/CHIPTests/MTRDeviceTests.m

@@ -2974,6 +2974,7 @@ - (void)test031_MTRDeviceAttributeCacheLocalTestStorage
     }
     NSUInteger storedAttributeCountDifferenceFromMTRDeviceReport = dataStoreAttributeCountAfterSecondSubscription - attributesReportedWithSecondSubscription;
     XCTAssertTrue(storedAttributeCountDifferenceFromMTRDeviceReport > 300);
+    [sController removeDevice:device];
 }
 
 - (void)test032_MTRPathClassesEncoding
@@ -3020,6 +3021,115 @@ - (void)test032_MTRPathClassesEncoding
     XCTAssertEqualObjects(originalCommandPath, decodedCommandPath);
 }
 
+#ifdef DEBUG
+- (void)test033_TestMTRDeviceDeviceConfigurationChanged
+{
+    // Ensure the test starts with clean slate.
+    [sController.controllerDataStore clearAllStoredClusterData];
+    NSDictionary * storedClusterDataAfterClear = [sController.controllerDataStore getStoredClusterDataForNodeID:@(kDeviceId)];
+    XCTAssertEqual(storedClusterDataAfterClear.count, 0);
+
+    __auto_type * device = [MTRDevice deviceWithNodeID:kDeviceId deviceController:sController];
+    dispatch_queue_t queue = dispatch_get_main_queue();
+
+    // Check if subscription is set up and initial reports are received.
+    XCTestExpectation * subscriptionExpectation = [self expectationWithDescription:@"Subscription has been set up"];
+    XCTestExpectation * gotInitialReportsExpectation = [self expectationWithDescription:@"Initial Attribute and Event reports have been received"];
+
+    __auto_type * delegate = [[MTRDeviceTestDelegate alloc] init];
+    delegate.onReachable = ^() {
+        [subscriptionExpectation fulfill];
+    };
+
+    delegate.onReportEnd = ^() {
+        [gotInitialReportsExpectation fulfill];
+    };
+
+    [device setDelegate:delegate queue:queue];
+
+    // Wait for subscription set up and intitial reports received.
+    [self waitForExpectations:@[ subscriptionExpectation, gotInitialReportsExpectation, ] timeout:60];
+
+    XCTestExpectation * gotAttributeReportExpectation = [self expectationWithDescription:@"Attribute report has been received"];
+    XCTestExpectation * gotAttributeReportEndExpectation = [self expectationWithDescription:@"Attribute report has ended"];
+    XCTestExpectation * deviceConfigurationChangedExpectation = [self expectationWithDescription:@"Device configuration changed was receieved"];
+    __block unsigned attributeReportsReceived = 0;
+    delegate.onAttributeDataReceived = ^(NSArray<NSDictionary<NSString *, id> *> * attributeReport) {
+        attributeReportsReceived += attributeReport.count;
+        XCTAssert(attributeReportsReceived > 0);
+        for (NSDictionary<NSString *, id> * attributeDict in attributeReport) {
+            MTRAttributePath * attributePath = attributeDict[MTRAttributePathKey];
+            XCTAssert(attributePath != nil);
+
+            XCTAssert(attributePath.cluster.unsignedLongValue == MTRClusterDescriptorID);
+            XCTAssert(attributePath.attribute.unsignedLongValue == MTRClusterDescriptorAttributePartsListID);
+
+            NSDictionary * dataValue = attributeDict[MTRDataKey];
+            XCTAssert(dataValue != nil);
+            NSArray<NSNumber *> * partsList = dataValue[MTRValueKey];
+            XCTAssert([partsList isEqual:(@[
+                                            @{
+                                                MTRDataKey : @ {
+                                                    MTRTypeKey : MTRUnsignedIntegerValueType,
+                                                    MTRValueKey : @1,
+                                                }
+                                            },
+                                            @{
+                                                MTRDataKey : @ {
+                                                    MTRTypeKey : MTRUnsignedIntegerValueType,
+                                                    MTRValueKey : @2,
+                                                }
+                                            },
+                                            @{
+                                                MTRDataKey : @ {
+                                                    MTRTypeKey : MTRUnsignedIntegerValueType,
+                                                    MTRValueKey : @3,
+                                                }
+                                            },
+                                        ])]);
+            [gotAttributeReportExpectation fulfill];
+        }
+    };
+
+    delegate.onReportEnd = ^() {
+        [gotAttributeReportEndExpectation fulfill];
+    };
+
+    delegate.onDeviceConfigurationChanged = ^() {
+        [deviceConfigurationChangedExpectation fulfill];
+    };
+
+    // Inject the attribute report with parts list changed.
+    [device unitTestInjectAttributeReport:@[ @{
+        MTRAttributePathKey : [MTRAttributePath attributePathWithEndpointID:@(0) clusterID:@(0x001D) attributeID:@(3)],
+        MTRDataKey : @{
+                MTRTypeKey : MTRArrayValueType,
+                MTRValueKey : @[
+                    @{
+                        MTRDataKey : @ {
+                            MTRTypeKey : MTRUnsignedIntegerValueType,
+                            MTRValueKey : @1,
+                        }
+                    },
+                    @{
+                        MTRDataKey : @ {
+                            MTRTypeKey : MTRUnsignedIntegerValueType,
+                            MTRValueKey : @2,
+                        }
+                    },
+                    @{
+                        MTRDataKey : @ {
+                            MTRTypeKey : MTRUnsignedIntegerValueType,
+                            MTRValueKey : @3,
+                        }
+                    },
+                ],
+        }}]];
+
+    [self waitForExpectations:@[ gotAttributeReportExpectation, gotAttributeReportEndExpectation, deviceConfigurationChangedExpectation ] timeout:60];
+}
+#endif
+
 @end
 
 @interface MTRDeviceEncoderTests : XCTestCase

src/darwin/Framework/CHIPTests/TestHelpers/MTRDeviceTestDelegate.h

@@ -30,6 +30,7 @@ typedef void (^MTRDeviceTestDelegateDataHandler)(NSArray<NSDictionary<NSString *
 @property (nonatomic, nullable) dispatch_block_t onDeviceCachePrimed;
 @property (nonatomic) BOOL skipExpectedValuesForWrite;
 @property (nonatomic) BOOL forceAttributeReportsIfMatchingCache;
+@property (nonatomic, nullable) dispatch_block_t onDeviceConfigurationChanged;
 @end
 
 NS_ASSUME_NONNULL_END

src/darwin/Framework/CHIPTests/TestHelpers/MTRDeviceTestDelegate.m

@@ -69,4 +69,13 @@ - (BOOL)unitTestForceAttributeReportsIfMatchingCache:(MTRDevice *)device
 {
     return self.forceAttributeReportsIfMatchingCache;
 }
+
+- (void)deviceConfigurationChanged:(MTRDevice *)device
+{
+    if (self.onDeviceConfigurationChanged != nil) {
+        self.onDeviceConfigurationChanged();
+    }
+}
+
+
 @end

src/darwin/Framework/CHIPTests/TestHelpers/MTRTestDeclarations.h

@@ -62,6 +62,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 @interface MTRDevice (TestDebug)
 - (void)unitTestInjectEventReport:(NSArray<NSDictionary<NSString *, id> *> *)eventReport;
+- (void)unitTestInjectAttributeReport:(NSArray<NSDictionary<NSString *, id> *> *)attributeReport;
 - (NSUInteger)unitTestAttributesReportedSinceLastCheck;
 @end
 #endif