dajac commented on code in PR #13443: URL: https://github.com/apache/kafka/pull/13443#discussion_r1170981380
########## group-coordinator/src/test/java/org/apache/kafka/coordinator/group/assignor/RangeAssignorTest.java: ########## @@ -0,0 +1,416 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.kafka.coordinator.group.assignor; + +import org.apache.kafka.common.Uuid; + +import org.junit.jupiter.api.Test; + +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.Optional; +import java.util.Set; + +import static org.junit.jupiter.api.Assertions.assertEquals; +import static org.junit.jupiter.api.Assertions.assertNull; +import static org.junit.jupiter.api.Assertions.assertTrue; + +public class RangeAssignorTest { + private final RangeAssignor assignor = new RangeAssignor(); + private final Uuid topic1Uuid = Uuid.randomUuid(); + private final Uuid topic2Uuid = Uuid.randomUuid(); + private final Uuid topic3Uuid = Uuid.randomUuid(); + private final String consumerA = "A"; + private final String consumerB = "B"; + private final String consumerC = "C"; + + @Test + public void testOneConsumerNoTopic() { + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + topics.put(topic1Uuid, new AssignmentTopicMetadata(3)); + Map<String, AssignmentMemberSpec> members = new HashMap<>(); + List<Uuid> subscribedTopics = new ArrayList<>(); + members.computeIfAbsent(consumerA, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopics, new HashMap<>())); + + AssignmentSpec assignmentSpec = new AssignmentSpec(members, topics); + GroupAssignment groupAssignment = assignor.assign(assignmentSpec); + + assertTrue(groupAssignment.members().isEmpty()); + } + + @Test + public void testOneConsumerNonExistentTopic() { + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + topics.put(topic1Uuid, new AssignmentTopicMetadata(3)); + Map<String, AssignmentMemberSpec> members = new HashMap<>(); + List<Uuid> subscribedTopics = new ArrayList<>(); + subscribedTopics.add(topic2Uuid); + members.computeIfAbsent(consumerA, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopics, new HashMap<>())); + + AssignmentSpec assignmentSpec = new AssignmentSpec(members, topics); + GroupAssignment groupAssignment = assignor.assign(assignmentSpec); + + assertTrue(groupAssignment.members().isEmpty()); + } + + @Test + public void testFirstAssignmentTwoConsumersTwoTopicsSameSubscriptions() { + // A -> T1, T3 // B -> T1, T3 // T1 -> 3 Partitions // T3 -> 2 Partitions + // Topics + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + topics.put(topic1Uuid, new AssignmentTopicMetadata(3)); + topics.put(topic3Uuid, new AssignmentTopicMetadata(2)); + // Members + Map<String, AssignmentMemberSpec> members = new HashMap<>(); + // Consumer A + List<Uuid> subscribedTopicsA = new ArrayList<>(Arrays.asList(topic1Uuid, topic3Uuid)); + members.put(consumerA, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsA, new HashMap<>())); + // Consumer B + List<Uuid> subscribedTopicsB = new ArrayList<>(Arrays.asList(topic1Uuid, topic3Uuid)); + members.put(consumerB, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsB, new HashMap<>())); + + AssignmentSpec assignmentSpec = new AssignmentSpec(members, topics); + GroupAssignment computedAssignment = assignor.assign(assignmentSpec); + + Map<Uuid, Set<Set<Integer>>> expectedAssignment = new HashMap<>(); + // Topic 1 Partitions Assignment + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(0, 1))); + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(2))); + // Topic 3 Partitions Assignment + expectedAssignment.computeIfAbsent(topic3Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(0))); + expectedAssignment.computeIfAbsent(topic3Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(1))); + + assertAssignment(expectedAssignment, computedAssignment); + } + + @Test + public void testFirstAssignmentThreeConsumersThreeTopicsDifferentSubscriptions() { + // A -> T1, T2 // B -> T3 // C -> T2, T3 // T1 -> 3 Partitions // T2 -> 3 Partitions // T3 -> 2 Partitions + // Topics + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + topics.put(topic1Uuid, new AssignmentTopicMetadata(3)); + topics.put(topic2Uuid, new AssignmentTopicMetadata(3)); + topics.put(topic3Uuid, new AssignmentTopicMetadata(2)); + // Members + Map<String, AssignmentMemberSpec> members = new HashMap<>(); + // Consumer A + List<Uuid> subscribedTopicsA = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid)); + members.put(consumerA, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsA, new HashMap<>())); + // Consumer B + List<Uuid> subscribedTopicsB = new ArrayList<>(Collections.singletonList(topic3Uuid)); + members.put(consumerB, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsB, new HashMap<>())); + // Consumer C + List<Uuid> subscribedTopicsC = new ArrayList<>(Arrays.asList(topic2Uuid, topic3Uuid)); + members.put(consumerC, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsC, new HashMap<>())); + + AssignmentSpec assignmentSpec = new AssignmentSpec(members, topics); + GroupAssignment computedAssignment = assignor.assign(assignmentSpec); + + Map<Uuid, Set<Set<Integer>>> expectedAssignment = new HashMap<>(); + // Topic 1 Partitions Assignment + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(0, 1, 2))); + // Topic 2 Partitions Assignment + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(0, 1))); + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(2))); + // Topic 3 Partitions Assignment + expectedAssignment.computeIfAbsent(topic3Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(0))); + expectedAssignment.computeIfAbsent(topic3Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(1))); + + assertAssignment(expectedAssignment, computedAssignment); + } + + @Test + public void testFirstAssignmentNumConsumersGreaterThanNumPartitions() { + // Topics + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + topics.put(topic1Uuid, new AssignmentTopicMetadata(3)); + // Topic 3 has 2 partitions but three consumers subscribed to it - one of them will not get an assignment + topics.put(topic3Uuid, new AssignmentTopicMetadata(2)); + // Members + Map<String, AssignmentMemberSpec> members = new HashMap<>(); + // Consumer A + List<Uuid> subscribedTopicsA = new ArrayList<>(Arrays.asList(topic1Uuid, topic3Uuid)); + members.put(consumerA, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsA, new HashMap<>())); + // Consumer B + List<Uuid> subscribedTopicsB = new ArrayList<>(Arrays.asList(topic1Uuid, topic3Uuid)); + members.put(consumerB, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsB, new HashMap<>())); + // Consumer C + List<Uuid> subscribedTopicsC = new ArrayList<>(Arrays.asList(topic1Uuid, topic3Uuid)); + members.put(consumerC, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsC, new HashMap<>())); + + AssignmentSpec assignmentSpec = new AssignmentSpec(members, topics); + GroupAssignment computedAssignment = assignor.assign(assignmentSpec); + + Map<Uuid, Set<Set<Integer>>> expectedAssignment = new HashMap<>(); + // Topic 1 Partitions Assignment + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(0))); + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(1))); + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(2))); + // Topic 2 Partitions Assignment + expectedAssignment.computeIfAbsent(topic3Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(0))); + expectedAssignment.computeIfAbsent(topic3Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(1))); + + assertAssignment(expectedAssignment, computedAssignment); + } + + @Test + public void testReassignmentNumConsumersGreaterThanNumPartitionsWhenOneConsumerAdded() { + // Topics + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + topics.put(topic1Uuid, new AssignmentTopicMetadata(2)); + topics.put(topic2Uuid, new AssignmentTopicMetadata(2)); + // Members + Map<String, AssignmentMemberSpec> members = new HashMap<>(); + // Add a new consumer to trigger a re-assignment + // Consumer C + List<Uuid> subscribedTopicsC = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid)); + members.put(consumerC, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsC, new HashMap<>())); + // Consumer A + List<Uuid> subscribedTopicsA = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid)); + Map<Uuid, Set<Integer>> currentAssignmentForA = new HashMap<>(); + currentAssignmentForA.put(topic1Uuid, new HashSet<>(Collections.singletonList(0))); + currentAssignmentForA.put(topic2Uuid, new HashSet<>(Collections.singletonList(0))); + members.computeIfAbsent(consumerA, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsA, currentAssignmentForA)); + // Consumer B + List<Uuid> subscribedTopicsB = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid)); + Map<Uuid, Set<Integer>> currentAssignmentForB = new HashMap<>(); + currentAssignmentForB.put(topic1Uuid, new HashSet<>(Collections.singletonList(1))); + currentAssignmentForB.put(topic2Uuid, new HashSet<>(Collections.singletonList(1))); + members.computeIfAbsent(consumerB, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsB, currentAssignmentForB)); + + AssignmentSpec assignmentSpec = new AssignmentSpec(members, topics); + GroupAssignment computedAssignment = assignor.assign(assignmentSpec); + + Map<Uuid, Set<Set<Integer>>> expectedAssignment = new HashMap<>(); + // Topic 1 Partitions Assignment + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(0))); + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(1))); + // Topic 2 Partitions Assignment + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(0))); + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(1))); + + // Test for stickiness + assertEquals(computedAssignment.members().get(consumerA).targetPartitions(), new HashMap<>(currentAssignmentForA), "Stickiness test failed for Consumer A"); + assertEquals(computedAssignment.members().get(consumerB).targetPartitions(), new HashMap<>(currentAssignmentForB), "Stickiness test failed for Consumer B"); + + // Consumer C shouldn't get any assignment, due to stickiness A, B retain their assignments + assertNull(computedAssignment.members().get(consumerC)); + assertAssignment(expectedAssignment, computedAssignment); + assertCoPartitionJoinProperty(computedAssignment); + } + + @Test + public void testReassignmentWhenOnePartitionAddedForTwoConsumersTwoTopics() { + // T1, T2 both have 3 partitions each when first assignment was calculated -> currentAssignmentForX + Map<String, AssignmentMemberSpec> members = new HashMap<>(); + // Consumer A + List<Uuid> subscribedTopicsA = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid)); + Map<Uuid, Set<Integer>> currentAssignmentForA = new HashMap<>(); + currentAssignmentForA.put(topic1Uuid, new HashSet<>(Arrays.asList(0, 1))); + currentAssignmentForA.put(topic2Uuid, new HashSet<>(Arrays.asList(0, 1))); + members.computeIfAbsent(consumerA, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsA, currentAssignmentForA)); + + // Consumer B + List<Uuid> subscribedTopicsB = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid)); + Map<Uuid, Set<Integer>> currentAssignmentForB = new HashMap<>(); + currentAssignmentForB.put(topic1Uuid, new HashSet<>(Collections.singletonList(2))); + currentAssignmentForB.put(topic2Uuid, new HashSet<>(Collections.singletonList(2))); + members.computeIfAbsent(consumerB, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsB, currentAssignmentForB)); + + // Simulating adding a partition - originally T1 -> 3 Partitions and T2 -> 3 Partitions + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + topics.put(topic1Uuid, new AssignmentTopicMetadata(4)); + topics.put(topic2Uuid, new AssignmentTopicMetadata(4)); + + AssignmentSpec assignmentSpec = new AssignmentSpec(members, topics); + GroupAssignment computedAssignment = assignor.assign(assignmentSpec); + + Map<Uuid, Set<Set<Integer>>> expectedAssignment = new HashMap<>(); + // Topic 1 Partitions Assignment + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(0, 1))); + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(2, 3))); + // Topic 2 Partitions Assignment + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(0, 1))); + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(2, 3))); + + // Test for stickiness + assertEquals(computedAssignment.members().get(consumerA).targetPartitions(), new HashMap<>(currentAssignmentForA), "Stickiness test failed for Consumer A"); + // Implicitly B also retained its partitions since the other set of assigned partitions is (2,3) + + assertAssignment(expectedAssignment, computedAssignment); + assertCoPartitionJoinProperty(computedAssignment); + } + + @Test + public void testReassignmentWhenOneConsumerAddedAfterInitialAssignmentWithTwoConsumersTwoTopics() { + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + topics.put(topic1Uuid, new AssignmentTopicMetadata(3)); + topics.put(topic2Uuid, new AssignmentTopicMetadata(3)); + + Map<String, AssignmentMemberSpec> members = new HashMap<>(); + // Consumer A + List<Uuid> subscribedTopicsA = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid)); + Map<Uuid, Set<Integer>> currentAssignmentForA = new HashMap<>(); + currentAssignmentForA.put(topic1Uuid, new HashSet<>(Arrays.asList(0, 1))); + currentAssignmentForA.put(topic2Uuid, new HashSet<>(Arrays.asList(0, 1))); + members.computeIfAbsent(consumerA, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsA, currentAssignmentForA)); + // Consumer B + List<Uuid> subscribedTopicsB = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid)); + Map<Uuid, Set<Integer>> currentAssignmentForB = new HashMap<>(); + currentAssignmentForB.put(topic1Uuid, new HashSet<>(Collections.singletonList(2))); + currentAssignmentForB.put(topic2Uuid, new HashSet<>(Collections.singletonList(2))); + members.computeIfAbsent(consumerB, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsB, currentAssignmentForB)); + // Add a new consumer to trigger a re-assignment + // Consumer C + List<Uuid> subscribedTopicsC = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid)); + members.put(consumerC, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsC, new HashMap<>())); + + AssignmentSpec assignmentSpec = new AssignmentSpec(members, topics); + GroupAssignment computedAssignment = assignor.assign(assignmentSpec); + + Map<Uuid, Set<Set<Integer>>> expectedAssignment = new HashMap<>(); + // Topic 1 Partitions Assignment + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(0))); + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(2))); + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(1))); + // Topic 2 Partitions Assignment + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(0))); + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(2))); + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(1))); + + // Test for stickiness + assertEquals(computedAssignment.members().get(consumerB).targetPartitions(), new HashMap<>(currentAssignmentForB), "Stickiness test failed for Consumer B"); + assertTrue(computedAssignment.members().get(consumerA).targetPartitions().get(topic1Uuid).contains(0), "Stickiness test failed for Consumer A"); + // Co-partition join property test ensures that A retained the same partition for all topics. + + assertAssignment(expectedAssignment, computedAssignment); + assertCoPartitionJoinProperty(computedAssignment); + } + + @Test + public void testReassignmentWhenOneConsumerRemovedAfterInitialAssignmentWithTwoConsumersTwoTopics() { + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + topics.put(topic1Uuid, new AssignmentTopicMetadata(3)); + topics.put(topic2Uuid, new AssignmentTopicMetadata(3)); + + Map<String, AssignmentMemberSpec> members = new HashMap<>(); + // Consumer A was removed + + // Consumer B + List<Uuid> subscribedTopicsB = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid)); + Map<Uuid, Set<Integer>> currentAssignmentForB = new HashMap<>(); + currentAssignmentForB.put(topic1Uuid, new HashSet<>(Collections.singletonList(2))); + currentAssignmentForB.put(topic2Uuid, new HashSet<>(Collections.singletonList(2))); + members.computeIfAbsent(consumerB, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsB, currentAssignmentForB)); + + AssignmentSpec assignmentSpec = new AssignmentSpec(members, topics); + GroupAssignment computedAssignment = assignor.assign(assignmentSpec); + + Map<Uuid, Set<Set<Integer>>> expectedAssignment = new HashMap<>(); + // Topic 1 Partitions Assignment + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(0, 1, 2))); + // Topic 2 Partitions Assignment + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(0, 1, 2))); + + assertAssignment(expectedAssignment, computedAssignment); + assertCoPartitionJoinProperty(computedAssignment); + } + + @Test + public void testReassignmentWhenMultipleSubscriptionsRemovedAfterInitialAssignmentWithThreeConsumersTwoTopics() { + + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + topics.put(topic1Uuid, new AssignmentTopicMetadata(3)); + topics.put(topic2Uuid, new AssignmentTopicMetadata(3)); + topics.put(topic3Uuid, new AssignmentTopicMetadata(2)); + + // Let initial subscriptions be A -> T1, T2 // B -> T2 // C -> T2, T3 + // Change the subscriptions to A -> T1 // B -> T1, T2, T3 // C -> T2 + Map<String, AssignmentMemberSpec> members = new HashMap<>(); + // Consumer A + Map<Uuid, Set<Integer>> currentAssignmentForA = new HashMap<>(); + currentAssignmentForA.put(topic1Uuid, new HashSet<>(Arrays.asList(0, 1, 2))); + currentAssignmentForA.put(topic2Uuid, new HashSet<>(Collections.singletonList(0))); + // Change subscriptions + List<Uuid> subscribedTopicsA = new ArrayList<>(Collections.singletonList(topic1Uuid)); + members.computeIfAbsent(consumerA, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsA, currentAssignmentForA)); + // Consumer B + Map<Uuid, Set<Integer>> currentAssignmentForB = new HashMap<>(); + currentAssignmentForB.put(topic2Uuid, new HashSet<>(Collections.singletonList(1))); + // Change subscriptions + List<Uuid> subscribedTopicsB = new ArrayList<>(Arrays.asList(topic1Uuid, topic2Uuid, topic3Uuid)); + members.computeIfAbsent(consumerB, k -> new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsB, currentAssignmentForB)); + // Consumer C + Map<Uuid, Set<Integer>> currentAssignmentForC = new HashMap<>(); + currentAssignmentForC.put(topic2Uuid, new HashSet<>(Collections.singletonList(2))); + currentAssignmentForC.put(topic3Uuid, new HashSet<>(Arrays.asList(0, 1))); + // Change subscriptions + List<Uuid> subscribedTopicsC = new ArrayList<>(Collections.singletonList(topic2Uuid)); + members.put(consumerC, new AssignmentMemberSpec(Optional.empty(), Optional.empty(), subscribedTopicsC, new HashMap<>())); + + AssignmentSpec assignmentSpec = new AssignmentSpec(members, topics); + GroupAssignment computedAssignment = assignor.assign(assignmentSpec); + + Map<Uuid, Set<Set<Integer>>> expectedAssignment = new HashMap<>(); + // Topic 1 Partitions Assignment + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(0, 1))); + expectedAssignment.computeIfAbsent(topic1Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(2))); + // Topic 2 Partitions Assignment + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(0, 1))); + expectedAssignment.computeIfAbsent(topic2Uuid, k -> new HashSet<>()).add(new HashSet<>(Collections.singletonList(2))); + // Topic 3 Partitions Assignment + expectedAssignment.computeIfAbsent(topic3Uuid, k -> new HashSet<>()).add(new HashSet<>(Arrays.asList(0, 1))); + + // Test for stickiness + assertTrue(computedAssignment.members().get(consumerC).targetPartitions().get(topic2Uuid).contains(2), "Stickiness test failed for Consumer C"); + assertTrue(computedAssignment.members().get(consumerA).targetPartitions().get(topic1Uuid).containsAll(Arrays.asList(0, 1)), "Stickiness test failed for Consumer A"); + + assertAssignment(expectedAssignment, computedAssignment); Review Comment: gotcha. i understand what you meant now. -- This is an automated message from the Apache Git Service. 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