content: /*
   * 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.streams.processor.internals.assignment;
  
  import org.apache.kafka.streams.processor.TaskId;
  import org.apache.kafka.streams.processor.assignment.AssignmentConfigs;
  import org.apache.kafka.streams.processor.assignment.ProcessId;
  
  import org.junit.jupiter.api.Test;
  
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.TreeMap;
  
  import static java.util.Arrays.asList;
  import static org.apache.kafka.streams.processor.internals.assignment.AssignmentTestUtils.EMPTY_RACK_AWARE_ASSIGNMENT_TAGS;
  import static org.apache.kafka.streams.processor.internals.assignment.AssignmentTestUtils.PID_1;
  import static org.apache.kafka.streams.processor.internals.assignment.AssignmentTestUtils.PID_2;
  import static org.apache.kafka.streams.processor.internals.assignment.AssignmentTestUtils.TASK_0_0;
  import static org.apache.kafka.streams.processor.internals.assignment.AssignmentTestUtils.TASK_0_1;
  import static org.apache.kafka.streams.processor.internals.assignment.AssignmentTestUtils.TASK_0_2;
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.hamcrest.Matchers.empty;
  import static org.hamcrest.Matchers.equalTo;
  import static org.hamcrest.Matchers.is;
  
  public class FallbackPriorTaskAssignorTest {
  
      private final Map<ProcessId, ClientState> clients = new TreeMap<>();
  
      @Test
      public void shouldViolateBalanceToPreserveActiveTaskStickiness() {
          final ClientState c1 = createClientWithPreviousActiveTasks(PID_1, 1, TASK_0_0, TASK_0_1, TASK_0_2);
          final ClientState c2 = createClient(PID_2, 1);
  
          final List<TaskId> taskIds = asList(TASK_0_0, TASK_0_1, TASK_0_2);
          Collections.shuffle(taskIds);
          final boolean probingRebalanceNeeded = new FallbackPriorTaskAssignor().assign(
              clients,
              new HashSet<>(taskIds),
              new HashSet<>(taskIds),
              null,
              new AssignmentConfigs(0L, 1, 0, 60_000L, EMPTY_RACK_AWARE_ASSIGNMENT_TAGS)
          );
          assertThat(probingRebalanceNeeded, is(true));
  
          assertThat(c1.activeTasks(), equalTo(Set.of(TASK_0_0, TASK_0_1, TASK_0_2)));
          assertThat(c2.activeTasks(), empty());
      }
  
      private ClientState createClient(final ProcessId processId, final int capacity) {
          return createClientWithPreviousActiveTasks(processId, capacity);
      }
  
      private ClientState createClientWithPreviousActiveTasks(final ProcessId processId, final int capacity, final TaskId... taskIds) {
          final ClientState clientState = new ClientState(capacity);
          clientState.addPreviousActiveTasks(Set.of(taskIds));
          clients.put(processId, clientState);
          return clientState;
      }
  }
  