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.common.utils;
  
  import org.junit.jupiter.api.Test;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import static org.apache.kafka.common.utils.CollectionUtils.subtractMap;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertNotSame;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  public class CollectionUtilsTest {
  
      @Test
      public void testSubtractMapRemovesSecondMapsKeys() {
          Map<String, String> mainMap = new HashMap<>();
          mainMap.put("one", "1");
          mainMap.put("two", "2");
          mainMap.put("three", "3");
          Map<String, String> secondaryMap = new HashMap<>();
          secondaryMap.put("one", "4");
          secondaryMap.put("two", "5");
  
          Map<String, String> newMap = subtractMap(mainMap, secondaryMap);
  
          assertEquals(3, mainMap.size());  // original map should not be modified
          assertEquals(1, newMap.size());
          assertTrue(newMap.containsKey("three"));
          assertEquals("3", newMap.get("three"));
      }
  
      @Test
      public void testSubtractMapDoesntRemoveAnythingWhenEmptyMap() {
          Map<String, String> mainMap = new HashMap<>();
          mainMap.put("one", "1");
          mainMap.put("two", "2");
          mainMap.put("three", "3");
          Map<String, String> secondaryMap = new HashMap<>();
  
          Map<String, String> newMap = subtractMap(mainMap, secondaryMap);
  
          assertEquals(3, newMap.size());
          assertEquals("1", newMap.get("one"));
          assertEquals("2", newMap.get("two"));
          assertEquals("3", newMap.get("three"));
          assertNotSame(newMap, mainMap);
      }
  }
  