text: /*
   * 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.metrics;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import org.junit.Before;
  import org.junit.Test;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertNull;
  import static org.junit.Assert.assertThrows;
  
  public class KafkaMetricsContextTest {
  
      private static final String SAMPLE_NAMESPACE = "sample-ns";
  
      private static final String LABEL_A_KEY = "label-a";
      private static final String LABEL_A_VALUE = "label-a-value";
  
      private String namespace;
      private Map<String, String> labels;
      private KafkaMetricsContext context;
  
      @Before
      public void beforeEach() {
          namespace = SAMPLE_NAMESPACE;
          labels = new HashMap<>();
          labels.put(LABEL_A_KEY, LABEL_A_VALUE);
      }
  
      @Test
      public void testCreationWithValidNamespaceAndNoLabels() {
          labels.clear();
          context = new KafkaMetricsContext(namespace, labels);
  
          assertEquals(1, context.contextLabels().size());
          assertEquals(namespace, context.contextLabels().get(MetricsContext.NAMESPACE));
      }
  
      @Test
      public void testCreationWithValidNamespaceAndLabels() {
          context = new KafkaMetricsContext(namespace, labels);
  
          assertEquals(2, context.contextLabels().size());
          assertEquals(namespace, context.contextLabels().get(MetricsContext.NAMESPACE));
          assertEquals(LABEL_A_VALUE, context.contextLabels().get(LABEL_A_KEY));
      }
  
      @Test
      public void testCreationWithValidNamespaceAndNullLabelValues() {
          labels.put(LABEL_A_KEY, null);
          context = new KafkaMetricsContext(namespace, labels);
  
          assertEquals(2, context.contextLabels().size());
          assertEquals(namespace, context.contextLabels().get(MetricsContext.NAMESPACE));
          assertNull(context.contextLabels().get(LABEL_A_KEY));
      }
  
      @Test
      public void testCreationWithNullNamespaceAndLabels() {
          context = new KafkaMetricsContext(null, labels);
  
          assertEquals(2, context.contextLabels().size());
          assertNull(context.contextLabels().get(MetricsContext.NAMESPACE));
          assertEquals(LABEL_A_VALUE, context.contextLabels().get(LABEL_A_KEY));
      }
  
      @Test
      public void testKafkaMetricsContextLabelsAreImmutable() {
          context = new KafkaMetricsContext(namespace, labels);
          assertThrows(UnsupportedOperationException.class, () -> context.contextLabels().clear());
      }
  }