001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.metrics;
019
020import static org.junit.jupiter.api.Assertions.assertEquals;
021import static org.junit.jupiter.api.Assertions.assertNotEquals;
022import static org.mockito.Mockito.mock;
023
024import org.apache.hadoop.hbase.testclassification.SmallTests;
025import org.junit.jupiter.api.Tag;
026import org.junit.jupiter.api.Test;
027
028import org.apache.hbase.thirdparty.com.google.common.collect.Lists;
029
030/**
031 * Test class for {@link MetricRegistriesLoader}.
032 */
033@Tag(SmallTests.TAG)
034public class TestMetricRegistriesLoader {
035
036  @Test
037  public void testLoadSingleInstance() {
038    MetricRegistries loader = mock(MetricRegistries.class);
039    MetricRegistries instance = MetricRegistriesLoader.load(Lists.newArrayList(loader));
040    assertEquals(loader, instance);
041  }
042
043  @Test
044  public void testLoadMultipleInstances() {
045    MetricRegistries loader1 = mock(MetricRegistries.class);
046    MetricRegistries loader2 = mock(MetricRegistries.class);
047    MetricRegistries loader3 = mock(MetricRegistries.class);
048    MetricRegistries instance =
049      MetricRegistriesLoader.load(Lists.newArrayList(loader1, loader2, loader3));
050
051    // the load() returns the first instance
052    assertEquals(loader1, instance);
053    assertNotEquals(loader2, instance);
054    assertNotEquals(loader3, instance);
055  }
056}