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.Assert.assertEquals;
021import static org.junit.Assert.assertNotEquals;
022import static org.mockito.Mockito.mock;
023
024import org.apache.hadoop.hbase.HBaseClassTestRule;
025import org.apache.hadoop.hbase.testclassification.SmallTests;
026import org.junit.ClassRule;
027import org.junit.Test;
028import org.junit.experimental.categories.Category;
029
030import org.apache.hbase.thirdparty.com.google.common.collect.Lists;
031
032/**
033 * Test class for {@link MetricRegistriesLoader}.
034 */
035@Category(SmallTests.class)
036public class TestMetricRegistriesLoader {
037
038  @ClassRule
039  public static final HBaseClassTestRule CLASS_RULE =
040    HBaseClassTestRule.forClass(TestMetricRegistriesLoader.class);
041
042  @Test
043  public void testLoadSinleInstance() {
044    MetricRegistries loader = mock(MetricRegistries.class);
045    MetricRegistries instance = MetricRegistriesLoader.load(Lists.newArrayList(loader));
046    assertEquals(loader, instance);
047  }
048
049  @Test
050  public void testLoadMultipleInstances() {
051    MetricRegistries loader1 = mock(MetricRegistries.class);
052    MetricRegistries loader2 = mock(MetricRegistries.class);
053    MetricRegistries loader3 = mock(MetricRegistries.class);
054    MetricRegistries instance =
055      MetricRegistriesLoader.load(Lists.newArrayList(loader1, loader2, loader3));
056
057    // the load() returns the first instance
058    assertEquals(loader1, instance);
059    assertNotEquals(loader2, instance);
060    assertNotEquals(loader3, instance);
061  }
062}