code: /*
   * 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.skywalking.oap.server.core.analysis;
  
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.params.ParameterizedTest;
  import org.junit.jupiter.params.provider.MethodSource;
  
  import java.util.Calendar;
  import java.util.TimeZone;
  
  public class TimeBucketTest {
      private static final long NOW = System.currentTimeMillis();
  
      public static Object[] parameters() {
          return new Object[]{
                  DownSampling.Second,
                  DownSampling.Minute,
                  DownSampling.Hour,
                  DownSampling.Day
          };
      }
  
      @ParameterizedTest
      @MethodSource("parameters")
      public void testConversion(DownSampling downSampling) {
          long timestamp = TimeBucket.getTimestamp(TimeBucket.getTimeBucket(NOW, downSampling));
  
          Calendar instance = Calendar.getInstance(TimeZone.getDefault());
          instance.setTimeInMillis(NOW);
          switch (downSampling) {
              case Day: {
                  instance.set(Calendar.HOUR_OF_DAY, 0);
                  // Fall through
              }
              case Hour: {
                  instance.set(Calendar.MINUTE, 0);
                  // Fall through
              }
              case Minute: {
                  instance.set(Calendar.SECOND, 0);
                  // Fall through
              }
              case Second: {
                  instance.set(Calendar.MILLISECOND, 0);
                  // Fall through
              }
          }
          Assertions.assertEquals(instance.getTimeInMillis(), timestamp);
      }
  }
  