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.beam.sdk.transforms;
  
  import java.io.Serializable;
  import java.util.function.Function;
  import org.apache.beam.sdk.util.SerializableUtils;
  import org.junit.Assert;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.junit.runners.JUnit4;
  
  /** Tests for {@link SerializableComparator}. */
  @RunWith(JUnit4.class)
  public class SerializableComparatorTest {
  
    /**
     * Tests if the {@link SerializableComparator} returned by {@link
     * SerializableComparator#comparing(SerializableFunction)} using {@link
     * SerializableUtils#ensureSerializable(Serializable)}.
     */
    @Test
    public void testSerializable() {
      SerializableFunction<String, Integer> fn = Integer::parseInt;
  
      SerializableComparator<String> cmp = SerializableComparator.comparing(fn);
      SerializableUtils.ensureSerializable(cmp);
    }
  
    /**
     * Tests if {@link SerializableComparator#comparing(Function)} throws a {@link
     * java.lang.NullPointerException} if <code>null</code> is passed to it.
     */
    @Test(expected = NullPointerException.class)
    public void testIfNPEThrownForNullFunction() {
      SerializableComparator.comparing(null);
    }
  
    /** Tests the basic comparison function of the {@link SerializableComparator} returned. */
    @Test
    public void testBasicComparison() {
      SerializableFunction<String, Integer> fn = Integer::parseInt;
      SerializableComparator<String> cmp = SerializableComparator.comparing(fn);
  
      Assert.assertTrue(cmp.compare("1", "10") < 0);
      Assert.assertTrue(cmp.compare("9", "6") > 0);
    }
  }
  