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.kafka.streams.state.internals;
  
  import org.junit.jupiter.api.Test;
  
  import java.util.NoSuchElementException;
  
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.hamcrest.Matchers.is;
  import static org.hamcrest.Matchers.nullValue;
  import static org.junit.jupiter.api.Assertions.fail;
  
  public class MaybeTest {
      @Test
      public void shouldReturnDefinedValue() {
          assertThat(Maybe.defined(null).getNullableValue(), nullValue());
          assertThat(Maybe.defined("ASDF").getNullableValue(), is("ASDF"));
      }
  
      @Test
      public void shouldAnswerIsDefined() {
          assertThat(Maybe.defined(null).isDefined(), is(true));
          assertThat(Maybe.defined("ASDF").isDefined(), is(true));
          assertThat(Maybe.undefined().isDefined(), is(false));
      }
  
      @Test
      public void shouldThrowOnGetUndefinedValue() {
          final Maybe<Object> undefined = Maybe.undefined();
          try {
              undefined.getNullableValue();
              fail();
          } catch (final NoSuchElementException e) {
              // no assertion necessary
          }
      }
  
      @Test
      public void shouldUpholdEqualityCorrectness() {
          assertThat(Maybe.undefined().equals(Maybe.undefined()), is(true));
          assertThat(Maybe.defined(null).equals(Maybe.defined(null)), is(true));
          assertThat(Maybe.defined("q").equals(Maybe.defined("q")), is(true));
  
          assertThat(Maybe.undefined().equals(Maybe.defined(null)), is(false));
          assertThat(Maybe.undefined().equals(Maybe.defined("x")), is(false));
  
          assertThat(Maybe.defined(null).equals(Maybe.undefined()), is(false));
          assertThat(Maybe.defined(null).equals(Maybe.defined("x")), is(false));
  
          assertThat(Maybe.defined("a").equals(Maybe.undefined()), is(false));
          assertThat(Maybe.defined("a").equals(Maybe.defined(null)), is(false));
          assertThat(Maybe.defined("a").equals(Maybe.defined("b")), is(false));
      }
  
      @Test
      public void shouldUpholdHashCodeCorrectness() {
          // This specifies the current implementation, which is simpler to write than an exhaustive test.
          // As long as this implementation doesn't change, then the equals/hashcode contract is upheld.
  
          assertThat(Maybe.undefined().hashCode(), is(-1));
          assertThat(Maybe.defined(null).hashCode(), is(0));
          assertThat(Maybe.defined("a").hashCode(), is("a".hashCode()));
      }
  }
  