/*
    * 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
    *
    *      https://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.commons.lang3.function;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertNull;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.function.Function;
  
  import org.apache.commons.lang3.StringUtils;
  import org.junit.jupiter.api.Test;
  
  /**
   * Tests {@link Functions}.
   */
  class FunctionsTest {
  
      /**
       * Tests {@link Functions#apply(Function, Object)}.
       */
      @Test
      void testApply() {
          final AtomicBoolean bool = new AtomicBoolean();
          assertFalse(Functions.apply(bool::getAndSet, true));
          assertTrue(bool.get());
          assertNull(Functions.apply(null, "foo"));
          assertNull(Functions.apply(null, null));
      }
  
      @Test
      void testApplyNonNull() {
          assertEquals("A", Functions.applyNonNull("a", String::toUpperCase));
          assertNull(Functions.applyNonNull((String) null, String::toUpperCase));
          assertNull(Functions.applyNonNull("a", s -> null));
          assertThrows(NullPointerException.class, () -> Functions.applyNonNull("a", null));
      }
  
      @Test
      void testApplyNonNull2() {
          assertEquals("A", Functions.applyNonNull(" a ", String::toUpperCase, String::trim));
          assertNull(Functions.applyNonNull((String) null, String::toUpperCase, String::trim));
          assertNull(Functions.applyNonNull(" a ", s -> null, String::trim));
          assertNull(Functions.applyNonNull(" a ", String::toUpperCase, s -> null));
          assertThrows(NullPointerException.class, () -> Functions.applyNonNull(" a ", null, String::trim));
          assertThrows(NullPointerException.class, () -> Functions.applyNonNull(" a ", String::toUpperCase, null));
      }
  
      @Test
      void testApplyNonNull3() {
          assertEquals("CBA", Functions.applyNonNull(" abc ", String::toUpperCase, String::trim, StringUtils::reverse));
          assertNull(Functions.applyNonNull((String) null, String::toUpperCase, String::trim, StringUtils::reverse));
          assertNull(Functions.applyNonNull(" abc ", s -> null, String::trim, StringUtils::reverse));
          assertNull(Functions.applyNonNull(" abc ", String::toUpperCase, s -> null, StringUtils::reverse));
          assertNull(Functions.applyNonNull(" abc ", String::toUpperCase, String::trim, s -> null));
          assertThrows(NullPointerException.class, () -> Functions.applyNonNull(" abc ", null, String::trim, StringUtils::reverse));
          assertThrows(NullPointerException.class, () -> Functions.applyNonNull(" abc ", String::toUpperCase, null, StringUtils::reverse));
          assertThrows(NullPointerException.class, () -> Functions.applyNonNull(" abc ", String::toUpperCase, String::trim, null));
      }
  
      /**
       * Tests {@link Functions#function(Function)}.
       */
      @Test
      void testFunction() {
          assertEquals("foo", Functions.function(String::valueOf).andThen(String::toString).apply("foo"));
      }
  }