/*
    * 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.apache.commons.lang3.LangAssertions.assertNullPointerException;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertNotNull;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  
  import java.io.IOException;
  
  import org.apache.commons.lang3.AbstractLangTest;
  import org.junit.jupiter.api.Test;
  
  /**
   * Tests {@link FailableDoubleUnaryOperator}.
   */
  class FailableDoubleUnaryOperatorTest extends AbstractLangTest {
  
      @Test
      void testAndThen_composesCorrectly() throws IOException {
          final FailableDoubleUnaryOperator<IOException> times2 = v -> v * 2;
          final FailableDoubleUnaryOperator<IOException> plus1 = v -> v + 1;
          assertEquals(7.0, times2.andThen(plus1).applyAsDouble(3.0));
      }
  
      @Test
      void testAndThen_nullAfter_throwsNullPointerException() throws Throwable {
          final FailableDoubleUnaryOperator<IOException> op = v -> v;
          assertNullPointerException(() -> op.andThen(null));
      }
  
      @Test
      void testApplyAsDouble_returnsResult() throws IOException {
          final FailableDoubleUnaryOperator<IOException> op = v -> v * 2;
          assertEquals(6.0, op.applyAsDouble(3.0));
      }
  
      @Test
      void testApplyAsDouble_throwsException() {
          final IOException expected = new IOException("fail");
          final FailableDoubleUnaryOperator<IOException> op = v -> {
              throw expected;
          };
          final IOException thrown = assertThrows(IOException.class, () -> op.applyAsDouble(1.0));
          assertEquals(expected, thrown);
      }
  
      @Test
      void testCompose_composesCorrectly() throws IOException {
          final FailableDoubleUnaryOperator<IOException> times2 = v -> v * 2;
          final FailableDoubleUnaryOperator<IOException> plus1 = v -> v + 1;
          assertEquals(8.0, times2.compose(plus1).applyAsDouble(3.0));
      }
  
      @Test
      void testCompose_nullBefore_throwsNullPointerException() throws Throwable {
          final FailableDoubleUnaryOperator<IOException> op = v -> v;
          assertNullPointerException(() -> op.compose(null));
      }
  
      @Test
      void testIdentity_returnsInput() throws IOException {
          assertEquals(3.14, FailableDoubleUnaryOperator.<IOException>identity().applyAsDouble(3.14));
      }
  
      @Test
      void testNop_applyAsDoubleReturnsZero() throws Throwable {
          assertEquals(0d, FailableDoubleUnaryOperator.nop().applyAsDouble(5.0));
      }
  
      @Test
      void testNop_returnsNonNull() {
          assertNotNull(FailableDoubleUnaryOperator.nop());
      }
  }