package com.opencsv.bean;
   
   import com.opencsv.bean.mocks.OptionalMock;
   import com.opencsv.exceptions.CsvDataTypeMismatchException;
   import com.opencsv.exceptions.CsvRequiredFieldEmptyException;
   import org.apache.commons.lang3.StringUtils;
   import org.junit.jupiter.api.Test;
   
   import java.io.StringReader;
  import java.io.StringWriter;
  import java.io.Writer;
  import java.util.List;
  import java.util.Optional;
  
  import static org.junit.jupiter.api.Assertions.*;
  
  /**
   * Tests that accessor methods using {@link java.util.Optional} function
   * correctly.
   */
  public class OptionalTest {
  
      @Test
      public void testReadWithOptionalNull() {
          List<OptionalMock> beans = new CsvToBeanBuilder<OptionalMock>(new StringReader("field\n\n"))
                  .withType(OptionalMock.class)
                  .build().parse();
          assertNotNull(beans);
          assertEquals(1, beans.size());
          OptionalMock b = beans.get(0);
          Optional<String> s = b.getField();
          assertNotNull(s);
          assertTrue(s.isPresent());
          assertEquals(StringUtils.EMPTY, s.get());
      }
  
      @Test
      public void testReadWithOptionalNotNull() {
          List<OptionalMock> beans = new CsvToBeanBuilder<OptionalMock>(new StringReader("field\nstr\n"))
                  .withType(OptionalMock.class)
                  .build().parse();
          assertNotNull(beans);
          assertEquals(1, beans.size());
          OptionalMock b = beans.get(0);
          Optional<String> s = b.getField();
          assertNotNull(s);
          assertTrue(s.isPresent());
          assertEquals("str", s.get());
      }
  
      @Test
      public void testWriteWithOptionalNull() throws CsvDataTypeMismatchException, CsvRequiredFieldEmptyException {
          OptionalMock b = new OptionalMock();
          b.setField(Optional.empty());
          Writer w = new StringWriter();
          StatefulBeanToCsv<OptionalMock> b2csv = new StatefulBeanToCsvBuilder<OptionalMock>(w)
                  .withApplyQuotesToAll(false)
                  .build();
          b2csv.write(b);
          assertEquals("FIELD\n\n", w.toString());
      }
  
      @Test
      public void testWriteWithOptionalNotNull() throws CsvDataTypeMismatchException, CsvRequiredFieldEmptyException {
          OptionalMock b = new OptionalMock();
          b.setField(Optional.of("str"));
          Writer w = new StringWriter();
          StatefulBeanToCsv<OptionalMock> b2csv = new StatefulBeanToCsvBuilder<OptionalMock>(w)
                  .withApplyQuotesToAll(false)
                  .build();
          b2csv.write(b);
          assertEquals("FIELD\nstr\n", w.toString());
      }
  }