package com.opencsv;
   
   import com.opencsv.exceptions.CsvValidationException;
   import org.junit.jupiter.api.*;
   
   import java.io.IOException;
   import java.util.Locale;
   import java.util.NoSuchElementException;
   
  import static org.junit.jupiter.api.Assertions.*;
  import static org.mockito.Mockito.mock;
  import static org.mockito.Mockito.when;
  
  public class CSVIteratorTest {
      private static final String[] STRINGS = {"test1", "test2"};
      private CSVIterator iterator;
      private CSVReader mockReader;
  
      private static Locale systemLocale;
  
      @BeforeAll
      public static void storeSystemLocale() {
          systemLocale = Locale.getDefault();
      }
  
      @AfterEach
      public void setSystemLocaleBackToDefault() {
          Locale.setDefault(systemLocale);
      }
  
      @BeforeEach
      public void setUp() throws IOException, CsvValidationException {
          Locale.setDefault(Locale.US);
          mockReader = mock(CSVReader.class);
          when(mockReader.readNext()).thenReturn(STRINGS);
          iterator = new CSVIterator(mockReader);
      }
  
      @Test
      public void readerExceptionCausesRunTimeException() throws IOException, CsvValidationException {
          when(mockReader.readNext()).thenThrow(new IOException("reader threw test exception"));
          Assertions.assertThrows(NoSuchElementException.class, () -> iterator.next());
      }
  
      @Test
      public void removeThrowsUnsupportedOperationException() {
          String englishErrorMessage = null;
          try {
              iterator.remove();
              fail("UnsupportedOperationException should have been thrown by read-only iterator.");
          }
          catch(UnsupportedOperationException e) {
              englishErrorMessage = e.getLocalizedMessage();
          }
          
          // Now with a different locale
          iterator.setErrorLocale(Locale.GERMAN);
          try {
              iterator.remove();
              fail("UnsupportedOperationException should have been thrown by read-only iterator.");
          }
          catch(UnsupportedOperationException e) {
              assertNotSame(englishErrorMessage, e.getLocalizedMessage());
          }
      }
  
      @Test
      public void initialReadReturnsStrings() {
          assertArrayEquals(STRINGS, iterator.next());
      }
  
      @Test
      public void hasNextWorks() throws IOException, CsvValidationException {
          when(mockReader.readNext()).thenReturn(null);
          assertTrue(iterator.hasNext()); // initial read from constructor
          iterator.next();
          assertFalse(iterator.hasNext());
      }
  }