EntrySetIterator.java

/*
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * 2 along with this work; if not, write to the Free Software Foundation,
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/*
 * @test
 * @bug 8139233
 * @summary ensure entry set's iterator doesn't have side effects on the entry set
 * @run testng EntrySetIterator
 */

import java.util.*;
import org.testng.annotations.Test;
import static org.testng.Assert.assertTrue;
import static org.testng.Assert.assertEquals;

public class EntrySetIterator {
    @Test
    public void main() {
        Map<String, String> map = Map.of("a", "1", "b", "2", "c", "3");
        Set<Map.Entry<String, String>> entrySet = map.entrySet();
        Iterator<Map.Entry<String, String>> iterator = entrySet.iterator();

        assertTrue(iterator.hasNext());

        // copying implicitly iterates an iterator
        Set<Map.Entry<String, String>> copy1 = new HashSet<>(entrySet);
        Set<Map.Entry<String, String>> copy2 = new HashSet<>(entrySet);

        assertEquals(copy2, copy1);
        assertTrue(iterator.hasNext());
    }
}