/** Tests the hash code computation. */
@Test
public void testHashCode() {
final CitationImpl citation = new CitationImpl();
final PropertyAccessor accessor = createPropertyAccessor(citation);
int hashCode = accessor.hashCode(citation);
assertEquals("Empty metadata.", 0, hashCode);
final String ISBN = "Dummy ISBN";
citation.setISBN(ISBN);
hashCode = accessor.hashCode(citation);
assertEquals("Metadata with a single String value.", ISBN.hashCode(), hashCode);
final Set<Object> set = new HashSet<Object>();
assertEquals("By Set.hashCode() contract.", 0, set.hashCode());
assertTrue(set.add(ISBN));
assertEquals("Expected Metadata.hashCode() == Set.hashCode().", set.hashCode(), hashCode);
final InternationalString title = new SimpleInternationalString("Dummy title");
citation.setTitle(title);
hashCode = accessor.hashCode(citation);
assertEquals("Metadata with two values.", ISBN.hashCode() + title.hashCode(), hashCode);
assertTrue(set.add(title));
assertEquals("Expected Metadata.hashCode() == Set.hashCode().", set.hashCode(), hashCode);
assertEquals("CitationsImpl.hashCode() should delegate.", hashCode, citation.hashCode());
final Collection<Object> values = citation.asMap().values();
assertEquals(hashCode, new HashSet<Object>(values).hashCode());
assertTrue(values.containsAll(set));
assertTrue(set.containsAll(values));
}
@Override
public int hashCode() {
int code = 0;
if (parent != null) code = parent.hashCode();
code ^= thisHashCode();
return code;
}