### Question:
CrnConverter implements AttributeConverter<Crn, String> { @Override public String convertToDatabaseColumn(Crn attribute) { return attribute.toString(); }  @Override String convertToDatabaseColumn(Crn attribute); @Override Crn convertToEntityAttribute(String dbData);  }### Answer:
@Test public void testConvertToDbField() { String dbField = underTest.convertToDatabaseColumn(validCrn); assertEquals(validCrn.toString(), dbField); }