### Question:
NamedFieldsMapping implements FieldsMapping { @Override public int fieldMetaIndex( int index ) { if ( index >= size() || index < 0 ) { return FIELD_DOES_NOT_EXIST; } return actualToMetaFieldMapping[index]; } NamedFieldsMapping( int[] actualToMetaFieldMapping ); @Override int fieldMetaIndex( int index ); @Override int size(); static NamedFieldsMapping mapping( String[] actualFieldNames, String[] metaFieldNames );  }### Answer:
@Test public void fieldMetaIndex() { assertEquals( 3, fieldsMapping.fieldMetaIndex( 0 ) ); }
@Test public void fieldMetaIndexWithUnexistingField() { assertEquals( FieldsMapping.FIELD_DOES_NOT_EXIST, fieldsMapping.fieldMetaIndex( 4 ) ); }