MessageFormatV4 implements MessageFormat { @Override public Writer newWriter( PackOutput output ) { return new MessageWriterV4( output ); }  @Override Writer newWriter( PackOutput output ); @Override Reader newReader( PackInput input );  }
@Test void shouldCreateCorrectWriter() { MessageFormat.Writer writer = format.newWriter( mock( PackOutput.class ) ); assertThat( writer, instanceOf( MessageWriterV4.class ) ); }