### Question:
Serializer { public void writeCommand(Command command) throws IOException { writer.write("@"); writer.write(command.getName()); for (Argument argument : command.getArguments()) { writer.write(" "); if (argument.fromRule().isPresent()) { writeRuleNoStatment(argument.fromRule().get()); } else if (argument.fromPositiveLiteral().isPresent()) { writeLiteral(argument.fromPositiveLiteral().get()); } else { writeTerm(argument.fromTerm().get()); } } writer.write(STATEMENT_END); } Serializer(final Writer writer, final Function<String, String> iriTransformer);  Serializer(final Writer writer);  Serializer(final Writer writer, PrefixDeclarationRegistry prefixDeclarationRegistry); void writeStatement(Statement statement); void writeFact(Fact fact); void writeRule(Rule rule); void writeDataSourceDeclaration(DataSourceDeclaration dataSourceDeclaration); void writeLiteral(Literal literal); void writePositiveLiteral(Predicate predicate, List<Term> arguments); void writeLiteralConjunction(final Conjunction<? extends Literal> literals); void writePredicate(Predicate predicate); void writeTerm(Term term); void writeAbstractConstant(AbstractConstant abstractConstant); void writeDatatypeConstant(DatatypeConstant datatypeConstant); void writeDatatypeConstantNoAbbreviations(DatatypeConstant datatypeConstant); void writeUniversalVariable(UniversalVariable universalVariable); void writeExistentialVariable(ExistentialVariable existentialVariable); void writeNamedNull(NamedNull namedNull); boolean writePrefixDeclarationRegistry(PrefixDeclarationRegistry prefixDeclarationRegistry); void writeLanguageStringConstant(LanguageStringConstant languageStringConstant); void writeCommand(Command command); static String getSerialization(SerializationWriter writeAction); static final String STATEMENT_END; static final Function<String, String> identityIriSerializer; }### Answer:
@Test public void serializeCommand() throws IOException { ArrayList<Argument> arguments = new ArrayList<>(); arguments.add(Argument.term(abstractConstant)); arguments.add(Argument.positiveLiteral(fact)); arguments.add(Argument.rule(rule)); Command command = new Command("command", arguments); serializer.writeCommand(command); assertEquals("@command <http: }