### Question:
ServerBootstrapper implements Bootstrapper { public static int start( Bootstrapper boot, String... argv ) { ServerCommandLineArgs args = ServerCommandLineArgs.parse( argv ); if ( args.version() ) { System.out.println( "neo4j " + neo4jVersion() ); return 0; } if ( args.homeDir() == null ) { throw new ServerStartupException( "Argument --home-dir is required and was not provided." ); } return boot.start( args.homeDir(), args.configFile(), args.configOverrides() ); }  static int start( Bootstrapper boot, String... argv ); @Override final int start( File homeDir, Optional<File> configFile, Map<String, String> configOverrides ); @Override int stop(); boolean isRunning(); NeoServer getServer(); Log getLog(); static final int OK; }### Answer:
@Test public void shouldNotThrowNullPointerExceptionIfConfigurationValidationFails() throws Exception { ServerBootstrapper serverBootstrapper = new ServerBootstrapper() { @Override protected GraphFactory createGraphFactory( Config config ) { return new CommunityGraphFactory(); } @Override protected NeoServer createNeoServer( GraphFactory graphFactory, Config config, GraphDatabaseDependencies dependencies ) { return mock( NeoServer.class ); } }; File dir = Files.createTempDirectory( "test-server-bootstrapper" ).toFile(); dir.deleteOnExit(); serverBootstrapper.start( dir, Optional.empty(), MapUtil.stringMap( database_path.name(), homeDir.absolutePath().getAbsolutePath() ) ); assertThat( suppress.getOutputVoice().lines(), not( empty() ) ); }