Skip to content
A local arena for codingame multiplayer puzzles
Java Dockerfile
Branch: master
Clone or download
dreignier Merge pull request #26 from fala13/master
Added referee links for UTG, LOCAM and CoK.
Latest commit 73d1161 Oct 10, 2019


cg-brutaltester is a Java local tool to simulate the CodinGame multiplayer IDE. How does it work? Very simple:

java -jar cg-brutaltester.jar -r "java -jar cg-referee-ghost-in-the-cell.jar" -p1 "./myCode.exe" -p2 "php myCode.php" -t 2 -n 100 -l "./logs/"

At the end of the command, you will get something like this:

13:19:47,629 INFO  [com.magusgeek.brutaltester.Main] *** End of games ***
| Results  | Player 1 | Player 2 |
| Player 1 |          | 7,00%    |
| Player 2 | 52,70%   |          |

How to read it: Player 1 won 7.00% of the time against Player 2. Player 2 won 52.70% of the time against Player 1. The total is not 100% because you have some draws.

How to build from sources

  1. Install Java 1.8 (JDK)
  2. Install Maven.
  3. Run in command line <path_to_maven>/mvn package inside root directory of this repo.
  4. ./target/cg-brutaltester-0.0.1-SNAPSHOT.jar — is compiled brutaltester! You can rename it to cg-brutaltester.jar to make command line above work.

Now you should get (or compile from sources) referee for specific game and make it work together with brutaltester as stated above.

Command line arguments:

Referee -r <string> (Mandatory)

This is the command line to start the referee process. The referee must respect the cg-brutaltester protocol. See How do I make my own referee? for more information. In our example, we use a runnable Jar file as the referee.

Player X -pX <string> (Mandatory)

Each -pX argument is the command line to start a player process. You can give a maximum of 4 players. But don't forget the some referees will ignore some players (for example, Ghost in the Cell only uses 2 players). In the example, the first player is a simple executable file and the second player is a php file.

Threads -t <int> (Optional; Default is 1)

The number of threads to spawn for the games. If you give 2, it means that you will have 2 games playing at the same time. It's useless to spawn too many threads. If you have a 4-core CPU, you should not try to spawn more than 3 threads.

Number of games -n <int> (Optional; Default is 1)

The number of games to play. The given example will play 100 games.

Logs directory -l <string> (Optional)

You may need the logs of the file. If you specify a directory, all games will be saved in the given directory. The files contain standard and error outputs of all processes (referee and players).

Swap player positions -s (Optional)

There are some games (such as Tron), where one player has a disadvantage from the beginning on because of an asymmetric map. In this case you can repeat the game on the same map, but with positions changed. For more than two players this will perform a simple rotation and not test all permutations (resulting in 4 matches on the same map for 4 players instead of 24). NOTE: not all referees support this flag, as they have to allow setting a seed.

Initial Seed -i <int> (Optional)

It allows to use the same seeds in different runs. You can't select individual seeds, but only the starting seed for the Random Number Generator. It's useful to have repeteable tests.

Old mode -o (Optional)

Since Botters of the Galaxy and Ultimate Tic Tac Toe, Codingame changed a lot the way of creating a referee. Because of that, all games created before Botters of the Galaxy and Ultimate Tic Tac Toe use the "old way". If you want to use an old referee, you have to use this flag.

Verbose -v

Activate the verbose mode. Spam incoming.

Help -h

Display this help :

usage: -r <referee command line> -p1 <player1 command line> -p2 <player2 command line> -p3 <player3 command line> -p4 <player4 command line> [-v -n <games> -t <thread>]
 -h          Print the help
 -l <arg>    A directory for games logs
 -n <arg>    Number of games to play. Default 1.
 -p1 <arg>   Required. Player 1 command line.
 -p2 <arg>   Required. Player 2 command line.
 -p3 <arg>   Player 3 command line.
 -p4 <arg>   Player 4 command line.
 -r <arg>    Required. Referee command line.
 -s          Swap player positions
 -i <arg>    Initial Seed. For repeteable tests.
 -t <arg>    Number of thread to spawn for the games. Default 1.
 -v          Verbose mode. Spam incoming.

How do I make my own referee?


Since Botters of the Galaxy and Ultimate Tic Tac Toe, CodinGame change a lot the way of creating a referee. Because of that, cg-brutaltester had to adapt.

If you want to use or create a referee for a game created before Botters of the Galaxy or Ultimate Tic Tac Toe, use this wiki page.

Your referee must be runnable with a command line (or you won't be able to give it to cg-brutaltester) and you have to use the standard input and output streams. The referee can output on the error stream for debug purposes or real errors. It will be stored in the log file of the game. cg-brutaltester is a very naive arena, and the referee must tell it how to work.

All steps

As an example, you can check my Ultime Tic Tac Toe brutaltester referee To create your own referee for cg-brutaltester, there's X steps to follow:

  • Fork the referee repository
  • Modify the pom.xml file.
  • Add the CommandLineInterface class in the package com.codingame.gameengine.runner

I'm currently thinking of a way to automate the process. Copy/pasting CommandLineInterface is good enough for now, but this is clearly not the best thing to do.

Incoming features

This is not an official roadmap at all.

  • Generate an html file for the results (with graphics!)
  • Better handling of crashing players' code
  • Handle timeouts
  • Conquer the world

List of compatible referees

If you have a bug or a problem with one of these referees, create an issue of the github project of the referee, not on cg-brutaltester project. This may not be a full list of available referees for cg-brutaltester. If you want to add a referee to this list, just make a pull request.

You can’t perform that action at this time.