Whisker is an automated testing framework for Scratch projects.
Block-based programming environments like Scratch foster engagement with computer programming and are used by millions of young learners. Scratch allows learners to quickly create entertaining programs and games, while eliminating syntactical program errors that could interfere with progress.
However, functional programming errors may still lead to incorrect programs, and learners and their teachers need to identify and understand these errors. This is currently an entirely manual process.
Whisker provides automated and property-based testing functionality for Scratch programs.
Whisker requires Node.js v18.18.0 and is built using the yarn (classic) package manager.
After cloning the repository, install all dependencies using:
yarn installNow you can build the application using:
yarn buildAfter building Whisker, simply open 'whisker-web/dist/index.html' in your browser (e.g. Firefox)
firefox whisker-web/dist/index.htmlThe Servant is a wrapper around the web client, allowing to run tests automatically in a headless environment (via chrome-headless / puppeteer). It is called the Servant as in "Cats don't have owners they have servants".
To use Whisker on the command line, you can use the Servant node frontend as follows:
node servant run -s <Scratch project file> -t <test file>An overview of options is provided using node servant help:
Usage: node servant [options] [command]
A Testing Utility for Scratch 3.0
Options:
-h, --help display help for command
-V, --version output the version number
Commands:
open [options] open the Whisker web interface
dynamic [options] dynamic test suites using Neuroevolution
generate [options] generate Whisker test suites
help [options] [command] display help for command
model [options] test with model
run [options] run Whisker tests
witness [options] generate and replay error witnessesTo show further help, additionally pass the name of the command you are interested in, e.g.,
the run command: node servant help run.
Usage: node servant run [options]
run Whisker tests
Options:
-a, --acceleration <Integer> acceleration factor (default: 1)
-d, --headless run headless ("d" like in "decapitated") (default: false)
-e, --mutants-download-path <Path> where generated mutants should be saved
-h, --help display help for command
-j, --number-of-jobs <Integer> number of jobs (Chromium tabs) for test execution (default: 1)
-k, --console-forwarded forward browser console output
-l, --live-log print new log output regularly
-m, --mutators <String...> mutation operators to apply
-o, --live-output-coverage print new coverage output regularly
-s, --scratch-path <Path> path to file (".sb3") or folder with scratch application(s)
-t, --test-path <Path> path to Whisker tests to run (".js")
-v, --csv-file <Path> create CSV file with results
-z, --seed <String> custom seed for Scratch-VM
-et, --executionTrace whether and execution trace should be recorded and downloaded (default: false)
-rec, --state-action-recorder record the program execution as a json file when running with the `open` commandTo run tests in accelerated mode, provide an acceleration factor using the option -a. We recommend using an
acceleration factor of at most 10, as very low execution times may lead to non-deterministic program behaviour.
For example, the following command runs tests with a 10-fold speedup and two parallel executions in a headless chrome instance:
node servant run -s project.sb3 -t tests.js -a 10 -d -j 2Alternatively, you can build and run Whisker in headless mode using docker. This can be beneficial if you want to conduct large-scale experiments on a computing cluster. To this, create a Docker image for Whisker, for example using the command
docker build -t whisker .Now, you can run the dockerized version of Whisker via
docker run whisker <additional arguments>The main entry point to the container is the wrapper script whisker-docker.sh, which calls Whisker's servant in
headless mode (using the flags -d, -k and -l, among others.) Any <additional arguments> given by the user will
be forwarded by the script to the servant.
In case you want to copy the artefacts created by Whisker (including redirection of stdout and stderr) to files in a writable bind mount, you can achieve this for example as follows:
docker run -v "/on/the/host:/inside/the/container" whisker /inside/the/container -- <Whikser arguments>This will mount the directory /on/the/host as /inside/the/container, instruct Whisker to copy its output (such as
generated test files and log messages) to files in /inside/the/container, and make them accessible to you in the
directory /on/the/host.
Details on writing Whisker tests in JavaScript can be found here.
The web interface provides the possibility to automatically generate tests. In the web interface, choose an appropriate
search configuration (examples can be found in the config directory), and click Test Generation. Warning: This may
take a while! Once the search has completed, the generated tests are loaded into the editor window.
If you run test generation with Servant (command line option -g), at the end of the search a file called tests.js
is created in the current directory which contains the tests. These can now be loaded into Whisker.
Whisker is developed at the Chair of Software Engineering II of the University of Passau.
Contributors:
Adina Deiner
Patric Feldmeier
Christoph Frädrich
Gordon Fraser
Sophia Geserer
Katharina Götz
Eva Gründinger
Nina Körber
Marvin Kreis
Sebastian Schweikl
Andreas Stahlbauer
Emma Wang
Phil Werli
Nik Zantner
Whisker is supported by the project FR 2955/3-1 funded by the "Deutsche Forschungsgemeinschaft".
@inproceedings{DBLP:conf/sigsoft/StahlbauerKF19,
author = {Andreas Stahlbauer and
Marvin Kreis and
Gordon Fraser},
title = {Testing scratch programs automatically},
booktitle = {{ESEC/SIGSOFT} {FSE}},
pages = {165--175},
publisher = {{ACM}},
year = {2019}
}
@inproceedings{DBLP:conf/ssbse/DeinerFFGZ20,
author = {Adina Deiner and Christoph Fr{\"{a}}drich and
Gordon Fraser and Sophia Geserer and
Niklas Zantner},
title = {Search-Based Testing for Scratch Programs},
booktitle = {12th International Symposium on Search-Based Software Engineering},
series = {Lecture Notes in Computer Science},
volume = {12420},
pages = {58--72},
publisher = {Springer},
year = {2020},
}
@InProceedings{gotz2022model,
title = {Model-based Testing of Scratch Programs},
author = {G{\"o}tz, Katharina and Feldmeier, Patric and Fraser, Gordon},
booktitle = {Proceedings of the International Conference on Software Testing, Verification and Validation (ICST'22)},
pages = {411--421},
year = {2022},
publsiher = {IEEE},
doi = {10.1109/ICST53961.2022.00047}
}
@misc{deiner2022automated,
title = {Automated Test Generation for Scratch Programs},
author = {Adina Deiner and Patric Feldmeier and Gordon Fraser and Sebastian Schweikl and Wengran Wang},
year = {2022},
eprint = {2202.06274},
archivePrefix = {arXiv},
primaryClass = {cs.SE}
}
@InProceedings{feldmeier2022neuroevolution,
author = {Feldmeier, Patric and Fraser, Gordon},
booktitle = {Proceedings of the International Conference on Automated Software Engineering (ASE'22)},
publisher = {ACM},
title = {Neuroevolution-Based Generation of Tests and Oracles for Games},
year = {2023},
doi = {10.1145/3551349.3556939},
pages = {1--13}
}
@article{feldmeier2023learning,
title = {Learning by Viewing: Generating Test Inputs for Games by Integrating Human Gameplay Traces in Neuroevolution},
author = {Feldmeier, Patric and Fraser, Gordon},
journal = {arXiv preprint arXiv:2304.06413},
year = {2023},
doi = {10.48550/arXiv.2304.06413}
}
@inproceedings{nuzzlebug24,
author = {Adina Deiner and Gordon Fraser},
title = {NuzzleBug: Debugging Block-Based Programs in Scratch },
booktitle = {ACM/IEEE International Conference on Software Engineering (ICSE)},
publisher = {{IEEE}},
year = {2024}
}