Grammarinator

ANTLRv4 grammar-based test generator

Grammarinator is a random test generator / fuzzer that creates test cases according to an input ANTLR v4 grammar. The motivation behind this grammar-based approach is to leverage the large variety of publicly available ANTLR v4 grammars.

The trophy page of the found issues is available from the wiki.

Requirements

Python >= 3.7
Java SE >= 11 JRE or JDK (the latter is optional)

Install

To use Grammarinator in another project, it can be added to setup.cfg as an install requirement (if using setuptools with declarative config):

[options]
install_requires =
    grammarinator

To install Grammarinator manually, e.g., into a virtual environment, use pip:

pip install grammarinator

The above approaches install the latest release of Grammarinator from PyPI. Alternatively, for the development version, clone the project and perform a local install:

pip install .

Usage

As a first step, Grammarinator takes an ANTLR v4 grammar and creates a test generator script in Python3. Grammarinator supports a subset of the features of the ANTLR grammar which is introduced in the Grammar overview section of the documentation. The produced generator can be subclassed later to customize it further if needed.

Basic command-line syntax of test generator creation:

grammarinator-process <grammar-file(s)> -o <output-directory> --no-actions

After having generated and optionally customized a fuzzer, it can be executed by the grammarinator-generate script (or by manually instantiating it in a custom-written driver, of course).

Basic command-line syntax of grammarinator-generate:

grammarinator-generate <generator> -r <start-rule> -d <max-depth> \
  -o <output-pattern> -n <number-of-tests> \
  -t <transformer1> -t <transformer2>

Beside generating test cases from scratch based on the ANTLR grammar, Grammarinator is also able to recombine existing inputs or mutate only a small portion of them. To use these additional generation approaches, a population of selected test cases has to be prepared. The preparation happens with the grammarinator-parse tool, which processes the input files with an ANTLR grammar (possibly with the same one as the generator grammar) and builds grammarinator tree representations from them (with .grt extension). Having a population of such .grt files, grammarinator-generate can make use of them with the --population cli option. If the --population option is set, then Grammarinator will choose a strategy (generation, mutation, or recombination) randomly at the creation of every new test case. If any of the strategies is unwanted, they can be disabled with the --no-generate, --no-mutate or --no-recombine options.

Basic command line syntax of grammarinator-parse:

grammarinator-parse <grammar-file(s)> -r <start-rule> \
  -i <input_file(s)> -o <output-directory>

Working Example

The repository contains a minimal example to generate HTML files. To give it a try, run the processor first:

grammarinator-process examples/grammars/HTMLLexer.g4 examples/grammars/HTMLParser.g4 \
  -o examples/fuzzer/

Then, use the generator to produce test cases:

grammarinator-generate HTMLCustomGenerator.HTMLCustomGenerator -r htmlDocument -d 20 \
  -o examples/tests/test_%d.html -n 100 \
  -s HTMLGenerator.html_space_serializer \
  --sys-path examples/fuzzer/

Compatibility

Grammarinator was tested on:

Linux (Ubuntu 16.04 / 18.04 / 20.04)
OS X / macOS (10.12 / 10.13 / 10.14 / 10.15 / 11)
Windows (Server 2012 R2 / Server version 1809 / Windows 10)

Citations

Background on Grammarinator is published in:

Renata Hodovan, Akos Kiss, and Tibor Gyimothy. Grammarinator: A Grammar-Based Open Source Fuzzer. In Proceedings of the 9th ACM SIGSOFT International Workshop on Automating Test Case Design, Selection, and Evaluation (A-TEST 2018), pages 45-48, Lake Buena Vista, Florida, USA, November 2018. ACM. https://doi.org/10.1145/3278186.3278193

Copyright and Licensing

Licensed under the BSD 3-Clause License.

renatahodovan / grammarinator