Evolutionary Grammar Fuzzing¶

This chapter is work in progress ("beta"). It is incomplete and may change at any time.

In this chapter, we introduce how to implement search-based test generation on grammars, using genetic improvement operators such as mutation and cross-over on derivation trees.

Prerequisites

You should have read the chapter on search-based test generation.
You should have read the chapter on recombining inputs.

import fuzzingbook_utils

import SearchBasedFuzzer
import LangFuzzer

Grammar-Based Mutation¶

General idea: Take a derivation tree and a matching grammar; apply a random mutation.

from Grammars import EXPR_GRAMMAR
from GrammarFuzzer import display_tree
from Parser import EarleyParser

parser = EarleyParser(EXPR_GRAMMAR)
tree, *_ = parser.parse("1 + 2 * 3")
display_tree(tree)

Pick any node in the tree
Produce a new expansion.

We have seen this for LangFuzzer already, right?

How about we factor this out (from the Parser notebook), and have two notebook on mutational (and genetic fuzzing):

LangFuzzer – a chapter on
- Mutating trees (randomly)
- Mutating trees from a given population (the LangFuzz approach)
- Tree recombination (and crossover)
EvoGrammarFuzzer – a chapter on
- Genetic improvement (using coverage only)
- Genetic improvement (using a fitness function from search-based fuzzing)

def mutate_tree(tree, grammar):
    pass

Grammar-Based Crossover¶

Lessons Learned¶

Lesson one
Lesson two
Lesson three

Next Steps¶

Link to subsequent chapters (notebooks) here, as in:

Background¶

Cite relevant works in the literature and put them into context, as in:

The idea of ensuring that each expansion in the grammar is used at least once goes back to Burkhardt [Burkhardt et al, 1967.], to be later rediscovered by Paul Purdom [Purdom et al, 1972.].

Exercises¶

Close the chapter with a few exercises such that people have things to do. To make the solutions hidden (to be revealed by the user), have them start with

markdown
**Solution.**

Your solution can then extend up to the next title (i.e., any markdown cell starting with #).

Running make metadata will automatically add metadata to the cells such that the cells will be hidden by default, and can be uncovered by the user. The button will be introduced above the solution.

Exercise 1: Title¶

Text of the exercise

# Some code that is part of the exercise
pass

Some more text for the exercise

Use the notebook to work on the exercises and see solutions.

Exercise 2: Title¶