tree-splicer

tree-splicer is a simple grammar-based test case generator. It parses a number of input files using tree-sitter grammars, and produces new files formed by splicing together their ASTs.

tree-splicer generates test cases in the tree-crasher fuzzer and in icemaker, though it can also be used as a standalone tool.

tree-sitter grammars are resistant to syntax errors. Therefore, tree-splicer can even mutate syntactically-invalid inputs! You can also use tree-splicer with an incomplete grammar.

Example

Given this simple Rust program:

use std::env;

fn even(x: usize) -> bool {
    if x % 2 == 0 {
        return true;
    } else {
        return false;
    }
}

fn main() -> () {
    let argc = env::args().len();
    println!("Hello, world!");
    if even(argc) {
        println!("Even!");
    } else {
        println!("Odd!");
    }
    return ();
}

Here are a few candidates created by tree-splicer-rust:

use even::env;

fn even() -> bool {
    if even(argc) {
        println!("Even!");
    } else {
        println!("Odd!");
    }
}

fn std() -> () {
    return true;
}

use args::env;

fn argc(main: usize) -> bool {
    return true;
}

fn even(x: usize) -> bool {
    if x % 2 == 0 {
        return true;
    } else {
        return false;
    }
}

use std::env;

fn x(x: usize) -> bool {
    return true;
}

fn x(x: usize) -> () {
    return false;
}

Supported languages

Languages are easy to add, see PR #3 for an example.

• JavaScript
• Rust
• TypeScript

Bugs found

rustc

#109066 #109071 #109072 #109078 #109079 #109090 #109129 #109141 #109143 #109144 #109146 #109147 #109148 #109152 #109178 #109188 #109191 #109204 #109232 #109239 #109296 #109297 #109298 #109299 #109300 #109304 #109305

rustfmt

#5716

Installation

From a release

Statically-linked Linux binaries are available on the releases page.

From crates.io

You can build a released version from crates.io. You'll need the Rust compiler and the Cargo build tool. rustup makes it very easy to obtain these. Then, to install the generator for the language <LANG>, run:

cargo install tree-splicer-<LANG>

This will install binaries in ~/.cargo/bin by default.

Build

To build from source, you'll need the Rust compiler and the Cargo build tool. rustup makes it very easy to obtain these. Then, get the source:

git clone https://github.com/langston-barrett/tree-splicer
cd tree-splicer

Finally, build everything:

cargo build --release

You can find binaries in target/release. Run tests with cargo test.