esfuzz/README.md

JS fuzzer for generative testing of parsers that implement the SpiderMonkey Reflect.parse API

# esfuzz

Fuzzer for generative testing of ECMAScript parsers, especially those that
implement the [SpiderMonkey `Reflect.parse` API](https://developer.mozilla.org/en-US/docs/SpiderMonkey/Parser_API).

## Install

    npm install -g esfuzz

## Usage

### CLI

    $ esfuzz --help


      Usage: esfuzz OPT*

      -n, --iterations NUM  use at most NUM programs; default: unlimited
      -d, --max-depth NUM   create ASTs with a height no greater than NUM; default: 8
      --acorn               enable marijnh/acorn parser; default: on
      --es6                 allow ECMAScript 6 features in generated programs
      --esprima             enable ariya/esprima parser; default: on
      --help                display this help message and exit
      --reflect             enable Reflect.parse parser; default: on if it exists
      --reflectjs           enable zaach/reflect.js parser
      --uglifyjs            enable limited support for mishoo/UglifyJS2
      --version             display the version number and exit
      --zeparser            enable limited support for qfox/ZeParser

### Module Interface

#### `generate(options)` -> `SpiderMonkey_AST`

Generate a random SpiderMonkey AST that represents a valid ECMAScript program.
Available options:

  * `maxDepth`: create ASTs with a height no greater than this value

#### `render(programAST, format)` -> `String` (JS program)

Render a SpiderMonkey AST as an ECMAScript program. If the `format` argument is
omitted, a random format will be used. Otherwise, the given object must be in
the format of escodegen's `format` option.

#### `fuzz(programAST, parsers)` -> `void`

Takes a SpiderMonkey AST and a list of objects that have a `parse` method that
obeys the SpiderMonkey Reflect.parse API. This function will generate concrete
syntax and run it through each parser. If any of the parsers fail to parse the
program, an error will be thrown.

#### `fuzzAndRoundtrip(programAST, parsers)` -> `void`

Identical to `fuzz`, except additionally compares the outputs of each parser to
the generated program. If any of the parsers fail to parse the program or fail
to generate an AST equivalent to the given one, an error will be thrown.