jtd-fuzz generates example data from a JSON Typedef schema.
bash
echo '{ "elements": { "type": "string" }}' | jtd-fuzz -n 5
json
["_","/+Z`","8o~5[7A"]
[]
["@(;","*+!YVz"]
["u4sv>Sp","Uc","o`"]
["","G","*ZJsc","","","\"RT,","l>l"]
A note on security: jtd-fuzz does not use a cryptographically-secure
random-number generator. Do not use jtd-fuzz to generate randomness, if that
randomness needs to be cryptographically secure.
To install jtd-fuzz, you have a few options:
This option is recommended if you're on macOS.
bash
brew install jsontypedef/jsontypedef/jtd-fuzz
This option is recommended on non-Mac platforms, or if you're running jtd-fuzz
in some sort of script and you want to make sure that everyone running the
script uses the same version of jtd-fuzz.
bash
docker pull jsontypedef/jtd-tools
If you opt to use the Docker approach, you will need to change all invocations
of jtd-fuzz in this README from:
bash
jtd-fuzz [...]
To:
bash
docker exec -it jsontypedef/jtd-tools /jtd-fuzz [...]
This option is recommended if you already have cargo installed, or if you
would prefer to use a version of jtd-fuzz compiled on your machine:
bash
cargo install jtd-fuzz
To invoke jtd-fuzz, you can either:
jtd-fuzz.jtd-fuzz reads in a single JSON Typedef schema, and will output, by default,
an infinite stream of examples. For example, this will output an infinite
sequence of random JSON data:
bash
echo '{}' | jtd-fuzz
If you'd like to have jtd-fuzz output an exact number of results, use -n:
bash
echo '{}' | jtd-fuzz -n 5
By default, jtd-fuzz will generate different output every time:
bash
echo '{}' | jtd-fuzz -n 1 ; echo '{}' | jtd-fuzz -n 1
json
{"[jD|6W":null}
null
If you'd like to get consistent output from jtd-fuzz, or be able to reproduce
its output, you can use the -s option to provide a seed to its internal
pseudo-random number generator. For the same seed and schema, jtd-fuzz will
output the same data every time:
bash
echo '{}' | cargo run -- -n 1 -s 1815 ; echo '{}' | cargo run -- -n 1 -s 1815
json
{"":null,"8= Rk":0.4883371274545145,";":0.6198663347278088,"Zg":[["O^;BZ",92,null,["9]0MZ_q",null,{}]],null,0.7705810550086981,"xb",false,"i","h"],"m83":115}
{"":null,"8= Rk":0.4883371274545145,";":0.6198663347278088,"Zg":[["O^;BZ",92,null,["9]0MZ_q",null,{}]],null,0.7705810550086981,"xb",false,"i","h"],"m83":115}
The -s option takes an integer between 0 and 2^64 - 1.
The -s option can be useful if you're using jtd-fuzz to do automated testing
against a system. Your automated testing system can pass jtd-fuzz a
randomly-generated seed, and if the automated tester finds a seed that generates
problematic output, it can output the seed it used. That way, developers can
re-use that seed, and try to reproduce the issue locally.
Note that jtd-fuzz is only guaranteed to produce consistent output if you use
the same seed, schema, and version of jtd-fuzz. Different versions on
jtd-fuzz may output different results, even if you give them the same seed and
schema.