Triq QuickCheck for Erlang


Triq (Term Reductive Invariant Questant) is an Apache licensed QuickCheck library for Erlang. It is a continuation and community fork of Trifork QuickCheck. This fork is in no way affiliated with, or a product of, Trifork.


By and large, the Triq API is modeled closely after QuviQ eqc, except you want to replace any occurrence of eqc with triq. The main supporting module is called triq_dom, corresponding to eqc's eqc_gen.

Writing QuickCheck properties with Triq

To write properties with triq, include the triq.hrl header file:


Modules compiled with the triq.hrl header auto-export all functions named prop_*, and have a function added called check/0 which runs triq:check/1 on all the properties in the module. Further, adding the attribute -triq(eunit) will generate EUnit tests for all properties, turning the module into a regular EUnit test suite.

If you use, you will typically want to use the built-in Triq plugin to check properties. Otherwise we highly recommend letting Triq generate EUnit tests, thus arriving at a demo module like this:

prop_append() ->
            lists:reverse(Ys) ++ lists:reverse(Xs)).

Now, all you have to do is run rebar3 eunit:

$ rebar3 eunit -v
===> Verifying dependencies...
===> Compiling triq_demo
===> Performing EUnit tests...
======================== EUnit ========================
file ""
  application 'triq_demo'
    triq_demo:5: append_test_ (module 'triq_demo')...[0.262 s] ok
    [done in 0.269 s]
  [done in 0.274 s]
  Test passed.

If you use -triq({eunit, [{runs, N}]}), then Triq will do N runs for each property in the module, which is equivalent to calling triq:check(Module, N). This can be useful to make Triq try more (or less) cases than the default.

For advanced features, please consult the API docs.

Obtaining Triq

Installation via package manager

To use triq, you can add it as a project dependency and let your package manager of choice handle it:

rebar.config {deps, [triq]} DEPS = triq
mix.exs {:triq, "~> 1.*"}

Installation from source into $ERL_LIBS

If you want to make triq available globally, you can install it from source into your Erlang installation by adding it in one of your $ERL_LIBS paths. So, it's either somewhere like /usr/lib/erlang/lib or $HOME/.erl.

You can either download a tagged release and extract that or clone the git repo in the target directory. Once that's done, cd into the directory and run make.

Now, if you start erl, you should be able to call functions from the triq module.

$ erl
1> code:which(triq).

API Documentation

Generated edoc is available here. The interesting modules are triq and triq_dom.