[erlang-questions] [ANN] Triq community fork

[Tuncer Ayaz]

We are pleased to announce the community fork of Triq.

Triq (Term Reductive Invariant Questant) is an Apache licensed QuickCheck
library for Erlang. It is a continuation and community fork of
https://github.com/krestenkrab/triq. This fork is in *no way* affiliated
with or a product of Trifork.

| Homepage | https://triq.gitlab.io
| Hex.pm   | https://hex.pm/packages/triq
| Team     | https://gitlab.com/triq/triq/project_members

If you use Triq and/or want to contribute, we do welcome new team members.
It's a community fork after all.

* Writing QuickCheck properties with Triq

To write properties with Triq, you just include triq.hrl:

-include_lib("triq/include/triq.hrl").

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 your
module into a regular EUnit test suite.

If you use erlang.mk, you will typically want to use the built-in Triq
plugin (https://erlang.mk/guide/triq.html) to check properties. Otherwise,
we highly recommend letting Triq generate EUnit tests, thus arriving at a
demo module like this:

-module(triq_demo).
-include_lib("triq/include/triq.hrl").
-triq(eunit).
prop_append() ->
    ?FORALL({Xs,Ys},{list(int()),list(int())},
            lists:reverse(Xs++Ys)
            ==
            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 "triq_demo.app"
  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

Triq is available via Hex.pm and its git repository. If your build tool
supports it, we suggest to use the Hex.pm package.

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