Triq (pronounced "Trick Check") is a free alternative to QuviQ
eqc. Triq's API is modelled closely after
eqc, so I recommend their tutorials and slides for an introduction
to QuickCheck. Notice that QuviQ eqc has many features not found in
triq, but it is open source licensed under the Apache license. For
instance, eqc has features for reporting, management, probably a
much better shrinking mechanism, and cool C integration, and
professional support.
To use triq, you download the latest version from
here, and untar it
into your erlang lib directory (typically
/usr/local/lib/erlang/lib):
prompt$ cd /usr/local/lib/erlang/lib propmt$ tar xvzf triq-0.1.0.tgz ...
And you're all set. Next, to use triq, include the header file:
-include_lib("triq/include/triq.hrl").
And you're ready to write property tests. An example property could be:
prop_append() ->
?FORALL({Xs,Ys},{list(int()),list(int())},
lists:reverse(Xs++Ys)
==
lists:reverse(Ys) ++ lists:reverse(Xs)).
To test this property, run triq:check/1, thus:
1> triq:check(prop_append()). ...................................................................... .............................. Ran 100 tests true 2>
If the test fails, it will try to shrink the result; here is an example:
prop_delete() ->
?FORALL(L,list(int()),
?IMPLIES(L /= [],
?FORALL(I,elements(L),
?WHENFAIL(io:format("L=~p, I=~p~n", [L,I]),
not lists:member(I,lists:delete(I,L)))))).
Which runs like this:
1> triq:check(triq_tests:prop_delete()).
x....Failed!
L=[4,5,5], I=5
Failed after 5 tests with false
Simplified:
L = [0,0]
I = 0
false
2>
You can get the values used for the failing test with counterexample,
and reuse the same test values with check/2:
3> A = triq:counterexample(triq_tests:xprop_delete()). x.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxFailed! L=[3,2,1,1,1], I=1 Failed after 101 tests with false Simplified: L = [0,0] I = 0 [[0,0],0] 4> A. [[0,0],0] 5> triq:check(triq_tests:xprop_delete(), A). Failed! L=[0,0], I=0 Failed after 1 tests with false Simplified: L = [0,0] I = 0 false 6>
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.
1> mymodule:check().
A handy addition that I use it to also add an eunit test, which tests it:
property_test() -> true == check().
Which can then automatically be run using your favourite enuit runner.
Good luck!