Provided by: libtest-lectrotest-perl_0.5001-3_all bug


       Test::LectroTest::Tutorial - How to use LectroTest to test your software


       version 0.5001


       LectroTest is an automated, specification-based testing system.  To use it, declare
       properties that specify the expected behavior of your software.  Then invoke LectroTest to
       test whether those properties hold.

       LectroTest does this by running repeated random trials against your software.  If
       LectroTest finds that a property doesn't hold, it emits the counterexample that "broke"
       your software.  You can then plug the counterexample into your software to debug the
       problem.  (It's also a good idea to add the counterexample to your list of regression


       Think of your software's behavior as a haystack that you're searching for needles.  Each
       error is a needle.  You want to find the needles and remove of them.  LectroTest will
       search the haystack for you -- it's nice that way -- but first you must tell it about the
       shape of the haystack and how to recognize a needle when it sees one.

   The Haystack
       The shape of the haystack is defined by a set of "generator bindings," in which variables
       are bound to the output of value generators:

         x <- Int, c <- Char( charset=>"A-Z" )

       The above can be read, "For all integers x and all characters c in the range A through Z."
       The idea is that each unique instance of the pair (x, c) specifies a point in the haystack
       that we can search for needles.

   The Needle Recognizer
       The "needle recognizer" is defined by a snippet of code that uses the bound variables to
       inspect a given point in the haystack.  It returns a "thumbs up" (true) if the point is
       free of needles or a "thumbs down" (false) if it finds a needle:

         the_thing_we_are_testing($x, $c) >= 0;

       The above asserts for each point in the haystack that the output of the function
       "the_thing_we_are_testing" must be non-negative.

   Put them together to make a Property
       The generator bindings and needle recognizer are combined to make a property:

         Property {
           ##[ x <- Int, c <- Char( charset=>"A-Z" ) ]##
           the_thing_we_are_testing($x, $c) >= 0;
         }, name => "the_thing_we_are_testing(...) is non-negative";

       You'll note that we also added a meaningful name.  Although not strictly required, it's an
       excellent practice that makes life easier.  (You'll also note that we placed the generator
       bindings inside of the magic delimiters "##[ ]##".  This tells Perl that our bindings are
       bindings and not regular Perl code.)

       We can read the above property like so: "For all integers x and all characters c in the
       range A through Z, we assert that "the_thing_we_are_testing" is non-negative."

   Testing whether your Properties hold
       After you define properties for your software, just add them to a small Perl program that
       uses the Test::LectroTest module:

         # MyProperties.l.t

         use MyModule;  # provides the_thing_we_are_testing
         use Test::LectroTest;

         Property {
           ##[ x <- Int, c <- Char( charset=>"A-Z" ) ]##
           the_thing_we_are_testing($x, $c) >= 0;
         }, name => "the_thing_we_are_testing(...) is non-negative";

       Then you can test your properties simply by running the program:

         $ perl MyProperties.l.t

       If your properties check out, you'll see something like this:

         ok 1 - 'the_thing_we_are_testing(...) is non-negative' (1000 attempts)

       If something goes wrong, however, LectroTest will tell you where it happened:

         not ok 1 - 'the_thing_we_are_testing(...) is non-negative' \
           falsified in 23 attempts
         # Counterexample:
         # $x = 4
         # $c = "R"

       What this says is that at the point (x=4, c="R") in the haystack, there is a needle (i.e.,
       your property doesn't hold).  With this information, you can examine your code to
       determine the cause of the error.


       Now that we have big-picture understanding of "LectroTesting," let's try a few examples

       [TODO: write the step-by-step tutorial examples.  For now, take a look at the slides from
       my LectroTest talk for two such examples.  The slides are available at the LectroTest


       Test::LectroTest gives a quick overview of automatic, specification-based testing with

       Test::LectroTest::Property explains in detail what you can put inside of your property

       Test::LectroTest::Generator describes the many generators and generator combinators that
       you can use to define the shapes of the haystacks you encounter during your testing

       Test::LectroTest::TestRunner describes the objects that check your properties and tells
       you how to turn their control knobs.  You'll want to look here if you're interested in
       customizing the testing procedure.


       Tom Moertel (


       The LectroTest project was inspired by Haskell's QuickCheck module by Koen Claessen and
       John Hughes:


       Copyright (c) 2004-13 by Thomas G Moertel.  All rights reserved.

       This program is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.