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<title>Module proper_target</title>
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<h1>Module proper_target</h1>
<ul class="index"><li><a href="#description">Description</a></li><li><a href="#types">Data Types</a></li><li><a href="#index">Function Index</a></li><li><a href="#functions">Function Details</a></li></ul>This module defines the top-level behaviour for targeted
property-based testing (TPBT).
<p>Copyright © 2017 Andreas Löscher and Kostis Sagonas</p>
<p><b>Version:</b> Sep 22 2018 19:52:28</p>
<p><b>Authors:</b> Andreas Löscher.</p>
<h2><a name="description">Description</a></h2><p>This module defines the top-level behaviour for targeted
property-based testing (TPBT). Using TPBT the input generation
is no longer random, but guided by a search strategy to increase
the probability of finding failing input. For this to work the user
has to specify a search strategy and also needs to extract
utility-values from the system under test that the search strategy
then tries to maximize.</p>
<p>To use TPBT the test specification macros <code>?FORALL_TARGETED`, `?EXISTS</code>,
and <code>?NOT_EXISTS</code> are used. The typical structure for a targeted
property looks as follows:</p>
<pre> prop_target() -> % Try to check that
?EXISTS(Input, Params, % some input exists
begin % that fullfills the property.
UV = SUT:run(Input), % Do so by running SUT with Input
?MAXIMIZE(UV), % and maximize its Utility Value
UV < Threshold % up to some Threshold.
end)).</pre>
<h3><a name="Macros">Macros</a></h3>
<dl>
<dt><code>?MAXIMIZE(UV)</code></dt>
<dd>This tells the search strategy to maximize the value <code>UV</code>.</dd>
<dt><code>?MINIMIZE(UV)</code></dt>
<dd>equivalent to <code>?MAXIMIZE(-UV)</code></dd>
<dt><code>?USERNF(Gen, Nf)</code></dt>
<dd>This uses the neighborhood function <code>Nf</code> instead of PropEr's
constructed neighborhood function for this generator. The neighborhood
function <code>Fun</code> should be of type <code>proper_gen_next:nf()</code></dd>
<dt><code>?USERMATCHER(Gen, Matcher)</code></dt>
<dd>This overwrites the structural matching of PropEr with the user provided
<code>Matcher</code> function. the matcher should be of type <code>proper_gen_next:matcher()</code></dd>
</dl>
<h2><a name="types">Data Types</a></h2>
<h3 class="typedecl"><a name="type-fitness">fitness()</a></h3>
<p><pre>fitness() = number()</pre></p>
<h3 class="typedecl"><a name="type-fitness_func">fitness_func()</a></h3>
<p><pre>fitness_func() =
fun((<a href="#type-target_state">target_state()</a>, <a href="#type-fitness">fitness()</a>) -> <a href="#type-target_state">target_state()</a>) | none</pre></p>
<h3 class="typedecl"><a name="type-key">key()</a></h3>
<p><pre>key() = nonempty_string() | reference()</pre></p>
<h3 class="typedecl"><a name="type-next_func">next_func()</a></h3>
<p><pre>next_func() = fun((<a href="#type-target_state">target_state()</a>) -> {<a href="#type-target_state">target_state()</a>, any()})</pre></p>
<h3 class="typedecl"><a name="type-strategy">strategy()</a></h3>
<p><pre>strategy() = module()</pre></p>
<p> -----------------------------------------------------------------------------
proper_target callback functions for defining strategies
----------------------------------------------------------------------------</p>
<h3 class="typedecl"><a name="type-target">target()</a></h3>
<p><pre>target() = {<a href="#type-target_state">target_state()</a>, <a href="#type-next_func">next_func()</a>, <a href="#type-fitness_func">fitness_func()</a>}</pre></p>
<h3 class="typedecl"><a name="type-target_state">target_state()</a></h3>
<p><pre>target_state() = term()</pre></p>
<h3 class="typedecl"><a name="type-tmap">tmap()</a></h3>
<p><pre>tmap() = #{atom() => term()}</pre></p>
<h2><a name="index">Function Index</a></h2>
<table width="100%" border="1" cellspacing="0" cellpadding="2" summary="function index"><tr><td valign="top"><a href="#init_strategy-1">init_strategy/1</a></td><td></td></tr>
<tr><td valign="top"><a href="#strategy-0">strategy/0</a></td><td></td></tr>
</table>
<h2><a name="functions">Function Details</a></h2>
<h3 class="function"><a name="init_strategy-1">init_strategy/1</a></h3>
<div class="spec">
<p><pre>init_strategy(Strat :: <a href="#type-strategy">strategy()</a>) -> ok</pre></p>
</div>
<h3 class="function"><a name="strategy-0">strategy/0</a></h3>
<div class="spec">
<p><pre>strategy() -> <a href="#type-strategy">strategy()</a></pre></p>
</div>
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