1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Custom predicate support</title> 5<link rel="stylesheet" href="../../boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../index.html" title="Boost.Test"> 8<link rel="up" href="../testing_tools.html" title="Writing unit tests"> 9<link rel="prev" href="expected_failures.html" title="Expected failures specification"> 10<link rel="next" href="output_stream_testing.html" title="Output streams testing tool"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="expected_failures.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../testing_tools.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="output_stream_testing.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="boost_test.testing_tools.custom_predicates"></a><a class="link" href="custom_predicates.html" title="Custom predicate support">Custom predicate 28 support</a> 29</h3></div></div></div> 30<p> 31 Even though supplied testing tools cover wide range of possible checks and 32 provide detailed report on cause of error in some cases you may want to implement 33 and use custom predicate that perform complex check and produce intelligent 34 report on failure. To satisfy this need testing tools implement custom predicate 35 support. There two layers of custom predicate support implemented by testing 36 tools toolbox: with and without custom error message generation. 37 </p> 38<p> 39 The first layer is supported by <a class="link" href="../utf_reference/testing_tool_ref/assertion_boost_level_predicate.html" title="BOOST_<level>_PREDICATE"><code class="computeroutput"><span class="identifier">BOOST_</span><span class="special"><</span><span class="identifier">level</span><span class="special">></span><span class="identifier">_PREDICATE</span></code></a> family of testing tools. 40 You can use it to check any custom predicate that reports the result as boolean 41 value. The values of the predicate arguments are reported by the tool automatically 42 in case of failure. 43 </p> 44<h6> 45<a name="boost_test.testing_tools.custom_predicates.h0"></a> 46 <span class="phrase"><a name="boost_test.testing_tools.custom_predicates.example_descr"></a></span><a class="link" href="custom_predicates.html#boost_test.testing_tools.custom_predicates.example_descr">Example: 47 Custom predicate support using <code class="computeroutput"><span class="identifier">BOOST_</span><span class="special"><</span><span class="identifier">level</span><span class="special">></span><span class="identifier">_PREDICATE</span></code></a> 48 </h6> 49<div class="informaltable"><table class="table"> 50<colgroup><col></colgroup> 51<thead><tr><th> 52 <p> 53 Code 54 </p> 55 </th></tr></thead> 56<tbody><tr><td> 57<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="preprocessor">#define</span> <span class="identifier">BOOST_TEST_MODULE</span> <span class="identifier">example</span> 58<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">test</span><span class="special">/</span><span class="identifier">included</span><span class="special">/</span><span class="identifier">unit_test</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 59 60<span class="keyword">bool</span> <span class="identifier">is_even</span><span class="special">(</span> <span class="keyword">int</span> <span class="identifier">i</span> <span class="special">)</span> 61<span class="special">{</span> 62 <span class="keyword">return</span> <span class="identifier">i</span><span class="special">%</span><span class="number">2</span> <span class="special">==</span> <span class="number">0</span><span class="special">;</span> 63<span class="special">}</span> 64 65<span class="identifier">BOOST_AUTO_TEST_CASE</span><span class="special">(</span> <span class="identifier">test_is_even</span> <span class="special">)</span> 66<span class="special">{</span> 67 <span class="identifier">BOOST_CHECK_PREDICATE</span><span class="special">(</span> <span class="identifier">is_even</span><span class="special">,</span> <span class="special">(</span><span class="number">14</span><span class="special">)</span> <span class="special">);</span> 68 69 <span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">17</span><span class="special">;</span> 70 <span class="identifier">BOOST_CHECK_PREDICATE</span><span class="special">(</span> <span class="identifier">is_even</span><span class="special">,</span> <span class="special">(</span><span class="identifier">i</span><span class="special">)</span> <span class="special">);</span> 71<span class="special">}</span> 72</pre> 73 </td></tr></tbody> 74</table></div> 75<div class="informaltable"><table class="table"> 76<colgroup><col></colgroup> 77<thead><tr><th> 78 <p> 79 Output 80 </p> 81 </th></tr></thead> 82<tbody><tr><td> 83<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="special">></span> <span class="identifier">example</span> 84<span class="identifier">Running</span> <span class="number">1</span> <span class="identifier">test</span> <span class="keyword">case</span><span class="special">...</span> 85<span class="identifier">test</span><span class="special">.</span><span class="identifier">cpp</span><span class="special">(</span><span class="number">13</span><span class="special">):</span> <span class="identifier">error</span> <span class="identifier">in</span> <span class="string">"test_is_even"</span><span class="special">:</span> <span class="identifier">check</span> <span class="identifier">is_even</span><span class="special">(</span> <span class="identifier">i</span> <span class="special">)</span> <span class="identifier">has</span> <span class="identifier">failed</span> <span class="keyword">for</span> <span class="special">(</span> <span class="number">17</span> <span class="special">)</span> 86 87<span class="special">***</span> <span class="number">1</span> <span class="identifier">failures</span> <span class="identifier">is</span> <span class="identifier">detected</span> <span class="identifier">in</span> <span class="identifier">test</span> <span class="identifier">suite</span> <span class="string">"example"</span> 88</pre> 89 </td></tr></tbody> 90</table></div> 91<p> 92 To use second layer your predicate has to return <code class="computeroutput"><a class="link" href="../../header/boost/test/tools/assertion_result_hpp.html#boost.test_tools.predicate_result">boost::test_tools::predicate_result</a></code>. 93 </p> 94<p> 95 This class encapsulates boolean result value along with any error or information 96 message you opt to report. 97 </p> 98<p> 99 Usually you construct the instance of class <code class="computeroutput"><a class="link" href="../../header/boost/test/tools/assertion_result_hpp.html#boost.test_tools.predicate_result">boost::test_tools::predicate_result</a></code> 100 inside your predicate function and return it by value. The constructor expects 101 one argument - the boolean result value. The constructor is implicit, so 102 you can simply return boolean value from your predicate and <code class="computeroutput"><a class="link" href="../../header/boost/test/tools/assertion_result_hpp.html#boost.test_tools.predicate_result">boost::test_tools::predicate_result</a></code> 103 is constructed automatically to hold your value and empty message. You can 104 also assign boolean value to the constructed instance. You can check the 105 current predicate value by using <code class="computeroutput"><span class="keyword">operator</span><span class="special">!</span></code> or directly accessing public read-only property 106 <code class="computeroutput"><span class="identifier">p_predicate_value</span></code>. The error 107 message is stored in public read-write property <code class="computeroutput"><span class="identifier">p_message</span></code>. 108 </p> 109<h6> 110<a name="boost_test.testing_tools.custom_predicates.h1"></a> 111 <span class="phrase"><a name="boost_test.testing_tools.custom_predicates.example_descr0"></a></span><a class="link" href="custom_predicates.html#boost_test.testing_tools.custom_predicates.example_descr0">Example: 112 Custom predicate support using class boost::test_tools::predicate_result</a> 113 </h6> 114<div class="informaltable"><table class="table"> 115<colgroup><col></colgroup> 116<thead><tr><th> 117 <p> 118 Code 119 </p> 120 </th></tr></thead> 121<tbody><tr><td> 122<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="preprocessor">#define</span> <span class="identifier">BOOST_TEST_MODULE</span> <span class="identifier">example</span> 123<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">test</span><span class="special">/</span><span class="identifier">included</span><span class="special">/</span><span class="identifier">unit_test</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 124 125<span class="identifier">boost</span><span class="special">::</span><span class="identifier">test_tools</span><span class="special">::</span><span class="identifier">predicate_result</span> 126 <span class="identifier">compare_lists</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">l1</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">l2</span> <span class="special">)</span> 127<span class="special">{</span> 128 <span class="keyword">if</span><span class="special">(</span> <span class="identifier">l1</span><span class="special">.</span><span class="identifier">size</span><span class="special">()</span> <span class="special">!=</span> <span class="identifier">l2</span><span class="special">.</span><span class="identifier">size</span><span class="special">()</span> <span class="special">)</span> 129 <span class="special">{</span> 130 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">test_tools</span><span class="special">::</span><span class="identifier">predicate_result</span> <span class="identifier">res</span><span class="special">(</span> <span class="keyword">false</span> <span class="special">);</span> 131 132 <span class="identifier">res</span><span class="special">.</span><span class="identifier">message</span><span class="special">()</span> <span class="special"><<</span> <span class="string">"Different sizes ["</span> <span class="special"><<</span> <span class="identifier">l1</span><span class="special">.</span><span class="identifier">size</span><span class="special">()</span> <span class="special"><<</span> <span class="string">"!="</span> <span class="special"><<</span> <span class="identifier">l2</span><span class="special">.</span><span class="identifier">size</span><span class="special">()</span> <span class="special"><<</span> <span class="string">"]"</span><span class="special">;</span> 133 134 <span class="keyword">return</span> <span class="identifier">res</span><span class="special">;</span> 135 <span class="special">}</span> 136 <span class="keyword">return</span> <span class="keyword">true</span><span class="special">;</span> 137<span class="special">}</span> 138 139<span class="identifier">BOOST_AUTO_TEST_CASE</span><span class="special">(</span> <span class="identifier">test_list_comparison</span> <span class="special">)</span> 140<span class="special">{</span> 141 <span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">l1</span><span class="special">,</span> <span class="identifier">l2</span><span class="special">;</span> 142 <span class="identifier">l1</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span> <span class="number">1</span> <span class="special">);</span> 143 <span class="identifier">l1</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span> <span class="number">2</span> <span class="special">);</span> 144 145 <span class="identifier">BOOST_TEST</span><span class="special">(</span> <span class="identifier">compare_lists</span><span class="special">(</span> <span class="identifier">l1</span><span class="special">,</span> <span class="identifier">l2</span> <span class="special">)</span> <span class="special">);</span> 146<span class="special">}</span> 147</pre> 148 </td></tr></tbody> 149</table></div> 150<div class="informaltable"><table class="table"> 151<colgroup><col></colgroup> 152<thead><tr><th> 153 <p> 154 Output 155 </p> 156 </th></tr></thead> 157<tbody><tr><td> 158<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">Running</span> <span class="number">1</span> <span class="identifier">test</span> <span class="keyword">case</span><span class="special">...</span> 159<span class="identifier">test</span><span class="special">.</span><span class="identifier">cpp</span><span class="special">(</span><span class="number">28</span><span class="special">):</span> <span class="identifier">error</span> <span class="identifier">in</span> <span class="string">"test_list_comparizon"</span><span class="special">:</span> <span class="identifier">check</span> <span class="identifier">compare_lists</span><span class="special">(</span> <span class="identifier">l1</span><span class="special">,</span> <span class="identifier">l2</span> <span class="special">)</span> <span class="identifier">has</span> <span class="identifier">failed</span><span class="special">.</span> <span class="identifier">Different</span> <span class="identifier">sizes</span> <span class="special">[</span><span class="number">2</span><span class="special">!=</span><span class="number">0</span><span class="special">]</span> 160 161<span class="special">***</span> <span class="number">1</span> <span class="identifier">failures</span> <span class="identifier">is</span> <span class="identifier">detected</span> <span class="identifier">in</span> <span class="identifier">test</span> <span class="identifier">suite</span> <span class="string">"example"</span> 162</pre> 163 </td></tr></tbody> 164</table></div> 165</div> 166<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 167<td align="left"></td> 168<td align="right"><div class="copyright-footer">Copyright © 2001-2020 Boost.Test contributors<p> 169 Distributed under the Boost Software License, Version 1.0. (See accompanying 170 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 171 </p> 172</div></td> 173</tr></table> 174<hr> 175<div class="spirit-nav"> 176<a accesskey="p" href="expected_failures.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../testing_tools.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="output_stream_testing.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 177</div> 178</body> 179</html> 180
