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76 lines
4.4 KiB
HTML
76 lines
4.4 KiB
HTML
<HTML>
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<HEAD>
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<TITLE>The Test Tools</TITLE>
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<LINK rel="stylesheet" type="text/css" href="../../../style/btl.css" media="screen">
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<LINK rel="stylesheet" type="text/css" href="../../../style/btl-print.css" media="print">
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<META http-equiv="Content-Language" content="en-us">
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<META http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<STYLE type="text/css">
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H4
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{
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margin: 0px;
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}
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</STYLE>
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</HEAD>
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<BODY>
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<DIV class="body">
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<H3>BOOST_CHECK_CLOSE( left, right, tolerance_src )</H3>
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<P class="first-line-indented">This tool is used to check <I>left</I> and <I>right</I> values on closeness
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using strong relationship defined by the predicate <A href="../floating_point_comparison.html" target="_top">close_at_tolerance
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</A>( tolerance_src ). To check for the weak relationship use <A href="BOOST_CHECK_PREDICATE.html">BOOST_CHECK_PREDICATE</A>
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tool. Note that to use this tool you need to include additional header<A href="../../../../../../boost/test/floating_point_comparison.hpp">
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floating_point_comparison.hpp</A>, since tools implementation depends on this file that does not get
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included automatically to minimize code dependency. </P>
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<P class="first-line-indented">If comparison is successful, the tool produces a confirmation message
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(note: to manage what messages appear in the test output stream set the proper log level) in other
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case it produces an error message in a form "error in <test case name>: test <<I>left</I>
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argument name> (==) <<I>right</I> argument name> failed [ <<I>left</I> argument value>
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!= <<I>right</I> argument value> (<real predicate value>)]".</P>
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<P class="first-line-indented"></P>
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<P class="first-line-indented">The tool's first parameter is the <I>left</I> compared value. The tool's
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second parameter is the <I>right</I> compared value. Last third parameter defines the tolerance for
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the comparison in percentage units. For more details how to treat this value
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see <A href="../floating_point_comparison.html" target="_top">close_at_tolerance </A>description.
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Note that it required for <I>left</I> and <I>right</I> parameters to be of the same floating point
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type. You need to explicitly resolve any type mismatch to select which type to use for comparison.</P>
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<H4>Example: test.cpp</H4>
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<PRE class="code"><SPAN class="cpp-type">int</SPAN> test_main( <SPAN class="cpp-type">int</SPAN>, <SPAN class="cpp-type">char</SPAN>* [] ) {
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<SPAN class="cpp-type">double</SPAN> v1 = <SPAN class="literal">1.23456e-10</SPAN>;
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<SPAN class="cpp-type">double</SPAN> v2 = <SPAN class="literal">1.23457e-10</SPAN>;
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BOOST_CHECK_CLOSE( v1, v2, <SPAN class="literal">0.0001</SPAN> );
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<SPAN class="comment">// Absolute value of difference between these two values is 1e-15. They seems
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// to be very close. But we want to checks that these values differ no more then 0.0001%
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// of their value. And this test will fail at tolerance supplied</SPAN>.
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<SPAN class="reserv-word">return</SPAN> <SPAN class="literal">0</SPAN>;
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}</PRE>
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<H4>Output:</H4>
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<P class="test-output">test.cpp(4) : error in test_main: difference between
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v1{1.23456e-10} and v2{1.23457e-10} exeeds 1e-04%</P>
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<H4>Example: test.cpp</H4>
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<PRE class="code"><SPAN class="cpp-type">int</SPAN> test_main( <SPAN class="cpp-type">int</SPAN>, <SPAN class="cpp-type">char</SPAN>* [] ) {
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<SPAN class="cpp-type">double</SPAN> v1 = <SPAN class="literal">1.23456e28;</SPAN>
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<SPAN class="cpp-type">double</SPAN> v2 = <SPAN class="literal">1.23457e28;</SPAN>
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BOOST_CHECK_CLOSE( v1, v2, <SPAN class="literal">0.001</SPAN> );
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<SPAN class="comment">// Absolute value of difference between these two values is 1e+23.
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// But we are interested only that it does not exeed 0.001% of a values compared
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// And this test will pass.</SPAN>
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<SPAN class="reserv-word">return</SPAN> <SPAN class="literal">0</SPAN>;
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}</PRE>
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<H4>Output:</H4>
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<P class="test-output"> </P>
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<DIV class="see_also">
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<H4>See Also</H4>
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<P class="see-also-content"><A href="BOOST_CHECK_EQUAL.html" target="descr">BOOST_CHECK_EQUAL</A>,
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<A href="../floating_point_comparison.html" target="_top">Floating point comparison algorithms</A></P>
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</DIV>
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</DIV>
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</BODY>
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</HTML>
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<!-- Copyright Gennadiy Rozental 2001-2004.
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or copy at www.boost.org/LICENSE_1_0.txt) -->
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