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- <div class="titlepage"><div><div><h3 class="title">
- <a name="boost_test.testing_tools.output_stream_testing"></a><a class="link" href="output_stream_testing.html" title="Output streams testing tool">Output
- streams testing tool</a>
- </h3></div></div></div>
- <p>
- How would you perform correctness test for
- </p>
- <pre class="programlisting"><span class="keyword">operator</span><span class="special"><<</span> <span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span> <span class="special">&,</span> <span class="special">...</span> <span class="special">)</span></pre>
- <p>
- operations?
- </p>
- <p>
- You can print into the standard output stream and manually check that it
- is matching your expectations. Unfortunately, this is not really acceptable
- for the regression testing and doesn't serve a long term purpose of a unit
- test.
- </p>
- <p>
- You can use <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">stringstream</span></code> and compare resulting output
- buffer with the expected pattern string, but you are required to perform
- several additional operations with every check you do. So it becomes tedious
- very fast.
- </p>
- <p>
- The class <code class="computeroutput"><a class="link" href="../../boost/test_tools/output_test_stream.html" title="Class output_test_stream">boost::test_tools::output_test_stream</a></code>
- is designed to automate these tasks for you. This is a simple, but powerful
- tool for testing standard <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span></code>
- based output operation. The class <code class="computeroutput"><span class="identifier">output_test_stream</span></code>
- complies to <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span></code> interface so it can be used in
- place of any <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span></code> parameter. It provides several
- test methods to validate output content, including test for match to expected
- output content or test for expected output length. Flushing, synchronizing,
- string comparison and error message generation is automated by the tool implementation.
- </p>
- <p>
- All <code class="computeroutput"><span class="identifier">output_test_stream</span></code> validation
- member functions by default flush the stream once the check is performed.
- If you want to perform several checks with the same output, specify parameter
- <code class="computeroutput"><span class="identifier">flush_stream</span></code> with value
- <code class="computeroutput"><span class="keyword">false</span></code> <a href="#ftn.boost_test.testing_tools.output_stream_testing.f0" class="footnote" name="boost_test.testing_tools.output_stream_testing.f0"><sup class="footnote">[16]</sup></a>.
- </p>
- <p>
- In some cases manual generation of expected output is either too time consuming
- or is impossible at all because of sheer volume. A possible way to address
- that issue is to split the test in two steps:
- </p>
- <div class="orderedlist"><ol class="orderedlist" type="1">
- <li class="listitem">
- first by checking the expected output manually
- </li>
- <li class="listitem">
- second to save this output to ensure that future checks produce the same
- output
- </li>
- </ol></div>
- <p>
- The class <code class="computeroutput"><span class="identifier">output_test_stream</span></code>
- allows both the matching of the output content versus a <span class="emphasis"><em>pattern
- file</em></span> and generation of this pattern file. The command line parameter
- <a class="link" href="../utf_reference/rt_param_reference/save_pattern.html" title="save_pattern"><code class="computeroutput"><span class="identifier">save_pattern</span></code></a> may be used to either
- generate a new pattern file, or to check against an existing pattern.
- </p>
- <h4>
- <a name="boost_test.testing_tools.output_stream_testing.h0"></a>
- <span class="phrase"><a name="boost_test.testing_tools.output_stream_testing.usages"></a></span><a class="link" href="output_stream_testing.html#boost_test.testing_tools.output_stream_testing.usages">Usage</a>
- </h4>
- <p>
- There are two ways to employ the class <code class="computeroutput"><span class="identifier">output_test_stream</span></code>:
- </p>
- <div class="orderedlist"><ol class="orderedlist" type="1">
- <li class="listitem">
- explicit output checks and
- </li>
- <li class="listitem">
- pattern file matching
- </li>
- </ol></div>
- <h5>
- <a name="boost_test.testing_tools.output_stream_testing.h1"></a>
- <span class="phrase"><a name="boost_test.testing_tools.output_stream_testing.explicit_output_checks"></a></span><a class="link" href="output_stream_testing.html#boost_test.testing_tools.output_stream_testing.explicit_output_checks">Explicit
- output checks</a>
- </h5>
- <p>
- Use the instance of class <code class="computeroutput"><span class="identifier">output_test_stream</span></code>
- as an output stream and check output content using tool's methods.
- </p>
- <h6>
- <a name="boost_test.testing_tools.output_stream_testing.h2"></a>
- <span class="phrase"><a name="boost_test.testing_tools.output_stream_testing.example_descr"></a></span><a class="link" href="output_stream_testing.html#boost_test.testing_tools.output_stream_testing.example_descr">Example:
- Explicit output checks with <code class="computeroutput"><span class="identifier">output_test_stream</span></code></a>
- </h6>
- <div class="informaltable"><table class="table">
- <colgroup><col></colgroup>
- <thead><tr><th>
- <p>
- Code
- </p>
- </th></tr></thead>
- <tbody><tr><td>
- <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>
- <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>
- <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">tools</span><span class="special">/</span><span class="identifier">output_test_stream</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
- <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">test_tools</span><span class="special">::</span><span class="identifier">output_test_stream</span><span class="special">;</span>
- <span class="identifier">BOOST_AUTO_TEST_CASE</span><span class="special">(</span> <span class="identifier">test</span> <span class="special">)</span>
- <span class="special">{</span>
- <span class="identifier">output_test_stream</span> <span class="identifier">output</span><span class="special">;</span>
- <span class="keyword">int</span> <span class="identifier">i</span><span class="special">=</span><span class="number">2</span><span class="special">;</span>
- <span class="identifier">output</span> <span class="special"><<</span> <span class="string">"i="</span> <span class="special"><<</span> <span class="identifier">i</span><span class="special">;</span>
- <span class="identifier">BOOST_TEST</span><span class="special">(</span> <span class="special">!</span><span class="identifier">output</span><span class="special">.</span><span class="identifier">is_empty</span><span class="special">(</span> <span class="keyword">false</span> <span class="special">)</span> <span class="special">);</span>
- <span class="identifier">BOOST_TEST</span><span class="special">(</span> <span class="identifier">output</span><span class="special">.</span><span class="identifier">check_length</span><span class="special">(</span> <span class="number">3</span><span class="special">,</span> <span class="keyword">false</span> <span class="special">)</span> <span class="special">);</span>
- <span class="identifier">BOOST_TEST</span><span class="special">(</span> <span class="identifier">output</span><span class="special">.</span><span class="identifier">is_equal</span><span class="special">(</span> <span class="string">"i=3"</span> <span class="special">)</span> <span class="special">);</span>
- <span class="special">}</span>
- </pre>
- </td></tr></tbody>
- </table></div>
- <div class="informaltable"><table class="table">
- <colgroup><col></colgroup>
- <thead><tr><th>
- <p>
- Output
- </p>
- </th></tr></thead>
- <tbody><tr><td>
- <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>
- <span class="identifier">Running</span> <span class="number">1</span> <span class="identifier">test</span> <span class="keyword">case</span><span class="special">...</span>
- <span class="identifier">test</span><span class="special">.</span><span class="identifier">cpp</span><span class="special">(</span><span class="number">15</span><span class="special">):</span> <span class="identifier">error</span> <span class="identifier">in</span> <span class="string">"test"</span><span class="special">:</span> <span class="identifier">check</span> <span class="identifier">output</span><span class="special">.</span><span class="identifier">is_equal</span><span class="special">(</span> <span class="string">"i=3"</span> <span class="special">)</span> <span class="identifier">has</span> <span class="identifier">failed</span><span class="special">.</span> <span class="identifier">Output</span> <span class="identifier">content</span><span class="special">:</span> <span class="string">"i=2"</span>
- <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>
- </pre>
- </td></tr></tbody>
- </table></div>
- <div class="note"><table border="0" summary="Note">
- <tr>
- <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td>
- <th align="left">Note</th>
- </tr>
- <tr><td align="left" valign="top"><p>
- Use of <code class="computeroutput"><span class="keyword">false</span></code> to prevent output
- flushing in first two invocation of check functions. Unless you want to
- perform several different checks for the same output you wouldn't need
- to use it though. Your test will look like a sequence of output operators
- followed by one check.
- </p></td></tr>
- </table></div>
- <div class="tip"><table border="0" summary="Tip">
- <tr>
- <td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../../../../doc/src/images/tip.png"></td>
- <th align="left">Tip</th>
- </tr>
- <tr><td align="left" valign="top"><p>
- Try to perform checks as frequently as possible. It not only simplifies
- patterns you compare with, but also allows you to more closely identify
- possible source of failure.
- </p></td></tr>
- </table></div>
- <h5>
- <a name="boost_test.testing_tools.output_stream_testing.h3"></a>
- <span class="phrase"><a name="boost_test.testing_tools.output_stream_testing.pattern_file_matching"></a></span><a class="link" href="output_stream_testing.html#boost_test.testing_tools.output_stream_testing.pattern_file_matching">Pattern
- file matching</a>
- </h5>
- <p>
- The <span class="emphasis"><em>pattern file</em></span> is a companion file containing the
- patterns that the stream should match. Your testing will look like a series
- of output operators followed by match pattern checks repeated several times.
- </p>
- <p>
- In the example below, the file <code class="computeroutput"><span class="identifier">pattern_file</span></code>
- contains the patterns that should match.
- </p>
- <pre class="programlisting">i=2
- File: test.cpp Line:XXX
- </pre>
- <h6>
- <a name="boost_test.testing_tools.output_stream_testing.h4"></a>
- <span class="phrase"><a name="boost_test.testing_tools.output_stream_testing.example_descr0"></a></span><a class="link" href="output_stream_testing.html#boost_test.testing_tools.output_stream_testing.example_descr0">Example:
- Pattern file matching with <code class="computeroutput"><span class="identifier">output_test_stream</span></code></a>
- </h6>
- <div class="informaltable"><table class="table">
- <colgroup><col></colgroup>
- <thead><tr><th>
- <p>
- Code
- </p>
- </th></tr></thead>
- <tbody><tr><td>
- <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>
- <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>
- <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">tools</span><span class="special">/</span><span class="identifier">output_test_stream</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
- <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">test_tools</span><span class="special">::</span><span class="identifier">output_test_stream</span><span class="special">;</span>
- <span class="identifier">BOOST_AUTO_TEST_CASE</span><span class="special">(</span> <span class="identifier">test</span> <span class="special">)</span>
- <span class="special">{</span>
- <span class="identifier">output_test_stream</span> <span class="identifier">output</span><span class="special">(</span> <span class="string">"pattern_file"</span><span class="special">,</span> <span class="special">!</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unit_test</span><span class="special">::</span><span class="identifier">runtime_config</span><span class="special">::</span><span class="identifier">save_pattern</span><span class="special">()</span> <span class="special">);</span>
- <span class="keyword">int</span> <span class="identifier">i</span><span class="special">=</span><span class="number">2</span><span class="special">;</span>
- <span class="identifier">output</span> <span class="special"><<</span> <span class="string">"i="</span> <span class="special"><<</span> <span class="identifier">i</span><span class="special">;</span>
- <span class="identifier">BOOST_TEST</span><span class="special">(</span> <span class="identifier">output</span><span class="special">.</span><span class="identifier">match_pattern</span><span class="special">()</span> <span class="special">);</span>
- <span class="identifier">output</span> <span class="special"><<</span> <span class="string">"\nFile: "</span> <span class="special"><<</span> <span class="identifier">__FILE__</span> <span class="special"><<</span> <span class="string">" Line:YYY"</span><span class="special">;</span>
- <span class="identifier">BOOST_TEST</span><span class="special">(</span> <span class="identifier">output</span><span class="special">.</span><span class="identifier">match_pattern</span><span class="special">()</span> <span class="special">);</span> <a class="co" name="boost_test.testing_tools.output_stream_testing.c0" href="output_stream_testing.html#boost_test.testing_tools.output_stream_testing.c1"><img src="../../../../../../doc/src/images/callouts/1.png" alt="1" border="0"></a>
- <span class="special">}</span>
- </pre>
- <div class="calloutlist"><table border="0" summary="Callout list"><tr>
- <td width="5%" valign="top" align="left"><p><a name="boost_test.testing_tools.output_stream_testing.c1"></a><a href="#boost_test.testing_tools.output_stream_testing.c0"><img src="../../../../../../doc/src/images/callouts/1.png" alt="1" border="0"></a> </p></td>
- <td valign="top" align="left"><p>
- This line generates the error Line:YYY != Line:XXX
- </p></td>
- </tr></table></div>
- </td></tr></tbody>
- </table></div>
- <div class="informaltable"><table class="table">
- <colgroup><col></colgroup>
- <thead><tr><th>
- <p>
- Output
- </p>
- </th></tr></thead>
- <tbody><tr><td>
- <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>
- <span class="identifier">Running</span> <span class="number">1</span> <span class="identifier">test</span> <span class="keyword">case</span><span class="special">...</span>
- <span class="identifier">test</span><span class="special">.</span><span class="identifier">cpp</span><span class="special">(</span><span class="number">16</span><span class="special">):</span> <span class="identifier">error</span> <span class="identifier">in</span> <span class="string">"test"</span><span class="special">:</span> <span class="identifier">check</span> <span class="identifier">output</span><span class="special">.</span><span class="identifier">match_pattern</span><span class="special">()</span> <span class="identifier">has</span> <span class="identifier">failed</span><span class="special">.</span> <span class="identifier">Mismatch</span> <span class="identifier">at</span> <span class="identifier">position</span> <span class="number">23</span>
- <span class="special">...</span><span class="number">5.</span><span class="special">..</span>
- <span class="special">...</span><span class="number">4.</span><span class="special">..</span>
- <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>
- </pre>
- </td></tr></tbody>
- </table></div>
- <div class="tip"><table border="0" summary="Tip">
- <tr>
- <td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../../../../doc/src/images/tip.png"></td>
- <th align="left">Tip</th>
- </tr>
- <tr><td align="left" valign="top"><p>
- Try to perform checks as frequently as possible, because it allows you
- to more closely identify possible source of failure
- </p></td></tr>
- </table></div>
- <div class="footnotes">
- <br><hr style="width:100; text-align:left;margin-left: 0">
- <div id="ftn.boost_test.testing_tools.output_stream_testing.f0" class="footnote"><p><a href="#boost_test.testing_tools.output_stream_testing.f0" class="para"><sup class="para">[16] </sup></a>
- This parameter is supported on all comparison methods, see the class <code class="computeroutput"><a class="link" href="../../boost/test_tools/output_test_stream.html" title="Class output_test_stream">documentation.</a></code>
- </p></div>
- </div>
- </div>
- <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
- <td align="left"></td>
- <td align="right"><div class="copyright-footer">Copyright © 2001-2019 Boost.Test
- contributors<p>
- Distributed under the Boost Software License, Version 1.0. (See accompanying
- 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>)
- </p>
- </div></td>
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