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1<?xml version="1.0" encoding="UTF-8" standalone="no"?>2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>33.3. Variant Comparison Files</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="regress-evaluation.html" title="33.2. Test Evaluation" /><link rel="next" href="regress-tap.html" title="33.4. TAP Tests" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">33.3. Variant Comparison Files</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="regress-evaluation.html" title="33.2. Test Evaluation">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="regress.html" title="Chapter 33. Regression Tests">Up</a></td><th width="60%" align="center">Chapter 33. Regression Tests</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="regress-tap.html" title="33.4. TAP Tests">Next</a></td></tr></table><hr /></div><div class="sect1" id="REGRESS-VARIANT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">33.3. Variant Comparison Files <a href="#REGRESS-VARIANT" class="id_link">#</a></h2></div></div></div><p>3    Since some of the tests inherently produce environment-dependent4    results, we have provided ways to specify alternate <span class="quote">“<span class="quote">expected</span>”</span>5    result files.  Each regression test can have several comparison files6    showing possible results on different platforms.  There are two7    independent mechanisms for determining which comparison file is used8    for each test.9   </p><p>10    The first mechanism allows comparison files to be selected for11    specific platforms.  There is a mapping file,12    <code class="filename">src/test/regress/resultmap</code>, that defines13    which comparison file to use for each platform.14    To eliminate bogus test <span class="quote">“<span class="quote">failures</span>”</span> for a particular platform,15    you first choose or make a variant result file, and then add a line to the16    <code class="filename">resultmap</code> file.17   </p><p>18    Each line in the mapping file is of the form19</p><pre class="synopsis">20testname:output:platformpattern=comparisonfilename21</pre><p>22    The test name is just the name of the particular regression test23    module. The output value indicates which output file to check. For the24    standard regression tests, this is always <code class="literal">out</code>. The25    value corresponds to the file extension of the output file.26    The platform pattern is a pattern in the style of the Unix27    tool <code class="command">expr</code> (that is, a regular expression with an implicit28    <code class="literal">^</code> anchor at the start).  It is matched against the29    platform name as printed by <code class="command">config.guess</code>.30    The comparison file name is the base name of the substitute result31    comparison file.32   </p><p>33    For example: some systems lack a working <code class="literal">strtof</code> function,34    for which our workaround causes rounding errors in the35    <code class="filename">float4</code> regression test.36    Therefore, we provide a variant comparison file,37    <code class="filename">float4-misrounded-input.out</code>, which includes38    the results to be expected on these systems.  To silence the bogus39    <span class="quote">“<span class="quote">failure</span>”</span> message on <span class="systemitem">Cygwin</span>40    platforms, <code class="filename">resultmap</code> includes:41</p><pre class="programlisting">42float4:out:.*-.*-cygwin.*=float4-misrounded-input.out43</pre><p>44    which will trigger on any machine where the output of45    <code class="command">config.guess</code> matches <code class="literal">.*-.*-cygwin.*</code>.46    Other lines in <code class="filename">resultmap</code> select the variant comparison47    file for other platforms where it's appropriate.48   </p><p>49    The second selection mechanism for variant comparison files is50    much more automatic: it simply uses the <span class="quote">“<span class="quote">best match</span>”</span> among51    several supplied comparison files.  The regression test driver52    script considers both the standard comparison file for a test,53    <code class="literal"><em class="replaceable"><code>testname</code></em>.out</code>, and variant files named54    <code class="literal"><em class="replaceable"><code>testname</code></em>_<em class="replaceable"><code>digit</code></em>.out</code>55    (where the <em class="replaceable"><code>digit</code></em> is any single digit56    <code class="literal">0</code>-<code class="literal">9</code>).  If any such file is an exact match,57    the test is considered to pass; otherwise, the one that generates58    the shortest diff is used to create the failure report.  (If59    <code class="filename">resultmap</code> includes an entry for the particular60    test, then the base <em class="replaceable"><code>testname</code></em> is the substitute61    name given in <code class="filename">resultmap</code>.)62   </p><p>63    For example, for the <code class="literal">char</code> test, the comparison file64    <code class="filename">char.out</code> contains results that are expected65    in the <code class="literal">C</code> and <code class="literal">POSIX</code> locales, while66    the file <code class="filename">char_1.out</code> contains results sorted as67    they appear in many other locales.68   </p><p>69    The best-match mechanism was devised to cope with locale-dependent70    results, but it can be used in any situation where the test results71    cannot be predicted easily from the platform name alone.  A limitation of72    this mechanism is that the test driver cannot tell which variant is73    actually <span class="quote">“<span class="quote">correct</span>”</span> for the current environment; it will just pick74    the variant that seems to work best.  Therefore it is safest to use this75    mechanism only for variant results that you are willing to consider76    equally valid in all contexts.77   </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="regress-evaluation.html" title="33.2. Test Evaluation">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="regress.html" title="Chapter 33. Regression Tests">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="regress-tap.html" title="33.4. TAP Tests">Next</a></td></tr><tr><td width="40%" align="left" valign="top">33.2. Test Evaluation </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 33.4. TAP Tests</td></tr></table></div></body></html>