regress.sgml

PostgreSQL7.4.6 for Linux

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 <chapter id="regress">
  <title id="regress-title">Regression Tests</title>

  <indexterm zone="regress">
   <primary>regression tests</primary>
  </indexterm>

  <indexterm zone="regress">
   <primary>test</primary>
  </indexterm>

  <para>
   The regression tests are a comprehensive set of tests for the SQL
   implementation in <productname>PostgreSQL</productname>.  They test
   standard SQL operations as well as the extended capabilities of
   <productname>PostgreSQL</productname>.  From
   <productname>PostgreSQL</productname> 6.1 onward, the regression
   tests are current for every official release.
  </para>

  <sect1 id="regress-run">
   <title>Running the Tests</title>

  <para>
   The regression test can be run against an already installed and
   running server, or using a temporary installation within the build
   tree.  Furthermore, there is a <quote>parallel</quote> and a
   <quote>sequential</quote> mode for running the tests.  The
   sequential method runs each test script in turn, whereas the
   parallel method starts up multiple server processes to run groups
   of tests in parallel.  Parallel testing gives confidence that
   interprocess communication and locking are working correctly.  For
   historical reasons, the sequential test is usually run against an
   existing installation and the parallel method against a temporary
   installation, but there are no technical reasons for this.
  </para>

  <para>
   To run the regression tests after building but before installation,
   type
<screen>
gmake check
</screen>
   in the top-level directory.  (Or you can change to
   <filename>src/test/regress</filename> and run the command there.)
   This will first build several auxiliary files, such as
   some sample
   user-defined trigger functions, and then run the test driver
   script.  At the end you should see something like
<screen>
<computeroutput>
======================
 All 93 tests passed.
======================
</computeroutput>
</screen>
   or otherwise a note about which tests failed.  See <xref
   linkend="regress-evaluation"> below for more.
  </para>

   <para>
    Because this test method runs a temporary server, it will not work
    when you are the root user (since the server will not start as root).
    If you already did the build as root, you do not have to start all
    over.  Instead, make the regression test directory writable by
    some other user, log in as that user, and restart the tests.
    For example
<screen>
<prompt>root# </prompt><userinput>chmod -R a+w src/test/regress</userinput>
<prompt>root# </prompt><userinput>chmod -R a+w contrib/spi</userinput>
<prompt>root# </prompt><userinput>su - joeuser</userinput>
<prompt>joeuser$ </prompt><userinput>cd <replaceable>top-level build directory</></userinput>
<prompt>joeuser$ </prompt><userinput>gmake check</userinput>
</screen>
    (The only possible <quote>security risk</quote> here is that other
    users might be able to alter the regression test results behind
    your back.  Use common sense when managing user permissions.)
   </para>
   <para>
    Alternatively, run the tests after installation.
   </para>

   <para>
    The parallel regression test starts quite a few processes under your
    user ID.  Presently, the maximum concurrency is twenty parallel test
    scripts, which means sixty processes: there's a server process, a
    <application>psql</>, and usually a shell parent process for the
    <application>psql</> for each test script.
    So if your system enforces a per-user limit on the number of processes,
    make sure this limit is at least seventy-five or so, else you may get
    random-seeming failures in the parallel test.  If you are not in
    a position to raise the limit, you can cut down the degree of parallelism
    by setting the <literal>MAX_CONNECTIONS</> parameter.  For example,
<screen>
gmake MAX_CONNECTIONS=10 check
</screen>
    runs no more than ten tests concurrently.
   </para>

   <para>
    On some systems, the default Bourne-compatible shell
    (<filename>/bin/sh</filename>) gets confused when it has to manage
    too many child processes in parallel.  This may cause the parallel
    test run to lock up or fail.  In such cases, specify a different
    Bourne-compatible shell on the command line, for example:
<screen>
gmake SHELL=/bin/ksh check
</screen>
    If no non-broken shell is available, you may be able to work around the
    problem by limiting the number of connections, as shown above.
   </para>

  <para>
   To run the tests after installation<![%standalone-ignore;[ (see <xref linkend="installation">)]]>,
   initialize a data area and start the
   server, <![%standalone-ignore;[as explained in <xref linkend="runtime">, ]]> then type
<screen>
gmake installcheck
</screen>
   The tests will expect to contact the server at the local host and the
   default port number, unless directed otherwise by <envar>PGHOST</envar> and <envar>PGPORT</envar>
   environment variables.
  </para>
  </sect1>

  <sect1 id="regress-evaluation">
   <title>Test Evaluation</title> 

   <para>
    Some properly installed and fully functional
    <productname>PostgreSQL</productname> installations can
    <quote>fail</quote> some of these regression tests due to
    platform-specific artifacts such as varying floating-point representation
    and time zone support. The tests are currently evaluated using a simple
    <command>diff</command> comparison against the outputs
    generated on a reference system, so the results are sensitive to
    small system differences.  When a test is reported as
    <quote>failed</quote>, always examine the differences between
    expected and actual results; you may well find that the
    differences are not significant.  Nonetheless, we still strive to
    maintain accurate reference files across all supported platforms,
    so it can be expected that all tests pass.
   </para>

   <para>
    The actual outputs of the regression tests are in files in the
    <filename>src/test/regress/results</filename> directory. The test
    script uses <command>diff</command> to compare each output
    file against the reference outputs stored in the
    <filename>src/test/regress/expected</filename> directory.  Any
    differences are saved for your inspection in
    <filename>src/test/regress/regression.diffs</filename>.  (Or you
    can run <command>diff</command> yourself, if you prefer.)
   </para>

   <sect2>
    <title>Error message differences</title>
      
    <para>
     Some of the regression tests involve intentional invalid input
     values.  Error messages can come from either the
     <productname>PostgreSQL</productname> code or from the host
     platform system routines. In the latter case, the messages may
     vary between platforms, but should reflect similar
     information. These differences in messages will result in a
     <quote>failed</quote> regression test that can be validated by
     inspection.
    </para>
   </sect2>
    
   <sect2>
    <title>Locale differences</title>

    <para>
     If you run the tests against an already-installed server that was
     initialized with a collation-order locale other than C, then
     there may be differences due to sort order and follow-up
     failures.  The regression test suite is set up to handle this
     problem by providing alternative result files that together are
     known to handle a large number of locales.  For example, for the
     <literal>char</literal> test, the expected file
     <filename>char.out</filename> handles the <literal>C</> and <literal>POSIX</> locales,
     and the file <filename>char_1.out</filename> handles many other
     locales.  The regression test driver will automatically pick the
     best file to match against when checking for success and for
     computing failure differences.  (This means that the regression
     tests cannot detect whether the results are appropriate for the
     configured locale.  The tests will simply pick the one result
     file that works best.)
    </para>

    <para>
     If for some reason the existing expected files do not cover some
     locale, you can add a new file.  The naming scheme is
     <literal><replaceable>testname</>_<replaceable>digit</>.out</>.
     The actual digit is not significant.  Remember that the
     regression test driver will consider all such files to be equally
     valid test results.  If the test results are platform-specific,
     the technique described in <xref linkend="regress-platform">
     should be used instead.
    </para>
   </sect2>
    
   <sect2>
    <title>Date and time differences</title>

    <para>
     A few of the queries in the <filename>horology</filename> test will
     fail if you run the test on the day of a daylight-saving time
     changeover, or the day after one.  These queries expect that
     the intervals between midnight yesterday, midnight today and