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Apache::TestSmoke(3)                 User Contributed Perl Documentation                Apache::TestSmoke(3)



NAME
       Apache::TestSmoke - Special Tests Sequence Failure Finder

SYNOPSIS
         # get the usage and the default values
         % t/SMOKE -help

         # repeat all tests 5 times and save the report into
         # the file 'myreport'
         % t/SMOKE -times=5 -report=myreport

         # run all tests default number of iterations, and repeat tests
         # default number of times
         % t/SMOKE

         # same as above but work only the specified tests
         % t/SMOKE foo/bar foo/tar

         # run once a sequence of tests in a non-random mode
         # e.g. when trying to reduce a known long sequence that fails
         % t/SMOKE -order=rotate -times=1 foo/bar foo/tar

         # show me each currently running test
         # it's not the same as running the tests in the verbose mode
         % t/SMOKE -verbose

         # run t/TEST, but show any problems after *each* tests is run
         # useful for bug reports (it actually runs t/TEST -start, then
         # t/TEST -run for each test separately and finally t/TEST -stop
         % t/SMOKE -bug_mode

         # now read the created report file

DESCRIPTION
   The Problem
       When we try to test a stateless machine (i.e. all tests are independent), running all tests once
       ensures that all tested things properly work. However when a state machine is tested (i.e. where a
       run of one test may influence another test) it's not enough to run all the tests once to know that
       the tested features actually work. It's quite possible that if the same tests are run in a different
       order and/or repeated a few times, some tests may fail.  This usually happens when some tests don't
       restore the system under test to its pristine state at the end of the run, which may influence other
       tests which rely on the fact that they start on pristine state, when in fact it's not true anymore.
       In fact it's possible that a single test may fail when run twice or three times in a sequence.

   The Solution
       To reduce the possibility of such dependency errors, it's helpful to run random testing repeated many
       times with many different srand seeds. Of course if no failures get spotted that doesn't mean that
       there are no tests inter-dependencies, which may cause a failure in production. But random testing
       definitely helps to spot many problems and can give better test coverage.

   Resolving Sequence Problems
       When this kind of testing is used and a failure is detected there are two problems:

       1.  First is to be able to reproduce the problem so if we think we fixed it, we could verify the fix.
           This one is easy, just remember the sequence of tests run till the failed test and rerun the same
           sequence once again after the problem has been fixed.

       2.  Second is to be able to understand the cause of the problem. If during the random test the
           failure has happened after running 400 tests, how can we possibly know which previously running
           tests has caused to the failure of the test 401. Chances are that most of the tests were clean
           and don't have inter-dependency problem. Therefore it'd be very helpful if we could reduce the
           long sequence to a minimum. Preferably 1 or 2 tests. That's when we can try to understand the
           cause of the detected problem.

       This utility attempts to solve both problems, and at the end of each iteration print a minimal
       sequence of tests causing to a failure. This doesn't always succeed, but works in many cases.

       This utility:

       1.  Runs the tests randomly until the first failure is detected. Or non-randomly if the option -order
           is set to repeat or rotate.

       2.  Then it tries to reduce that sequence of tests to a minimum, and this sequence still causes to
           the same failure.

       3.  (XXX: todo): then it reruns the minimal sequence in the verbose mode and saves the output.

       4.  It reports all the successful reductions as it goes to STDOUT and report file of the format:
           smoke-report-<date>.txt.

           In addition the systems build parameters are logged into the report file, so the detected
           problems could be reproduced.

       5.  Goto 1 and run again using a new random seed, which potentially should detect different failures.

Reduction Algorithm
       Currently for each reduction path, the following reduction algorithms get applied:

       1.  Binary search: first try the upper half then the lower.

       2.  Random window: randomize the left item, then the right item and return the items between these
           two points.

t/SMOKE.PL
       t/SMOKE.PL is driving this module, if you don't have it, create it:

         #!perl

         use strict;
         use warnings FATAL => 'all';

         use FindBin;
         use lib "$FindBin::Bin/../Apache-Test/lib";
         use lib "$FindBin::Bin/../lib";

         use Apache::TestSmoke ();

         Apache::TestSmoke->new(@ARGV)->run;

       usually Makefile.PL converts it into t/SMOKE while adjusting the perl path, but you create t/SMOKE in
       first place as well.

AUTHOR
       Stas Bekman



perl v5.16.2                                     2011-02-07                             Apache::TestSmoke(3)