Apache::TestSmoke - Special Tests Sequence Failure Finder
# 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
# 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
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.
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
When this kind of testing is used and a failure is detected there are two
- 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.
- 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
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.
- Runs the tests randomly until the first failure is
detected. Or non-randomly if the option -order is set to
repeat or rotate.
- Then it tries to reduce that sequence of tests to a
minimum, and this sequence still causes to the same failure.
- (XXX: todo): then it reruns the minimal sequence in the
verbose mode and saves the output.
- 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.
- Goto 1 and run again using a new random seed, which
potentially should detect different failures.
Currently for each reduction path, the following reduction algorithms get
- Binary search: first try the upper half then the
- Random window: randomize the left item, then the right item
and return the items between these two points.
is driving this module, if you don't have it, create it:
use warnings FATAL => 'all';
use lib "$FindBin::Bin/../Apache-Test/lib";
use lib "$FindBin::Bin/../lib";
use Apache::TestSmoke ();
converts it into t/SMOKE
while adjusting the
perl path, but you create t/SMOKE
in first place as well.