1Apache::TestSmoke(3) User Contributed Perl Documentation Apache::TestSmoke(3)
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6 Apache::TestSmoke - Special Tests Sequence Failure Finder
7
9 # get the usage and the default values
10 % t/SMOKE -help
11 # repeat all tests 5 times and save the report into
13 # the file 'myreport'
14 % t/SMOKE -times=5 -report=myreport
15 # run all tests default number of iterations, and repeat tests
17 # default number of times
18 % t/SMOKE
19 # same as above but work only the specified tests
21 % t/SMOKE foo/bar foo/tar
22 # run once a sequence of tests in a non-random mode
24 # e.g. when trying to reduce a known long sequence that fails
25 % t/SMOKE -order=rotate -times=1 foo/bar foo/tar
26 # show me each currently running test
28 # it's not the same as running the tests in the verbose mode
29 % t/SMOKE -verbose
30 # run t/TEST, but show any problems after *each* tests is run
32 # useful for bug reports (it actually runs t/TEST -start, then
33 # t/TEST -run for each test separately and finally t/TEST -stop
34 % t/SMOKE -bug_mode
35 # now read the created report file
37
39 The Problem
40 When we try to test a stateless machine (i.e. all tests are
41 independent), running all tests once ensures that all tested things
42 properly work. However when a state machine is tested (i.e. where a run
43 of one test may influence another test) it's not enough to run all the
44 tests once to know that the tested features actually work. It's quite
45 possible that if the same tests are run in a different order and/or
46 repeated a few times, some tests may fail. This usually happens when
47 some tests don't restore the system under test to its pristine state at
48 the end of the run, which may influence other tests which rely on the
49 fact that they start on pristine state, when in fact it's not true
50 anymore. In fact it's possible that a single test may fail when run
51 twice or three times in a sequence.
52 The Solution
54 To reduce the possibility of such dependency errors, it's helpful to
55 run random testing repeated many times with many different srand seeds.
56 Of course if no failures get spotted that doesn't mean that there are
57 no tests inter-dependencies, which may cause a failure in production.
58 But random testing definitely helps to spot many problems and can give
59 better test coverage.
60 Resolving Sequence Problems
62 When this kind of testing is used and a failure is detected there are
63 two problems:
64 1. First is to be able to reproduce the problem so if we think we
66 fixed it, we could verify the fix. This one is easy, just remember
67 the sequence of tests run till the failed test and rerun the same
68 sequence once again after the problem has been fixed.
69 2. Second is to be able to understand the cause of the problem. If
71 during the random test the failure has happened after running 400
72 tests, how can we possibly know which previously running tests has
73 caused to the failure of the test 401. Chances are that most of the
74 tests were clean and don't have inter-dependency problem. Therefore
75 it'd be very helpful if we could reduce the long sequence to a
76 minimum. Preferably 1 or 2 tests. That's when we can try to
77 understand the cause of the detected problem.
78 This utility attempts to solve both problems, and at the end of each
80 iteration print a minimal sequence of tests causing to a failure. This
81 doesn't always succeed, but works in many cases.
82 This utility:
84 1. Runs the tests randomly until the first failure is detected. Or
86 non-randomly if the option -order is set to repeat or rotate.
87 2. Then it tries to reduce that sequence of tests to a minimum, and
89 this sequence still causes to the same failure.
90 3. (XXX: todo): then it reruns the minimal sequence in the verbose
92 mode and saves the output.
93 4. It reports all the successful reductions as it goes to STDOUT and
95 report file of the format: smoke-report-<date>.txt.
96 In addition the systems build parameters are logged into the report
98 file, so the detected problems could be reproduced.
99 5. Goto 1 and run again using a new random seed, which potentially
101 should detect different failures.
102
104 Currently for each reduction path, the following reduction algorithms
105 get applied:
106 1. Binary search: first try the upper half then the lower.
108 2. Random window: randomize the left item, then the right item and
110 return the items between these two points.
111
113 t/SMOKE.PL is driving this module, if you don't have it, create it:
114 #!perl
116 use strict;
118 use warnings FATAL => 'all';
119 use FindBin;
121 use lib "$FindBin::Bin/../Apache-Test/lib";
122 use lib "$FindBin::Bin/../lib";
123 use Apache::TestSmoke ();
125 Apache::TestSmoke->new(@ARGV)->run;
127 usually Makefile.PL converts it into t/SMOKE while adjusting the perl
129 path, but you create t/SMOKE in first place as well.
130
132 Stas Bekman
133perl v5.34.0 2021-07-22 Apache::TestSmoke(3)