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Running and Developing Tests with the Apache::Test Framework | |
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Running and Developing Tests with the Apache::Test Framework | |
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The mod_perl Developer's Cookbook
By Geoffrey Young, Paul Lindner, Randy Kobes |
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mod_perl Pocket Reference
By Andrew Ford |
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Writing Apache Modules with Perl and C
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Embedding Perl in HTML with Mason
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The title is self-explanatory :)
The Apache::Test framework was designed for creating test suites for
products running on the Apache httpd webserver (not necessarily
mod_perl). Originally designed for the mod_perl Apache module, it was
extended to be used for any Apache module.
This chapter discusses the Apache-Test framework, and in
particular explains how to:
For other Apache::Test resources, see the References
section at the end of this document.
The tests themselves are written in Perl. The framework provides extensive functionality which makes writing tests a simple and therefore enjoyable process.
If you have ever written or looked at the tests that come with most Perl
modules, you'll recognize that Apache::Test uses the same
concepts. The script t/TEST executes all the files ending with
.t that it finds in the t/ directory. When executed, a typical test
prints the following:
1..3 # going to run 3 tests ok 1 # the first test has passed ok 2 # the second test has passed not ok 3 # the third test has failed
Every ok or not ok is followed by a number that identifies which
sub-test has passed or failed.
t/TEST uses the Test::Harness module, which intercepts the
STDOUT stream, parses it and at the end of the tests, prints the
results of the tests: how many tests and sub-tests were run and
how many passed, failed, or were skipped.
Some tests may be skipped by printing:
1..0 # all tests in this file are going to be skipped.
Usually a test may be skipped when some feature is optional and/or prerequisites are not installed on the system, but this is not critical for the usefulness of the test. Once you determine that you cannot proceed with the tests, and it is not a requirement that the tests pass, you can just skip them.
By default, print statements in the test script are filtered out by
Test::Harness. If you want the test to print what it does (for example,
to debug a test) use the -verbose option. So for example if
your test does this:
print "# testing : feature foo\n"; print "# expected: $expected\n"; print "# received: $received\n"; ok $expected eq $received;
in the normal mode, you won't see any of these prints. But if you run
the test with t/TEST -verbose, you will see something like this:
# testing : feature foo # expected: 2 # received: 2 ok 2
When you develop the test you should always insert the debug statements, and once the test works for you, do not comment out or delete these debug statements. It's a good idea to leave them in because if some user reports a failure in some test, you can ask him to run the failing test in the verbose mode and send you the report. It'll be much easier to understand the problem if you get these debug printings from the user.
A simpler approach is to use the Test::More module in your test
scripts. This module offers many useful test functions, including
diag, a function that automatically escapes and passes strings to
print to bypass Test::Harness:
use Test::More; diag "testing : feature foo\n"; diag "expected: $expected\n"; diag "received: $received\n"; ok $expected eq $received;
In fact, for an example such as this, you can just use Test::More's
is function, which will output the necessary diagnostics in the event
of a test failure:
is $received, $expected;
For which the output for a test failure would be something like:
not ok 1 # Failed test (-e at line 1) # got: '1' # expected: '2'
The Writing Tests section documents several helper functions that make simplify the writing of tests.
For more details about the Test::Harness module please refer to its
manpage. Also see the Test and Test::More manpages for
documentation of Perl's test suite.
In order to use Apache::Test it has to be installed first.
Install Apache::Test using the familiar procedure:
% cd Apache-Test % perl Makefile.PL % make && make test && make install
If you install mod_perl 2.0, Apache::Test will be installed with it.
It's much easier to copy existing examples than to create something from scratch. It's also simpler to develop tests when you have some existing system to test, so that you can see how it works and build your own testing environment in a similar fashion. So let's first look at how the existing test enviroments work.
You can look at the modperl-2.0's or httpd-test's (perl-framework)
testing environments, both of which use Apache::Test for their test
suites.
Run:
% t/TEST -help
to get a list of options you can use during testing. Most options are covered further in this document.
Running tests is just like for any CPAN Perl module; first we generate
the Makefile file and build everything with make:
% perl Makefile.PL [options] % make
Now we can do the testing. You can run the tests in two ways. The first one is the usual:
% make test
But this approach adds quite an overhead, since it has to check that
everything is up to date (the usual make source change control).
Therefore, you have to run it only once after make; for re-running
the tests, it's faster to run them directly via:
% t/TEST
When make test or t/TEST is run, all tests found in the t
directory (files ending with .t are recognized as tests) will be
run.
To run a single test, simply specify it at the command line. For example, to run the test file t/protocol/echo.t, execute:
% t/TEST protocol/echo
Notice that the t/ prefix and the .t extension for the test filenames are optional when you specify them explicitly. Therefore the following are all valid commands:
% t/TEST protocol/echo.t % t/TEST t/protocol/echo % t/TEST t/protocol/echo.t
The server will be stopped if it was already running and a new one will be started before running the t/protocol/echo.t test. At the end of the test the server will be shut down.
When you run specific tests you may want to run them in the verbose mode and, depending on how the tests were written, you may get more debugging information under this mode. Verbose mode is turned on with -verbose option:
% t/TEST -verbose protocol/echo
You can run groups of tests at once, too. This command:
% ./t/TEST modules protocol/echo
will run all the tests in t/modules/ directory, followed by t/protocol/echo.t test.
By default, when you run tests without the -run-tests option, the server will be started before the testing and stopped at the end. If during a debugging process you need to re-run tests without the need to restart the server, you can start it once:
% t/TEST -start-httpd
and then run the test(s) with -run-tests option many times:
% t/TEST -run-tests
without waiting for the server to restart.
When you are done with tests, stop the server with:
% t/TEST -stop-httpd
When the server is running, you can modify .t files and rerun the tests without restarting it. But if you modify response handlers, you must restart the server for changes to take an effect. However, if the changes are only to perl code, it's possible to arrange for Apache::Test to handle the code reload without restarting the server.
The -start-httpd option always stops the server first if any is running.
Normally, when t/TEST is run without specifying the tests to run, the tests will be sorted alphabetically. If tests are explicitly passed as arguments to t/TEST they will be run in the specified order.
Sometimes you need to run more than one Apache-Test framework
instance at the same time. In this case you have to use different
ports for each instance. You can specify explicitly which port to use
using the -port configuration option. For example, to run the server
on port 34343, do this:
% t/TEST -start-httpd -port=34343
You can also affect the port by setting the APACHE_TEST_PORT
evironment variable to the desired value before starting the server.
Specifying the port explicitly may not be the most convenient option
if you happen to run many instances of the Apache-Test framework.
The -port=select option helps such situations. This option will
automatically select the next available port. For example if you
run:
% t/TEST -start-httpd -port=select
and there is already one server from a different test suite which uses the default port 8529, the new server will try to use a higher port.
There is one problem that remains to be resolved, though. It's possible
that two or more servers running -port=select will still decide to
use the same port, because when the server is configured it only tests
whether the port is available but doesn't call bind() immediately. This
race condition needs to be resolved. Currently the workaround is to
start the instances of the Apache-Test framework with a slight delay
between them. Depending on the speed of your machine, 4-5 seconds can be
a good choice, as this is the approximate the time it takes to configure
and start the server on a quite slow machine.
In case something goes wrong you should run the tests in verbose mode:
% t/TEST -verbose
In verbose mode, the test may print useful information, like what values
it expects and what values it receives, given that the test is written
to report these. In silent mode (without -verbose), these printouts
are filtered out by Test::Harness. When running in verbose, mode
usually it's a good idea to run only problematic tests in order to
minimize the size of the generated output.
When debugging tests, it often helps to keep the error_log file open in another console, and see the debug output in the real time via tail(1):
% tail -f t/logs/error_log
Of course this file gets created only when the server starts, so you
cannot run tail(1) on it before the server starts. Every time t/TEST
-clean is run, t/logs/error_log gets deleted; therefore, you'll have
to run the tail(1) command again once the server starts.
If your terminal supports colored text you may want to set the
environment variable APACHE_TEST_COLOR to 1 to enable any colored
tracing when running in the non-batch mode. Colored tracing mode can
make it easier to discriminate errors and warnings from other
notifications.
In addition to controlling the verbosity of the test scripts, you can
control the amount of information printed by the Apache::Test
framework itself. Similar to Apache's log levels, Apache::Test uses
these levels for controlling its signal to noise ratio:
emerg alert crit error warning notice info debug
where emerg is the for the most important messages and debug is for the least important ones.
Currently, the default level is info; therefore, any messages which
fall into the info category and above (notice, warning, etc)
will be output. This tracing level is unrelated to Apache's LogLevel
mechanism, which Apache-Test sets to debug in t/conf/httpd.conf
and which you can override t/conf/extra.conf.in.
Let's assume you have the following code snippet:
use Apache::TestTrace; warning "careful, perl on the premises"; debug "that's just silly";
If you want to get only warning messages and above, use:
% t/TEST -trace=warning ...
now only the warning message
careful, perl on the premises
will be printed. If you want to see debug messages, you can
change the default level using -trace option:
% t/TEST -trace=debug ...
now the last example will print both messages.
By default the messages are printed to STDERR, but can be redirected
to a file. Refer to the Apache::TestTrace manpage for more
information.
Finally, you can use the emerg(), alert(), crit(), error(),
warning(), notice(), info() and debug() methods in your
client and server side code. These methods are useful when, for example,
you have some debug tracing that you don't want to be printed during the
normal make test or .Build test. However, if some users have a
problem you can ask them to run the test suite with the trace level set
to 'debug' and, voila, they can send you the extra debug output.
Moreover, all of these functions use Data::Dumper to dump arguments
that are references to perl structures. So for example your code may
look like:
use Apache::TestTrace;
...
my $data = { foo => bar };
debug "my data", $data;
and only when run with -trace=debug it'll output:
my data
$VAR1 = {
'foo' => 'bar'
};
Normally it will print nothing.
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 important to run random testing repeated many times with many different pseudo-random engine initialization seeds. Of course if no failures get spotted that doesn't mean that there are no tests inter-dependencies, unless all possible combinations were run (exhaustive approach). Therefore it's possible that some problems may still be seen in production, but this testing greatly minimizes such a possibility.
The Apache-Test framework provides a few options useful for stress
testing.
You can run the tests N times by using the -times option. For example to run all the tests 3 times specify:
% t/TEST -times=3
It's possible that certain tests aren't cleaning up after themselves and modify the state of the server, which may influence other tests. But since normally all the tests are run in the same order, the potential problem may not be discovered until the code is used in production, where the real world testing hits the problem. Therefore in order to try to detect as many problems as possible during the testing process, it's may be useful to run tests in different orders.
This is of course mostly useful in conjunction with -times=N option.
Assuming that we have tests a, b and c:
rotate the tests: a, b, c, a, b, c
repeat the tests: a, a, b, b, c, c
run in the random order, e.g.: a, c, c, b, a, b
In this mode the seed picked by srand() is printed to STDOUT, so it
then can be used to rerun the tests in exactly the same order
(remember to log the output).
used to initialize the pseudo-random algorithm, which allows to reproduce the same sequence of tests. For example if we run:
% t/TEST -order=random -times=5
and the seed 234559 is used, we can repeat the same order of tests, by running:
% t/TEST -order=234559 -times=5
Alternatively, the environment variable APACHE_TEST_SEED can be set
to the value of a seed when -order=random is used. e.g. under
bash(1):
% APACHE_TEST_SEED=234559 t/TEST -order=random -times=5
or with any shell program if you have the env(1) utility:
$ env APACHE_TEST_SEED=234559 t/TEST -order=random -times=5
When this kind of testing is used and a failure is detected there are two problems:
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 problem.
Apache::TestSmoke SolutionApache::TestSmoke attempts to solve both problems. When it's run,
at the end of each iteration it reports the minimal sequence of tests
causing a failure. This doesn't always succeed, but works in many
cases.
You should create a small script to drive Apache::TestSmoke,
usually t/SMOKE.PL. If you don't have it already, create it:
#file:t/SMOKE.PL #--------------- #!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 can create t/SMOKE in first place as well.
t/SMOKE performs the following operations:
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.
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 are applied:
Binary search: first try the upper half then the lower.
Random window: randomize the left item, then the right item and return the items between these two points.
You can get the usage information by executing:
% t/SMOKE -help
By default you don't need to supply any arguments to run it, simply execute:
% t/SMOKE
If you want to work on certain tests you can specify them in the same way you do with t/TEST:
% t/SMOKE foo/bar foo/tar
If you already have a sequence of tests that you want to reduce (perhaps because a previous run of the smoke testing didn't reduce the sequence enough to be able to diagnose the problem), you can request to do just that:
% t/SMOKE -order=rotate -times=1 foo/bar foo/tar
-order=rotate is used just to override the default -order=random, since in this case we want to preserve the order. We also specify -times=1 for the same reason (override the default which is 50).
You can override the number of srand() iterations to perform (read: how many times to randomize the sequence), the number of times to repeat the tests (the default is 10) and the path to the file to use for reports:
% t/SMOKE -times=5 -iterations=20 -report=../myreport.txt
Finally, any other options passed will be forwarded to t/TEST as
is.
After the server is configured during make test or with t/TEST
-config, it's possible to explicitly override certain configuration
parameters. The override-able parameters are listed when executing:
% t/TEST -help
Probably the most useful parameters are:
configuration directives to add at the beginning of httpd.conf. For example to turn the tracing on:
% t/TEST -preamble "PerlTrace all"
configuration directives to add at the end of httpd.conf. For example to load a certain Perl module:
% t/TEST -postamble "PerlModule MyDebugMode"
run as user nobody:
% t/TEST -user nobody
run on a different port:
% t/TEST -port 8799
run on a different server:
% t/TEST -servername test.example.com
configure an httpd other than the default (that apxs figures out):
% t/TEST -httpd ~/httpd-2.0/httpd
switch to another apxs:
% t/TEST -apxs ~/httpd-2.0-prefork/bin/apxs
For a complete list of override-able configuration parameters see the
output of t/TEST -help.
We have mentioned already the most useful run-time options. Here are some other options that you may find useful during testing.
Ping the server to see whether it runs
% t/TEST -ping
Ping the server and wait until the server starts, report waiting time.
% t/TEST -ping=block
This can be useful in conjunction with -run-tests option during debugging:
% t/TEST -ping=block -run-tests
normally, -run-tests will immediately quit if it detects that the server is not running, but with -ping=block in effect, it'll wait indefinitely for the server to start up.
Issue a HEAD request. For example to request /server-info:
% t/TEST -head /server-info
Request the body of a certain URL via GET.
% t/TEST -get /server-info
If no URL is specified / is used.
ALso you can issue a GET request but to get only headers as a
response (e.g. useful to just check Content-length)
% t/TEST -head -get /server-info
GET URL with authentication credentials:
% t/TEST -get /server-info -username dougm -password domination
(please keep the password secret!)
Generate a POST request.
Read content to POST from string:
% t/TEST -post /TestApache__post -content 'name=dougm&company=covalent'
Read content to POST from STDIN:
% t/TEST -post /TestApache__post -content - < foo.txt
Generate a content body of 1024 bytes in length:
% t/TEST -post /TestApache__post -content x1024
The same but print only the response headers, e.g. useful to just
check Content-length:
% t/TEST -post -head /TestApache__post -content x1024
Add headers to (-get|-post|-head) request:
% t/TEST -get -header X-Test=10 -header X-Host=example.com /server-info
Run all tests through mod_ssl:
% t/TEST -ssl
Run all tests with HTTP/1.1 (KeepAlive) requests:
% t/TEST -http11
Run all tests through mod_proxy:
% t/TEST -proxy
The debugging options -debug and -breakpoint are covered in the Debugging Tests section.
For a complete list of available switches see the output of t/TEST
-help.
When running in the batch mode and redirecting STDOUT, this state
is automagically detected and the no color mode is turned on, under
which the program generates a minimal output to make the log files
useful. If this doesn't work and you still get all the mess printed
during the interactive run, set the APACHE_TEST_NO_COLOR=1
environment variable.
We will assume that you have setup your testing environment even before you have started coding the project, which is a very smart thing to do. Of course it'll take you more time upfront, but it'll will save you a lot of time during the project developing and debugging stages. The extreme programming methodology says that tests should be written before starting the code development.
In the following demonstration and mostly through the whole document we assume that the test suite is written for a module running under mod_perl 2.0. You may need to adjust the code and the configuration files to the mod_perl 1.0 syntax, if you work with that generation of mod_perl. If your test suite needs to work with both mod_perl generations refer to the porting to mod_perl 2.0 chapter. Of course it's quite possible that what you test doesn't have mod_perl at all, in which case, again, you will need to make adjustments to work in the given environment.
So the first thing is to create a package and all the helper files, so
later we can distribute it on CPAN. We are going to develop an
Apache::Amazing module as an example.
% h2xs -AXn Apache::Amazing Writing Apache/Amazing/Amazing.pm Writing Apache/Amazing/Makefile.PL Writing Apache/Amazing/README Writing Apache/Amazing/test.pl Writing Apache/Amazing/Changes Writing Apache/Amazing/MANIFEST
h2xs is a nifty utility that gets installed together with Perl and
helps us to create some of the files we will need later.
However, we are going to use a slightly different file layout; therefore we are going to move things around a bit.
We want our module to live in the Apache-Amazing directory, so we do:
% mv Apache/Amazing Apache-Amazing % rmdir Apache
From now on the Apache-Amazing directory is our working directory.
% cd Apache-Amazing
We don't need the test.pl, as we are going to create a whole testing environment:
% rm test.pl
We want our package to reside under the lib directory, so later we
will be able to do live testing, without rerunning make every time
we change the code:
% mkdir lib % mkdir lib/Apache % mv Amazing.pm lib/Apache
Now we adjust lib/Apache/Amazing.pm to look like this:
#file:lib/Apache/Amazing.pm
#--------------------------
package Apache::Amazing;
use strict;
use warnings;
use Apache2::RequestRec ();
use Apache2::RequestIO ();
$Apache::Amazing::VERSION = '0.01';
use Apache2::Const -compile => 'OK';
sub handler {
my $r = shift;
$r->content_type('text/plain');
$r->print("Amazing!");
return Apache::OK;
}
1;
__END__
... pod documentation goes here...
The only thing our modules does is set the text/plain header and respond with "Amazing!".
Next, you have a choice to make. Perl modules typically use one of two
build systems: ExtUtils::MakeMaker or Module::Build.
ExtUtils::MakeMaker is the traditional Perl module build system, and
comes preinstalled with Perl. It generates a tradiational Makefile to
handle the build process. The code to generate the Makefile resides
in Makefile.PL.
Module::Build is a new build system, available from CPAN, and
scheduled to be added to the core Perl distribution in version 5.10,
with the goal of eventually replacing
ExtUtils::MakeMaker. Module::Build uses pure Perl code to manage
the build process, making it much easier to override its behavior to
perform special build tasks. It is also more portable, since it relies
on Perl itself, rather than the make utility.
So the decision you need to make is which system to use. Most modules on
CPAN use ExtUtils::MakeMaker, and for most simple modules it is more
than adequate. But more and more modules are moving to Module::Build
so as to take advantage of its new features. Module::Build is the
future of Perl build systems, but ExtUtils::MakeMaker is likely to be
around for some time to come.
Fortunately, Apache::Test makes it easy to use either build system.
ExtUtils::MakeMaker
If you decide to use ExtUtils::MakeMaker, adjust or create the
Makefile.PL file to use Apache::TestMM:
#file:Makefile.PL
#----------------
require 5.6.1;
use ExtUtils::MakeMaker;
use lib qw(../blib/lib lib );
use Apache::TestMM qw(test clean); #enable 'make test'
# prerequisites
my %require =
(
"Apache::Test" => "", # any version will do
);
my @scripts = qw(t/TEST);
# accept the configs from command line
Apache::TestMM::filter_args();
Apache::TestMM::generate_script('t/TEST');
WriteMakefile(
NAME => 'Apache::Amazing',
VERSION_FROM => 'lib/Apache/Amazing.pm',
PREREQ_PM => \%require,
clean => {
FILES => "@{ clean_files() }",
},
($] >= 5.005 ?
(ABSTRACT_FROM => 'lib/Apache/Amazing.pm',
AUTHOR => 'Stas Bekman <stas (at) stason.org>',
) : ()
),
);
sub clean_files {
return [@scripts];
}
Apache::TestMM does a lot of thing for us, such as building a
complete Makefile with proper 'test' and 'clean' targets,
automatically converting .PL and conf/*.in files and more.
As you can see, we specify a prerequisites hash that includes
Apache::Test, so if the package gets distributed on CPAN, the
CPAN.pm and CPANPLUS shells will know to fetch and install this
required package.
Module::Build
If you decide to use Module::Build, the process is even simpler. Just
delete the Makefile.PL file and create Build.PL instead. It should
look somethiing like this:
use Module::Build:
my $build_pkg = eval { require Apache::TestMB }
? 'Apache::TestMB' : 'Module::Build';
my $build = $build_pkg->new(
module_name => 'Apache::Amazing',
license => 'perl',
build_requires => { Apache::Test => '1.12' },
create_makefile_pl => 'passthrough',
);
$build->create_build_script;
Note that the first thing this script does is check to be sure that
Apache::TestMB is installed. If it is not, and your module is
installed with the CPAN.pm or CPANPLUS shells, it will be
installed before continuing. This is because we've specified that
Apache::Test 1.12 (the first version of Apache::Test to include
Apache::TestMB) is required to build the module (in this case,
because its tests require it). We've also specified what license the
module is distributed under, and that a passthrough Makefile.PL
should be generated. This last parameter helps those who don't have
Module::Build installed, as it allows them to use an
ExtUtils::MakeMaker-style Makefile.PL script to build, test, and
install the module (although what the passthrough script actually does
is install Module::Build from CPAN and pass build commands through to
our Build.PL script).
Next we create the test suite, which will reside in the t directory:
% mkdir t
First we create t/TEST.PL which will be automatically converted
into t/TEST during perl Makefile.PL stage:
#file:t/TEST.PL #-------------- #!perl use strict; use warnings FATAL => 'all'; use lib qw(lib); use Apache::TestRunPerl (); Apache::TestRunPerl->new->run(@ARGV);
This script assumes that Apache::Test is already installed on your
system and that Perl can find it. If not, you should tell Perl where to
find it. For example you could add:
use lib qw(Apache-Test/lib);
to t/TEST.PL, if Apache::Test is located in a parallel
directory.
As you can see we didn't write the real path to the Perl executable,
but #!perl. When t/TEST is created the correct path will be
placed there automatically.
Note: If you use Apache::TestMB in a Build.PL script, the
creation of the t/TEST.PL script is optional. You only need to create
it if you need it to do something special that the above example does
not.
Next we need to prepare extra Apache configuration bits, which will reside in t/conf:
% mkdir t/conf
We create the t/conf/extra.conf.in file, which will be automatically
converted into t/conf/extra.conf before the server starts. If the
file has any placeholders like @documentroot@, these will be replaced
with the real values specific for the Apache server used for the
tests. In our case, we put the following configuration bits into this
file:
#file:t/conf/extra.conf.in
#-------------------------
# this file will be Include-d by @ServerRoot@/conf/httpd.conf
# where Apache::Amazing can be found
PerlSwitches -I@ServerRoot@/../lib
# preload the module
PerlModule Apache::Amazing
<Location /test/amazing>
SetHandler modperl
PerlResponseHandler Apache::Amazing
</Location>
As you can see, we just add a simple <Location> container and
tell Apache that the namespace /test/amazing should be handled by
the Apache::Amazing module running as a mod_perl handler. Notice
that:
SetHandler modperl
is mod_perl 2.0 configuration, if you are running under mod_perl 1.0 use:
SetHandler perl-script
which also works for mod_perl 2.0.
Now we can create a simple test:
#file:t/basic.t
#-----------
use strict;
use warnings FATAL => 'all';
use Apache::Amazing;
use Apache::Test;
use Apache::TestUtil;
use Apache::TestRequest 'GET_BODY';
plan tests => 2;
ok 1; # simple load test
my $url = '/test/amazing';
my $data = GET_BODY $url;
ok t_cmp(
$data,
"Amazing!",
"basic test",
);
Now create the README file.
% touch README
Don't forget to put in the relevant information about your module, or
arrange for ExtUtils::MakeMaker::WriteMakefile() to do this for you
with:
#file:Makefile.PL
#----------------
WriteMakefile(
#...
dist => {
PREOP => 'pod2text lib/Apache/Amazing.pm > $(DISTVNAME)/README',
},
#...
);
Or for Module::Build to generate the README with:
#file:Build.PL
#-------------
my $build = $build_pkg->new(
#...
create_readme => 1,
#...
);
In these cases, README will be created from the documenation POD
sections in lib/Apache/Amazing.pm, but the file must exist for
make dist or ./Build.PL dist to succeed.
And finally, we adjust or create the MANIFEST file, so we can prepare a complete distribution. Therefore we list all the files that should enter the distribution including the MANIFEST file itself:
#file:MANIFEST #------------- lib/Apache/Amazing.pm t/TEST.PL t/basic.t t/conf/extra.conf.in Makefile.PL # and/or Build.PL Changes README MANIFEST
You can automate the creation or updating of the MANIFEST file using
make manifest with Makefile.PL or ./Build manifest with
Build.PL.
That's it. Now we can build the package. But we need to know the
location of the apxs utility from the installed httpd server. We
pass its path as an option to Makefile.PL or Build.PL. To build,
test, and install the module with Makefile.PL, do this:
% perl Makefile.PL -apxs ~/httpd/prefork/bin/apxs % make % make test basic...........ok All tests successful. Files=1, Tests=2, 1 wallclock secs ( 0.52 cusr + 0.02 csys = 0.54 CPU)
To install the package run:
% make install
Now we are ready to distribute the package on CPAN:
% make dist
This build command will create the package which can be immediately uploaded to CPAN. In this example, the generated source package with all the required files will be called: Apache-Amazing-0.01.tar.gz.
The same process can be accomplished with Buiild.PL like so:
# perl Build.PL -apxs ~/httpd/prefork/bin/apxs % ./Build % ./Build test basic...........ok All tests successful. Files=1, Tests=2, 1 wallclock secs ( 0.52 cusr + 0.02 csys = 0.54 CPU) % ./Build install % ./Build dist
The only thing that we haven't done and hope that you will do is to
write the POD sections for the Apache::Amazing module, explaining
how amazingly it works and how amazingly it can be deployed by other
users.
Sometimes you need to add extra httpd.conf configuration and perl
startup-specific code to your project that uses Apache::Test. This
can be accomplished by creating the desired files with an extension
.in in the t/conf/ directory and running:
panic% t/TEST -config
which for each file with the extension .in will create a new file, without this extension, convert any template placeholders into real values and link it from the main httpd.conf. The latter happens only if the file have the following extensions:
will add to t/conf/httpd.conf:
Include foo.conf
will add to t/conf/httpd.conf:
PerlRequire foo.pl
other files with .in extension will be processed as well, but not linked from httpd.conf.
Files whose name matches the following pattern:
/\.last\.(conf|pl).in$/
will be included very last in httpd.conf. This is especially useful
if you want to include Apache directives that would need a running Perl
interpreter (see When Does perl Start To Run)
without conflicting with Apache::Test's use of
PerlSwitches.
Make sure that you don't try to create httpd.conf.in, it is not going to work, since httpd.conf is already generated by Apache-Test.
As mentioned before the converted files are created, any special tokens
in them are getting replaced with the appropriate values. For example
the token @ServerRoot@ will be replaced with the value defined by
the ServerRoot directive, so you can write a file that does the
following:
#file:my-extra.conf.in #--------------------- PerlSwitches -I@ServerRoot@/../lib
and assuming that the ServerRoot is ~/modperl-2.0/t/, when my-extra.conf will be created, it'll look like:
#file:my-extra.conf #------------------ PerlSwitches -I~/modperl-2.0/t/../lib
The valid tokens are defined in %Apache::TestConfig::Usage and also
can be seen in the output of t/TEST -help's configuration
options section. The tokens are case insensitive.
For a complete list see the Apache::TestConfig manpage.
Some of the files in the t/conf directory have a special meaning,
since the Apache-Test framework uses them for the minimal
configuration setup. But they can be overriden:
if the file t/conf/httpd.conf.in exists, it will be used instead of the default template (in Apache/TestConfig.pm).
if the file t/conf/extra.conf.in exists, it will be used to
generate t/conf/extra.conf with @variable@ substitutions.
if the file t/conf/extra.last.conf.in exists, it will be used to
generate t/conf/extra.last.conf with @variable@ substitutions.
if the file t/conf/extra.conf exists, it will be included by httpd.conf.
if the file t/conf/extra.last.conf exists, it will be included by httpd.conf after the t/conf/extra.conf file.
if the file t/conf/modperl_extra.pl exists, it will be included by httpd.conf as a mod_perl file (PerlRequire).
Apache::Test tries to find a global httpd.conf file and inherit
its configuration when autogenerating t/conf/httpd.conf. For
example it picks LoadModule directives.
It's possible to explicitly specify which file to inherit from using
the -httpd_conf option. For example during the build:
% perl Makefile.PL -httpd_conf /path/to/httpd.conf
or with Build.PL:
% perl Build.PL -httpd_conf /path/to/httpd.conf
or during the configuration:
% t/TEST -conf -httpd_conf /path/to/httpd.conf
Certain projects need to have a control of what gets inherited. For example if your global httpd.conf includes a directive:
LoadModule apreq_module "/home/joe/apache2/modules/mod_apreq.so"
And you want to run the test suite for Apache::Request 2.0,
inheriting the above directive will load the pre-installed
mod_apreq.so and not the newly built one, which is wrong. In such
cases it's possible to tell the test suite which modules shouldn't be
inherited. In our example Apache-Request has the following code
in t/TEST.PL:
use base 'Apache::TestRun';
$Apache::TestTrace::Level = 'debug';
main::->new->run(@ARGV);
sub pre_configure {
my $self = shift;
# Don't load an installed mod_apreq
Apache::TestConfig::autoconfig_skip_module_add('mod_apreq.c');
}
it subclasses Apache::TestRun and overrides the pre_configure
method, which excludes the module mod_apreq.c from the list of
inherited modules (notice that the extension is .c).
In the previous section we have written a basic test, which doesn't do much. In the following sections we will explain how to write more elaborate tests.
When you write the test for Apache, unless you want to test some static resource, like fetching a file, usually you have to write a response handler and the corresponding test that will generate a request which will exercise this response handler and verify that the response is as expected. From now we may call these two parts as client and server parts of the test, or request and response parts of the test.
In some cases the response part of the test runs the test inside
itself, so all it requires from the request part of the test, is to
generate the request and print out a complete response without doing
anything else. In such cases Apache::Test can auto-generate the
client part of the test for you.
If you write only a response part of the test, Apache::Test will
automatically generate the corresponding test part that will generated
the response. In this case your test should print 'ok 1', 'not ok
2' responses as usual tests do. The autogenerated request part will
receive the response and print them out automatically completing the
Test::Harness expectations.
The corresponding request part of the test is named just like the response part, using the following translation:
(my $tmp = $path) =~ s{t/[^/]+/(.*).pm}{$1.t};
my $client_file = catfile 't',
map { s/^test//i; lc $_ } split '::', $tmp;
Notice that the leading /^test/ part is removed. Here are some
examples of that translation:
t/response/MyApache/write.pm => t/myapache/write.t t/response/TestApache/write.pm => t/apache/write.t t/response/TestApache/Mar/write.pm => t/apache/mar/write.t
If we look at the autogenerated test t/apache/write.t, we can see
that it starts with the warning that it has been autogenerated, so you
won't attempt to change it. Then you can see the trace of the calls
that generated this test, in case you want to figure out how the test
was generated. And finally the test loads the Apache::TestRequest
module, imports the GET shortcut and prints the response's body if
it was successful. Otherwise it dies to flag the problem with the
server side. The latter is done because there is nothing on the client
side, that tells the testing framework that things went wrong. Without
it the test will be skipped, and that's not what we want.
use Apache::TestRequest 'GET_BODY_ASSERT'; print GET_BODY_ASSERT "/TestApache__write";
As you can see the request URI is autogenerated from the response test name:
$response_test =~ s|.*/([^/]+)/(.*).pm$|/$1__$2|;
So t/response/TestApache/write.pm becomes: /TestApache__write.
Now a simple response test may look like this:
#file:t/response/TestApache/write.pm
#-----------------------------------
package TestApache::write;
use strict;
use warnings FATAL => 'all';
use constant BUFSIZ => 512; #small for testing
use Apache2::Const -compile => 'OK';
sub handler {
my $r = shift;
$r->content_type('text/plain');
$r->write("1..2\n");
$r->write("ok 1")
$r->write("not ok 2")
Apache2::Const::OK;
}
1;
[F] Apache2::Const is mod_perl 2.0's package, if you test under 1.0,
use the Apache::Constants module instead [/F].
The configuration part for this test will be autogenerated by the
Apache-Test framework and added to the autogenerated file
t/conf/httpd.conf when make test or ./Build test or t/TEST
-configure is run. In our case the following configuration section will
be added:
<Location /TestApache__write>
SetHandler modperl
PerlResponseHandler TestApache::write
</Location>
You should remember to run:
% t/TEST -configure
so the configuration file will be re-generated when new tests are added.
Also notice that if you manually add configuration the
<Location> path can't include ':' characters in the
first segment, due to Apache security protection on WinFU
platforms. So please make sure that you don't create entries like:
<Location /Foo::bar/>
You can include ':' characters in the further segments, so this is
OK:
<Location /tests/Foo::bar/>
Of course if your code is not intended to run on WinFU you can ignore this detail.
But in most cases you want to write a two parts test where the client (request) parts generates various requests and tests the responses.
It's possible that the client part tests a static file or some other feature that doesn't require a dynamic response. In this case, only the request part of the test should be written.
If you need to write the complete test, with two parts, you proceed just like in the previous section, but now you write the client part of the test by yourself. It's quite easy, all you have to do is to generate requests and check the response. So a typical test will look like this:
#file:t/apache/cool.t
#--------------------
use strict;
use warnings FATAL => 'all';
use Apache::Test;
use Apache::TestUtil;
use Apache::TestRequest 'GET_BODY';
plan tests => 1; # plan one test.
Apache::TestRequest::module('default');
my $config = Apache::Test::config();
my $hostport = Apache::TestRequest::hostport($config) || '';
t_debug("connecting to $hostport");
my $received = GET_BODY "/TestApache__cool";
my $expected = "COOL";
ok t_cmp(
$received,
$expected,
"testing TestApache::cool",
);
See the Apache::TestUtil manpage for more info on the t_cmp()
function (e.g. it works with regexs as well).
And the corresponding response part:
#file:t/response/TestApache/cool.pm
#----------------------------------
package TestApache::cool;
use strict;
use warnings FATAL => 'all';
use Apache2::Const -compile => 'OK';
sub handler {
my $r = shift;
$r->content_type('text/plain');
$r->write("COOL");
Apache2::Const::OK;
}
1;
Again, remember to run t/TEST -clean before running the new test so the configuration will be created for it.
As you can see the test generates a request to /TestApache__cool, and expects it to return "COOL". If we run the test:
% ./t/TEST t/apache/cool
We see:
apache/cool....ok All tests successful. Files=1, Tests=1, 1 wallclock secs ( 0.52 cusr + 0.02 csys = 0.54 CPU)
But if we run it in the debug (verbose) mode, we can actually see what we are testing, what was expected and what was received:
apache/cool....1..1 # connecting to localhost:8529 # testing : testing TestApache::cool # expected: COOL # received: COOL ok 1 ok All tests successful. Files=1, Tests=1, 1 wallclock secs ( 0.49 cusr + 0.03 csys = 0.52 CPU)
So in case in our simple test we have received something different from COOL or nothing at all, we can immediately see what's the problem.
The name of the request part of the test is very important. If
Apache::Test cannot find the corresponding test for the response
part it'll automatically generate one and in this case it's probably
not what you want. Therefore when you choose the filename for the
test, make sure to pick the same Apache::Test will pick. So if the
response part is named: t/response/TestApache/cool.pm the request
part should be named t/apache/cool.t. See the regular expression
that does that in the previous section.
If you need to exercise some C API and you don't have a Perl glue for
it, you can still use Apache::Test for the testing. It allows you
to write response handlers in C and makes it easy to integrate these
with other Perl tests and use Perl for request part which will
exercise the C module.
The C modules look just like standard Apache C modules, with a couple of differences to:
The httpd-test ASF project is a good example to look at. The C
modules are located under: httpd-test/perl-framework/c-modules/.
Look at c-modules/echo_post/echo_post.c for a nice simple example.
mod_echo_post simply echos data that is POSTed to it.
The differences between vairous tests may be summarized as follows:
If the first line is:
#define HTTPD_TEST_REQUIRE_APACHE 1
or
#define HTTPD_TEST_REQUIRE_APACHE 2
then the test will be skipped unless the version matches. If a module
is compatible with the version of Apache used then it will be
automatically compiled by t/TEST with -DAPACHE1 or -DAPACHE2
so you can conditionally compile it to suit different httpd versions.
In additon to the single-digit form,
#define HTTPD_TEST_REQUIRE_APACHE 2.0.48
and
#define HTTPD_TEST_REQUIRE_APACHE 2.1
are also supported, allowing for conditional compilation based on criteria similar to have_min_apache_version().
If there is a section bounded by:
#if CONFIG_FOR_HTTPD_TEST ... #endif
in the .c file then that section will be inserted verbatim into t/conf/httpd.conf by t/TEST.
There is a certain amount of magic which hopefully allows most modules to be compiled for Apache 1.3 or Apache 2.0 without any conditional stuff. Replace XXX with the module name, for example echo_post or random_chunk:
You should:
#include "apache_httpd_test.h"
which should be preceded by an:
#define APACHE_HTTPD_TEST_HANDLER XXX_handler
apache_httpd_test.h pulls in a lot of required includes and defines some constants and types that are not defined for Apache 1.3.
The handler function should be:
static int XXX_handler(request_rec *r);
At the end of the file should be an:
APACHE_HTTPD_TEST_MODULE(XXX)
where XXX is the same as that in APACHE_HTTPD_TEST_HANDLER. This
will generate the hooks and stuff.
If you have LWP (libwww-perl) installed its LWP::UserAgent serves
as an user agent in tests, otherwise Apache::TestClient tries to
emulate partial LWP functionality. So most of the LWP documentation
applies here, but the Apache-Test framework provides shortcuts
that hide many details, making the test writing a simple and swift
task. Before using these shortcuts Apache::TestRequest should be
loaded, and its import() method will fetch the shortcuts into the
caller namespace:
use Apache::TestRequest;
Request generation methods issue a request and return a response
object (HTTP::Response if LWP is available). They are documented in
the HTTP::Request::Common manpage. The following methods are
available:
Issues the GET request. For example, issue a request and retrieve
the response content:
$url = "$location?foo=1&bar=2"; $res = GET $url; $str = $res->content;
To set request headers, supply them after the $url, e.g.:
$res = GET $url, 'Content-type' => 'text/html';
Issues the HEAD request. For example issue a request and check that
the response's Content-type is text/plain:
$url = "$location?foo=1&bar=2"; $res = HEAD $url; ok $res->content_type() eq 'text/plain';
Issues the POST request. For example:
$content = 'PARAM=%33'; $res = POST $location, content => $content;
The second argument to POST can be a reference to an array or a
hash with key/value pairs to emulate HTML <form> POSTing.
Issues the PUT request.
META: ???
These are two special methods added by the Apache-Test framework:
This special method allows to upload a file or a string which will look as an uploaded file to the server. To upload a file use:
UPLOAD $location, filename => $filename;
You can add extra request headers as well:
UPLOAD $location, filename => $filename, 'X-Header-Test' => 'Test';
This function sends the form data in a POST response.
To insert additional parameters, append them as 'key' => 'value' elements as in the following example (notice that an additional file upload was made via the my_file_name parameter):
UPLOAD $location, filename => $filename, my_file_name => ['Test.txt'],
username => 'Captain Kirk', password => 'beam me up';
To upload a string as a file, use:
UPLOAD $location, content => 'some data';
Retrieves the content from the response resulted from doing
UPLOAD. It's equal to:
my $body = UPLOAD(@_)->content;
For example, this code retrieves the content of the response resulted from file upload request:
my $str = UPLOAD_BODY $location, filename => $filename;
Once the response object is returned, various response object methods can be applied to it. Probably the most useful ones are:
$content = $res->content;
to retrieve the content fo the respose and:
$content_type = $res->header('Content-type');
to retrieve specific headers.
Refer to the HTTP::Response manpage for a complete reference of
these and other methods.
A few response retrieval shortcuts can be used to retrieve the wanted parts of the response. To apply these simply add the shortcut name to one of the request shortcuts listed earlier. For example instead of retrieving the content part of the response via:
$res = GET $url; $str = $res->content;
simply use:
$str = GET_BODY $url;
returns the response code, equivalent to:
$res->code;
For example to test whether some URL is bogus:
use Apache::Const 'NOT_FOUND';
ok GET_RC('/bogus_url') == NOT_FOUND;
You usually need to import and use Apache::Const constants for the
response code comparisons, rather then using codes' corresponding
numerical values directly. You can import groups of code as well. For
example:
use Apache::Const ':common';
Refer to the Apache::Const manpage for a complete reference. Also
you may need to use APR and mod_perl constants, which reside in
APR::Const and ModPerl::Const modules respectively.
tests whether the response was successful, equivalent to:
$res->is_success;
For example:
ok GET_OK '/foo';
returns the response (both, headers and body) as a string and is equivalent to:
$res->as_string;
Mostly useful for debugging, for example:
use Apache::TestUtil; t_debug POST_STR '/test.pl', content => 'foo';
returns the headers part of the response as a multi-line string.
For example, this code dumps all the response headers:
use Apache::TestUtil; t_debug GET_HEAD '/index.html';
returns the response body and is equivalent to:
$res->content;
For example, this code validates that the response's body is the one that was expected:
use Apache::TestUtil;
ok GET_BODY('/index.html') eq $expect;
Same as the BODY shortcut, but will assert if the request has
failed. So for example if the test's output is generated on the server
side, the client side may only need to print out what the server has
sent and we want it to report that the test has failed if the request
has failed:
use Apache::TestUtil; print GET_BODY_ASSERT "/foo"
META: these methods need documentation
Request part:
Apache::TestRequest::scheme('http'); #force http for t/TEST -ssl
Apache::TestRequest::module($module);
my $config = Apache::Test::config();
my $hostport = Apache::TestRequest::hostport($config);
Getting the request object? Apache::TestRequest::user_agent()
By default the Apache-Test framework sets up only a single server
to test against.
In some cases you need to have more than one server. If this is the
situation, you have to override the maxclients configuration
directive, whose default is 1. Usually this is done in t/TEST.PL by
subclassing the parent test run class and overriding the
new_test_config() method. For example if the parent class is
Apache::TestRunPerl, you can change your t/TEST.PL to be:
use strict;
use warnings FATAL => 'all';
use lib "../lib"; # test against the source lib for easier dev
use lib map {("../blib/$_", "../../blib/$_")} qw(lib arch);
use Apache::TestRunPerl ();
package MyTest;
our @ISA = qw(Apache::TestRunPerl);
# subclass new_test_config to add some config vars which will be
# replaced in generated httpd.conf
sub new_test_config {
my $self = shift;
$self->{conf_opts}->{maxclients} = 2;
return $self->SUPER::new_test_config;
}
MyTest->new->run(@ARGV);
By default the Apache-Test framework uses a single user agent
which talks to the server (this is the LWP user agent, if you have
LWP installed). You almost never use this agent directly in the
tests, but via various wrappers. However if you need a second user
agent you can clone these. For example:
my $ua2 = Apache::TestRequest::user_agent()->clone;
When a single instance of the server thread/process is running, all
the tests go through the same server. However if the Apache::Test
framework was configured to to run a few instances, two subsequent
sub-tests may not hit the same server instance. In certain tests
(e.g. testing the closure effect or the BEGIN blocks) it's
important to make sure that a sequence of sub-tests are run against
the same server instance. The Apache-Test framework supports this
internally.
Here is an example from ModPerl::Registry closure tests. Using the
counter closure problem under ModPerl::Registry:
#file:cgi-bin/closure.pl
#-----------------------
#!perl -w
print "Content-type: text/plain\r\n\r\n";
# this is a closure (when compiled inside handler()):
my $counter = 0;
counter();
sub counter {
#warn "$$";
print ++$counter;
}
If this script get invoked twice in a row and we make sure that it gets executed by the same server instance, the first time it'll return 1 and the second time 2. So here is the gist of the request part that makes sure that its two subsequent requests hit the same server instance:
#file:closure.t
#--------------
...
my $url = "/same_interp/cgi-bin/closure.pl";
my $same_interp = Apache::TestRequest::same_interp_tie($url);
# should be no closure effect, always returns 1
my $first = req($same_interp, $url);
my $second = req($same_interp, $url);
ok t_cmp(
$first && $second && ($second - $first),
1,
"the closure problem is there",
);
sub req {
my ($same_interp, $url) = @_;
my $res = Apache::TestRequest::same_interp_do($same_interp,
\&GET, $url);
return $res ? $res->content : undef;
}
In this test we generate two requests to cgi-bin/closure.pl and
expect the returned value to increment for each new request, because
of the closure problem generated by ModPerl::Registry. Since we
don't know whether some other test has called this script already, we
simply check whether the substraction of the two subsequent requests'
outputs gives a value of 1.
The test starts by requesting the server to tie a single instance to all requests made with a certain identifier. This is done using the same_interp_tie() function which returns a unique server instance's indentifier. From now on any requests made through same_interp_do() and supplying this indentifier as the first argument will be served by the same server instance. The second argument to same_interp_do() is the method to use for generating the request and the third is the URL to use. Extra arguments can be supplied if needed by the request generation method (e.g. headers).
This technique works for testing purposes where we know that we have
just a few server instances. What happens internally is when
same_interp_tie() is called the server instance that served it returns
its unique UUID, so when we want to hit the same server instance in
subsequent requests we generate the same request until we learn that
we are being served by the server instance that we want. This magic is
done by using a fixup handler which returns OK only if it sees that
its unique id matches. As you understand this technique would be very
inefficient in production with many server instances.
All the communications between tests and Test::Harness which
executes them is done via STDOUT. I.e. whatever tests want to report
they do by printing something to STDOUT. If a test wants to print some
debug comment it should do it starting on a separate line, and each
debug line should start with #. The t_debug() function from the
Apache::TestUtil package should be used for that purpose.
Before sub-tests of a certain test can be run it has to declare how many sub-tests it is going to run. In some cases the test may decide to skip some of its sub-tests or not to run any at all. Therefore the first thing the test has to print is:
1..M\n
where M is a positive integer. So if the test plans to run 5 sub-tests it should do:
print "1..5\n";
In Apache::Test this is done as follows:
use Apache::Test; plan tests => 5;
Sometimes when the test cannot be run, because certain prerequisites
are missing. To tell Test::Harness that the whole test is to be
skipped do:
print "1..0 # skipped because of foo is missing\n";
The optional comment after # skipped will be used as a reason for
test's skipping. Under Apache::Test the optional last argument to
the plan() function can be used to define prerequisites and skip the
test:
use Apache::Test; plan tests => 5, $test_skipping_prerequisites;
This last argument can be:
SCALAR
the test is skipped if the scalar has a false value. For example:
plan tests => 5, 0;
But this won't hint the reason for skipping therefore it's better to
use have():
plan tests => 5,
have 'LWP',
{ "not Win32" => sub { $^O eq 'MSWin32'} };
ARRAY reference
have_module() is called for each value in this array. The test is skipped if have_module() returns false (which happens when at least one C or Perl module from the list cannot be found). For example:
plan tests => 5, [qw(mod_index mod_mime)];
CODE reference
the tests will be skipped if the function returns a false value. For example:
plan tests => 5, \&have_lwp;
the test will be skipped if LWP is not available
There is a number of useful functions whose return value can be used as a last argument