NAME

       Test::Log::Log4perl - test log4perl

SYNOPSIS

         # setup l4p
         use Log::Log4Perl;
         # do your normal Log::Log4Perl setup here
         use Test::Log::Log4perl;

         # get the loggers
         my $logger  = Log::Log4perl->get_logger("Foo::Bar");
         my $tlogger = Test::Log::Log4perl->get_logger("Foo::Bar");

         # test l4p
         Test::Log::Log4perl->start();

         # declare we're going to log something
         $tlogger->error("This is a test");

         # log that something
         $logger->error("This is a test");

         # test that those things matched
         Test::Log::Log4perl->end("Test that that logs okay");

         # we also have a simplified version:
         {
           my $foo = Test::Log::Log4perl->expect(['foo.bar.quux', warn => qr/hello/ ]);
           # ... do something that should log 'hello'
         }
         # $foo goes out of scope; this triggers the test.

DESCRIPTION

       This module can be used to test that you're logging the right thing with Log::Log4perl.
       It checks that we get what, and only what, we expect logged by your code.

       The basic process is very simple.  Within your test script you get one or more loggers
       from Test::Log::Log4perl with the "get_logger" method just like you would with
       Log::Log4perl.  You're going to use these loggers to declare what you think the code
       you're going to test should be logging.

         # declare a bunch of test loggers
         my $tlogger = Test::Log::Log4perl->get_logger("Foo::Bar");

       Then, for each test you want to do you need to start up the module.

         # start the test
         Test::Log::Log4perl->start();

       This diverts all subsequent attempts Log::Log4perl makes to log stuff and records them
       internally rather than passing them though to the Log4perl appenders as normal.

       You then need to declare with the loggers we created earlier what we hope Log4perl will be
       asked to log.  This is the same syntax as Test::Log::Log4perl uses, except if you want you
       can use regular expressions:

         $tlogger->debug("fish");
         $tlogger->warn(qr/bar/);

       You then need to run your code that you're testing.

         # call some code that hopefully will call the log4perl methods
         # 'debug' with "fish" and 'warn' with something that contains 'bar'
         some_code();

       We finally need to tell Test::Log4Perl that we're done and it should do the comparisons.

         # start the test
         Test::Log::Log4perl->end("test name");

   Methods
       get_logger($category)
           Returns a new instance of Test::Log::Log4perl that can be used to log expected
           messages in the category passed.

       Test::Log::Log4perl->expect(%start_args, ['dotted.path', 'warn' => qr(this), 'warn' =>
       qr(that)], ..)
           Class convenience method. Used like this:

             { # start local scope
               my $foo = Test::Log::Log4perl->expect(['foo.bar.quux', warn => qr/hello/ ]);
               # ... do something that should log 'hello'
             } # $foo goes out of scope; this triggers the test.

       start
           Class method.  Start logging.  When you call this method it temporarily redirects all
           logging from the standard logging locations to the internal logging routine until end
           is called.  Takes parameters to change the behavior of this (and only this) test.  See
           below.

       debug(@what)
       info(@what)
       warn(@what)
       error(@what)
       fatal(@what)
           Instance methods.  String of things that you're expecting to log, at the level you're
           expecting them, in what class.

       end()
       end($name)
           Ends the test and compares what we've got with what we expected.  Switches logging
           back from being captured to going to wherever it was originally directed in the
           config.

   Ignoring All Logging Messages
       Sometimes you're going to be testing something that generates a load of spurious log
       messages that you simply want to ignore without testing their contents, but you don't want
       to have to reconfigure your log file.  The simplest way to do this is to do:

         use Test::Log::Log4perl;
         Test::Log::Log4perl->suppress_logging;

       All logging functions stop working.  Do not alter the Logging classes (for example, by
       changing the config file and use Log4perl's "init_and_watch" functionality) after this
       call has been made.

       This function will be effectively a no-op if the environmental variable
       "NO_SUPPRESS_LOGGING" is set to a true value (so if your code is behaving weirdly you can
       turn all the logging back on from the command line without changing any of the code)

   Selectively Ignoring Logging Messages By Priority
       It's a bad idea to completely ignore all messages.  What you probably want to do is ignore
       some of the trivial messages that you don't care about, and just test that there aren't
       any unexpected messages of a set priority.

       You can temporarily ignore any logging messages that are made by passing parameters to the
       "start" routine

         # for this test, just ignore DEBUG, INFO, and WARN
         Test::Log::Log4perl->start( ignore_priority => "warn" );

         # you can use the levels constants to do the same thing
         use Log::Log4perl qw(:levels);
         Test::Log::Log4perl->start( ignore_priority => $WARN );

       You might want to ignore all logging events at all (this can be used as quick way to not
       test the actual log messages, but just ignore the output.

         # for this test, ignore everything
         Test::Log::Log4perl->start( ignore_priority => "everything" );

         # contary to readability, the same thing (try not to write this)
         use Log::Log4perl qw(:levels);
         Test::Log::Log4perl->start( ignore_priority => $OFF );

       Or you might want to not ignore anything (which is the default, unless you've played with
       the method calls mentioned below:)

         # for this test, ignore nothing
         Test::Log::Log4perl->start( ignore_priority => "nothing" );

         # contary to readability, the same thing (try not to write this)
         use Log::Log4perl qw(:levels);
         Test::Log::Log4perl->start( ignore_priority => $ALL );

       You can also permanently effect what things are ignored with the "ignore_priority" method
       call.  This persists between tests and isn't automatically reset after each call to
       "start".

         # ignore DEBUG, INFO and WARN for all future tests
         Test::Log::Log4perl->ignore_priority("warn");

         # you can use the levels constants to do the same thing
         use Log::Log4perl qw(:levels);
         Test::Log::Log4perl->ignore_priority($WARN);

         # ignore everything (no log messages will be logged)
         Test::Log::Log4perl->ignore_priority("everything");

         # ignore nothing (messages will be logged reguardless of priority)
         Test::Log::Log4perl->ignore_priority("nothing");

       Obviously, you may temporarily override whatever permanent.

BUGS

       Logging methods don't return the number of appenders they've written to (or rather, they
       do, as it's always zero.)

       Changing the config file (if you're watching it) while this is testing / suppressing
       everything will probably break everything.  As will creating new appenders, etc...

AUTHOR

         Chia-liang Kao <clkao@clkao.org>
         Mark Fowler <mark@twoshortplanks.com>

COPYRIGHT

         Copyright 2010 Chia-liang Kao all rights reserved.
         Copyright 2005 Fotango Ltd all rights reserved.

         Licensed under the same terms as Perl itself.