Test::Exception(3) User Contributed Perl Documentation Test::Exception(3)NAMETest::Exception - Test exception based code
SYNOPSIS
use Test::More tests => 5;
use Test::Exception;
# or if you don't need Test::More
use Test::Exception tests => 5;
# then...
# Check that the stringified exception matches given regex
throws_ok { $foo->method } qr/division by zero/, 'zero caught okay';
# Check an exception of the given class (or subclass) is thrown
throws_ok { $foo->method } 'Error::Simple', 'simple error thrown';
# all Test::Exceptions subroutines are guaranteed to preserve the state
# of $@ so you can do things like this after throws_ok and dies_ok
like $@, 'what the stringified exception should look like';
# Check that something died - we do not care why
dies_ok { $foo->method } 'expecting to die';
# Check that something did not die
lives_ok { $foo->method } 'expecting to live';
# Check that a test runs without an exception
lives_and { is $foo->method, 42 } 'method is 42';
# or if you don't like prototyped functions
throws_ok( sub { $foo->method }, qr/division by zero/,
'zero caught okay' );
throws_ok( sub { $foo->method }, 'Error::Simple',
'simple error thrown' );
dies_ok( sub { $foo->method }, 'expecting to die' );
lives_ok( sub { $foo->method }, 'expecting to live' );
lives_and( sub { is $foo->method, 42 }, 'method is 42' );
DESCRIPTION
This module provides a few convenience methods for testing exception
based code. It is built with Test::Builder and plays happily with
Test::More and friends.
If you are not already familiar with Test::More now would be the time
to go take a look.
You can specify the test plan when you "use Test::Exception" in the
same way as "use Test::More". See Test::More for details.
NOTE: Test::Exception only checks for exceptions. It will ignore other
methods of stopping program execution - including exit(). If you have
an exit() in evalled code Test::Exception will not catch this with any
of its testing functions.
throws_ok
Tests to see that a specific exception is thrown. throws_ok() has
two forms:
throws_ok BLOCK REGEX, TEST_DESCRIPTION
throws_ok BLOCK CLASS, TEST_DESCRIPTION
In the first form the test passes if the stringified exception
matches the give regular expression. For example:
throws_ok { read_file( 'unreadable' ) } qr/No file/, 'no file';
If your perl does not support "qr//" you can also pass a regex-like
string, for example:
throws_ok { read_file( 'unreadable' ) } '/No file/', 'no file';
The second form of throws_ok() test passes if the exception is of
the same class as the one supplied, or a subclass of that class.
For example:
throws_ok { $foo->bar } "Error::Simple", 'simple error';
Will only pass if the "bar" method throws an Error::Simple excep‐
tion, or a subclass of an Error::Simple exception.
You can get the same effect by passing an instance of the exception
you want to look for. The following is equivalent to the previous
example:
my $SIMPLE = Error::Simple->new;
throws_ok { $foo->bar } $SIMPLE, 'simple error';
Should a throws_ok() test fail it produces appropriate diagnostic
messages. For example:
not ok 3 - simple error
# Failed test (test.t at line 48)
# expecting: Error::Simple exception
# found: normal exit
Like all other Test::Exception functions you can avoid prototypes
by passing a subroutine explicitly:
throws_ok( sub {$foo->bar}, "Error::Simple", 'simple error' );
A true value is returned if the test succeeds, false otherwise. On
exit $@ is guaranteed to be the cause of death (if any).
A description of the exception being checked is used if no optional
test description is passed.
dies_ok
Checks that a piece of code dies, rather than returning normally.
For example:
sub div {
my ( $a, $b ) = @_;
return $a / $b;
};
dies_ok { div( 1, 0 ) } 'divide by zero detected';
# or if you don't like prototypes
dies_ok( sub { div( 1, 0 ) }, 'divide by zero detected' );
A true value is returned if the test succeeds, false otherwise. On
exit $@ is guaranteed to be the cause of death (if any).
Remember: This test will pass if the code dies for any reason. If
you care about the reason it might be more sensible to write a more
specific test using throws_ok().
The test description is optional, but recommended.
lives_ok
Checks that a piece of code doesn't die. This allows your test
script to continue, rather than aborting if you get an unexpected
exception. For example:
sub read_file {
my $file = shift;
local $/;
open my $fh, '<', $file or die "open failed ($!)\n";
$file = <FILE>;
return $file;
};
my $file;
lives_ok { $file = read_file('test.txt') } 'file read';
# or if you don't like prototypes
lives_ok( sub { $file = read_file('test.txt') }, 'file read' );
Should a lives_ok() test fail it produces appropriate diagnostic
messages. For example:
not ok 1 - file read
# Failed test (test.t at line 15)
# died: open failed (No such file or directory)
A true value is returned if the test succeeds, false otherwise. On
exit $@ is guaranteed to be the cause of death (if any).
The test description is optional, but recommended.
lives_and
Run a test that may throw an exception. For example, instead of
doing:
my $file;
lives_ok { $file = read_file('answer.txt') } 'read_file worked';
is $file, "42", 'answer was 42';
You can use lives_and() like this:
lives_and { is read_file('answer.txt'), "42" } 'answer is 42';
# or if you don't like prototypes
lives_and(sub {is read_file('answer.txt'), "42"}, 'answer is 42');
Which is the same as doing
is read_file('answer.txt'), "42\n", 'answer is 42';
unless "read_file('answer.txt')" dies, in which case you get the
same kind of error as lives_ok()
not ok 1 - answer is 42
# Failed test (test.t at line 15)
# died: open failed (No such file or directory)
A true value is returned if the test succeeds, false otherwise. On
exit $@ is guaranteed to be the cause of death (if any).
The test description is optional, but recommended.
SKIPPING TEST::EXCEPTION TESTS
Sometimes we want to use Test::Exception tests in a test suite, but
don't want to force the user to have Test::Exception installed. One way
to do this is to skip the tests if Test::Exception is absent. You can
do this with code something like this:
use strict;
use warnings;
use Test::More;
BEGIN {
eval "use Test::Exception";
plan skip_all => "Test::Exception needed" if $@;
}
plan tests => 2;
# ... tests that need Test::Exception ...
Note that we load Test::Exception in a "BEGIN" block ensuring that the
subroutine prototypes are in place before the rest of the test script
is compiled.
BUGS
There are some edge cases in Perl's exception handling where
Test::Exception will miss exceptions thrown in DESTROY blocks. See the
RT bug <http://rt.cpan.org/Ticket/Display.html?id=24678> for details,
along with the t/edge-cases.t in the distribution test suite. These
will be addressed in a future Test::Exception release.
If you find any more bugs please let me know by e-mail, or report the
problem with <http://rt.cpan.org/>.
COMMUNITY
perl-qa
If you are interested in testing using Perl I recommend you visit
<http://qa.perl.org/> and join the excellent perl-qa mailing list.
See <http://lists.perl.org/showlist.cgi?name=perl-qa> for details
on how to subscribe.
perlmonks
You can find users of Test::Exception, including the module author,
on <http://www.perlmonks.org/>. Feel free to ask questions on
Test::Exception there.
CPAN::Forum
The CPAN Forum is a web forum for discussing Perl's CPAN modules.
The Test::Exception forum can be found at <http://www.cpanfo‐
rum.com/dist/Test-Exception>.
AnnoCPAN
AnnoCPAN is a web site that allows community annotations of Perl
module documentation. The Test::Exception annotations can be found
at <http://annocpan.org/~ADIE/Test-Exception/>.
TO DO
If you think this module should do something that it doesn't (or does
something that it shouldn't) please let me know.
You can see my current to do list at <http://adrianh.tadal‐
ist.com/lists/public/15421>, with an RSS feed of changes at
<http://adrianh.tadalist.com/lists/feed_public/15421>.
ACKNOWLEDGMENTS
Thanks to chromatic and Michael G Schwern for the excellent
Test::Builder, without which this module wouldn't be possible.
Thanks to Adam Kennedy, Andy Lester, Aristotle Pagaltzis, Ben Prew,
Cees Hek, Chris Dolan, chromatic, Curt Sampson, David Cantrell, David
Golden, David Wheeler, Janek Schleicher, Jim Keenan, Jos I. Boumans,
Joshua ben Jore, Jost Krieger, Mark Fowler, Michael G Schwern, Nadim
Khemir, Paul McCann, Perrin Harkins, Peter Scott, Rob Muhlestein Scott
R. Godin, Steve Purkis, Steve, Tim Bunce, and various anonymous folk
for comments, suggestions, bug reports and patches.
AUTHOR
Adrian Howard <adrianh@quietstars.com>
If you can spare the time, please drop me a line if you find this mod‐
ule useful.
SEE ALSO
<http://del.icio.us/tag/Test::Exception>
Delicious links on Test::Exception.
Test::Warn & Test::NoWarnings
Modules to help test warnings.
Test::Builder
Support module for building test libraries.
Test::Simple & Test::More
Basic utilities for writing tests.
<http://qa.perl.org/test-modules.html>
Overview of some of the many testing modules available on CPAN.
<http://del.icio.us/tag/perl+testing>
Delicious links on perl testing.
LICENCE
Copyright 2002-2007 Adrian Howard, All Rights Reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.8.8 2008-02-17 Test::Exception(3)
