Warn(3) User Contributed Perl Documentation Warn(3)NAMETest::Warn - Perl extension to test methods for warnings
SYNOPSIS
use Test::Warn;
warning_is {foo(-dri => "/")} "Unknown Parameter 'dri'", "dri != dir gives warning";
warnings_are {bar(1,1)} ["Width very small", "Height very small"];
warning_is {add(2,2)} undef, "No warning to calc 2+2"; # or
warnings_are {add(2,2)} [], "No warning to calc 2+2"; # what reads better :-)
warning_like {foo(-dri => "/")} qr/unknown param/i, "an unknown parameter test";
warnings_like {bar(1,1)} [qr/width.*small/i, qr/height.*small/i];
warning_is {foo()} {carped => "didn't found the right parameters"};
warnings_like {foo()} [qr/undefined/,qr/undefined/,{carped => qr/no result/i}];
warning_like {foo(undef)} 'uninitialized';
warning_like {bar(file => '/etc/passwd')} 'io';
warning_like {eval q/"$x"; $x;/}
[qw/void uninitialized/],
"some warnings at compile time";
DESCRIPTION
This module provides a few convenience methods for testing warning
based code.
If you are not already familiar with the Test::More manpage now would
be the time to go take a look.
FUNCTIONS
warning_is BLOCK STRING, TEST_NAME
Tests that BLOCK gives exactly the one specificated warning. The
test fails if the BLOCK warns more then one times or doesn't warn.
If the string is undef, then the tests succeeds iff the BLOCK
doesn't give any warning. Another way to say that there aren't ary
warnings in the block, is "warnings_are {foo()} [], "no warnings
in"".
If you want to test for a warning given by carp, You have to write
something like: "warning_is {carp "msg"} {carped => 'msg'}, "Test
for a carped warning"". The test will fail, if a "normal" warning
is found instead of a "carped" one.
Note: "warn "foo"" would print something like "foo at -e line 1".
This method ignores everything after the at. That means, to match
this warning you would have to call "warning_is {warn "foo"} "foo",
"Foo succeeded"". If you need to test for a warning at an exactly
line, try better something like "warning_like {warn "foo"} qr/at
XYZ.dat line 5/".
warning_is and warning_are are only aliases to the same method. So
you also could write "warning_is {foo()} [], "no warning"" or some‐
thing similar. I decided me to give two methods to have some bet‐
ter readable method names.
A true value is returned if the test succeeds, false otherwise.
The test name is optional, but recommended.
warnings_are BLOCK ARRAYREF, TEST_NAME
Tests to see that BLOCK gives exactly the specificated warnings.
The test fails if the BLOCK warns a different number than the size
of the ARRAYREf would have expected. If the ARRAYREF is equal to
[], then the test succeeds iff the BLOCK doesn't give any warning.
Please read also the notes to warning_is as these methods are only
aliases.
If you want more than one tests for carped warnings look that way:
"warnings_are {carp "c1"; carp "c2"} {carped =" ['c1','c2'];> or
"warnings_are {foo()} ["Warning 1", {carped =" ["Carp 1", "Carp
2"]}, "Warning 2"]>. Note that "{carped =" ...}> has always to be
a hash ref.
warning_like BLOCK REGEXP, TEST_NAME
Tests that BLOCK gives exactly one warning and it can be matched to
the given regexp. If the string is undef, then the tests succeeds
iff the BLOCK doesn't give any warning.
The REGEXP is matched after the whole warn line, which consists in
general of "WARNING at __FILE__ line __LINE__". So you can check
for a warning in at File Foo.pm line 5 with "warning_like {bar()}
qr/at Foo.pm line 5/, "Testname"". I don't know whether it's sens‐
ful to do such a test :-( However, you should be prepared as a
matching with 'at', 'file', '\d' or similar will always pass.
Think to the qr/^foo/ if you want to test for warning "foo some‐
thing" in file foo.pl.
You can also write the regexp in a string as "/.../" instead of
using the qr/.../ syntax. Note that the slashes are important in
the string, as strings without slashes are reserved for warning
categories (to match warning categories as can be seen in the per‐
llexwarn man page).
Similar to "warning_is", you can test for warnings via "carp" with:
"warning_like {bar()} {carped =" qr/bar called too early/i};>
Similar to "warning_is"/"warnings_are", "warning_like" and "warn‐
ings_like" are only aliases to the same methods.
A true value is returned if the test succeeds, false otherwise.
The test name is optional, but recommended.
warning_like BLOCK STRING, TEST_NAME
Tests whether a BLOCK gives exactly one warning of the passed cate‐
gory. The categories are grouped in a tree, like it is expressed
in perllexwarn. Note, that they have the hierarchical structure
from perl 5.8.0, wich has a little bit changed to 5.6.1 or earlier
versions (You can access the internal used tree with
$Test::Warn::Categorization::tree, allthough I wouldn't recommend
it)
Thanks to the grouping in a tree, it's simple possible to test for
an 'io' warning, instead for testing for a 'closed⎪exec⎪layer⎪new‐
line⎪pipe⎪unopened' warning.
Note, that warnings occuring at compile time, can only be catched
in an eval block. So
warning_like {eval q/"$x"; $x;/}
[qw/void uninitialized/],
"some warnings at compile time";
will work, while it wouldn't work without the eval.
Note, that it isn't possible yet, to test for own categories, cre‐
ated with warnings::register.
warnings_like BLOCK ARRAYREF, TEST_NAME
Tests to see that BLOCK gives exactly the number of the specifi‐
cated warnings and all the warnings have to match in the defined
order to the passed regexes.
Please read also the notes to warning_like as these methods are
only aliases.
Similar to "warnings_are", you can test for multiple warnings via
"carp" and for warning categories, too:
warnings_like {foo()}
[qr/bar warning/,
qr/bar warning/,
{carped => qr/bar warning/i},
'io'
],
"I hope, you'll never have to write a test for so many warnings :-)";
EXPORT
"warning_is", "warnings_are", "warning_like", "warnings_like" by
default.
BUGS
Please note that warnings with newlines inside are making a lot of
trouble. The only sensful way to handle them is to use are the "warn‐
ing_like" or "warnings_like" methods. Background for these problems is
that there is no really secure way to distinguish between warnings with
newlines and a tracing stacktrace.
If a method has it's own warn handler, overwriting $SIG{__WARN__}, my
test warning methods won't get these warnings.
The "warning_like BLOCK CATEGORY, TEST_NAME" method isn't extremely
tested. Please use this calling style with higher attention and tell
me if you find a bug.
TODO
Improve this documentation.
The code has some parts doubled - especially in the test scripts. This
is really awkward and has to be changed.
Please feel free to suggest me any improvements.
SEE ALSO
Have a look to the similar Test::Exception module. Test::Trap
THANKS
Many thanks to Adrian Howard, chromatic and Michael G. Schwern, who
have given me a lot of ideas.
AUTHOR
Janek Schleicher, <bigj AT kamelfreund.de>
COPYRIGHT AND LICENSE
Copyright 2002 by Janek Schleicher
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.8.8 2008-07-09 Warn(3)
