Warn(3) User Contributed Perl Documentation Warn(3)
NAME
Test::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 something similar. I decided me to
give two methods to have some better 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 warn-
ing.
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 sensful 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 something" in file foo.pl.
You can also write the regexp in a string as "/.../" instead of using the qr/.../ syn-
tax. 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
perllexwarn 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 "warnings_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 category. The cate-
gories 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
$Test::Warn::Categorization::tree, allthough I wouldn't recommend it)
Thanks to the grouping in a tree, it's simple possible to test for an 'io' warning,
instead for testing for a 'closed|exec|layer|newline|pipe|unopened' warning.
Note, that warnings occuring at compile time, can only be catched in an eval block. So
warning_like {eval q/"$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, created with warn-
ings::register.
warnings_like BLOCK ARRAYREF, TEST_NAME
Tests to see that BLOCK gives exactly the number of the specificated 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 warn-
ing 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 "warning_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.
THANKS
Many thanks to Adrian Howard, chromatic and Michael G. Schwern, who have given me a lot of
ideas.
AUTHOR
Janek Schleicher,
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 2007-04-30 Warn(3)
|