1Warn(3) User Contributed Perl Documentation Warn(3)
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6 Test::Warn - Perl extension to test methods for warnings
7
9 use Test::Warn;
10 warning_is {foo(-dri => "/")} "Unknown Parameter 'dri'", "dri != dir gives warning";
12 warnings_are {bar(1,1)} ["Width very small", "Height very small"];
13 warning_is {add(2,2)} undef, "No warnings for calc 2+2"; # or
15 warnings_are {add(2,2)} [], "No warnings for calc 2+2"; # what reads better :-)
16 warning_like {foo(-dri => "/")} qr/unknown param/i, "an unknown parameter test";
18 warnings_like {bar(1,1)} [qr/width.*small/i, qr/height.*small/i];
19 warning_is {foo()} {carped => "didn't find the right parameters"};
21 warnings_like {foo()} [qr/undefined/,qr/undefined/,{carped => qr/no result/i}];
22 warning_like {foo(undef)} 'uninitialized';
24 warning_like {bar(file => '/etc/passwd')} 'io';
25 warning_like {eval q/"$x"; $x;/}
27 [qw/void uninitialized/],
28 "some warnings at compile time";
29 warnings_exist {...} [qr/expected warning/], "Expected warning is thrown";
31
33 A good style of Perl programming calls for a lot of diverse regression
34 tests.
35 This module provides a few convenience methods for testing warning
37 based code.
38 If you are not already familiar with the Test::More manpage now would
40 be the time to go take a look.
41 FUNCTIONS
43 warning_is BLOCK STRING, TEST_NAME
44 Tests that BLOCK gives the specified warning exactly once. The
45 test fails if the BLOCK warns more than once or does not warn at
46 all. If the string is undef, then the tests succeeds if the BLOCK
47 doesn't give any warning. Another way to say that there are no
48 warnings in the block is "warnings_are {foo()} [], "no warnings"".
49 If you want to test for a warning given by Carp, you have to write
51 something like: "warning_is {carp "msg"} {carped => 'msg'}, "Test
52 for a carped warning"". The test will fail if a "normal" warning
53 is found instead of a "carped" one.
54 Note: "warn "foo"" would print something like "foo at -e line 1".
56 This method ignores everything after the "at". Thus to match this
57 warning you would have to call "warning_is {warn "foo"} "foo", "Foo
58 succeeded"". If you need to test for a warning at an exactly line,
59 try something like "warning_like {warn "foo"} qr/at XYZ.dat line
60 5/".
61 warning_is and warning_are are only aliases to the same method. So
63 you also could write "warning_is {foo()} [], "no warning"" or
64 something similar. I decided to give two methods the same name to
65 improve readability.
66 A true value is returned if the test succeeds, false otherwise.
68 The test name is optional, but recommended.
70 warnings_are BLOCK ARRAYREF, TEST_NAME
72 Tests to see that BLOCK gives exactly the specified warnings. The
73 test fails if the warnings from BLOCK are not exactly the ones in
74 ARRAYREF. If the ARRAYREF is equal to [], then the test succeeds
75 if the BLOCK doesn't give any warning.
76 Please read also the notes to warning_is as these methods are only
78 aliases.
79 If you want more than one test for carped warnings, try this:
81 "warnings_are {carp "c1"; carp "c2"} {carped =" ['c1','c2'];> or
82 "warnings_are {foo()} ["Warning 1", {carped =" ["Carp 1", "Carp
83 2"]}, "Warning 2"]>. Note that "{carped =" ...}> must always be a
84 hash ref.
85 warning_like BLOCK REGEXP, TEST_NAME
87 Tests that BLOCK gives exactly one warning and it can be matched by
88 the given regexp. If the string is undef, then the tests succeeds
89 if the BLOCK doesn't give any warning.
90 The REGEXP is matched against the whole warning line, which in
92 general has the form "WARNING at __FILE__ line __LINE__". So you
93 can check for a warning in the file Foo.pm on line 5 with
94 "warning_like {bar()} qr/at Foo.pm line 5/, "Testname"". I don't
95 know whether it's sensful to do such a test :-( However, you should
96 be prepared as a matching with 'at', 'file', '\d' or similar will
97 always pass. Think to the qr/^foo/ if you want to test for warning
98 "foo something" in file foo.pl.
99 You can also write the regexp in a string as "/.../" instead of
101 using the qr/.../ syntax. Note that the slashes are important in
102 the string, as strings without slashes are reserved for warning
103 categories (to match warning categories as can be seen in the
104 perllexwarn man page).
105 Similar to "warning_is", you can test for warnings via "carp" with:
107 "warning_like {bar()} {carped =" qr/bar called too early/i};>
108 Similar to "warning_is"/"warnings_are", "warning_like" and
110 "warnings_like" are only aliases to the same methods.
111 A true value is returned if the test succeeds, false otherwise.
113 The test name is optional, but recommended.
115 warning_like BLOCK STRING, TEST_NAME
117 Tests whether a BLOCK gives exactly one warning of the passed
118 category. The categories are grouped in a tree, like it is
119 expressed in perllexwarn. Note, that they have the hierarchical
120 structure from perl 5.8.0, wich has a little bit changed to 5.6.1
121 or earlier versions (You can access the internal used tree with
122 $Test::Warn::Categorization::tree, although I wouldn't recommend
123 it)
124 Thanks to the grouping in a tree, it's simple possible to test for
126 an 'io' warning, instead for testing for a
127 'closed|exec|layer|newline|pipe|unopened' warning.
128 Note, that warnings occuring at compile time, can only be catched
130 in an eval block. So
131 warning_like {eval q/"$x"; $x;/}
133 [qw/void uninitialized/],
134 "some warnings at compile time";
135 will work, while it wouldn't work without the eval.
137 Note, that it isn't possible yet, to test for own categories,
139 created with warnings::register.
140 warnings_like BLOCK ARRAYREF, TEST_NAME
142 Tests to see that BLOCK gives exactly the number of the specified
143 warnings and all the warnings have to match in the defined order to
144 the passed regexes.
145 Please read also the notes to warning_like as these methods are
147 only aliases.
148 Similar to "warnings_are", you can test for multiple warnings via
150 "carp" and for warning categories, too:
151 warnings_like {foo()}
153 [qr/bar warning/,
154 qr/bar warning/,
155 {carped => qr/bar warning/i},
156 'io'
157 ],
158 "I hope, you'll never have to write a test for so many warnings :-)";
159 warnings_exist BLOCK STRING|ARRAYREF, TEST_NAME
161 Same as warning_like, but will warn() all warnings that do not
162 match the supplied regex/category, instead of registering an error.
163 Use this test when you just want to make sure that specific
164 warnings were generated, and couldn't care less if other warnings
165 happened in the same block of code.
166 warnings_exist {...} [qr/expected warning/], "Expected warning is thrown";
168 warnings_exist {...} ['uninitialized'], "Expected warning is thrown";
170 EXPORT
172 "warning_is", "warnings_are", "warning_like", "warnings_like",
173 "warnings_exist" by default.
174
176 Please note that warnings with newlines inside are making a lot of
177 trouble. The only sensible way to handle them is to use are the
178 "warning_like" or "warnings_like" methods. Background for these
179 problems is that there is no really secure way to distinguish between
180 warnings with newlines and a tracing stacktrace.
181 If a method has it's own warn handler, overwriting $SIG{__WARN__}, my
183 test warning methods won't get these warnings.
184 The "warning_like BLOCK CATEGORY, TEST_NAME" method isn't extremely
186 tested. Please use this calling style with higher attention and tell
187 me if you find a bug.
188
190 Improve this documentation.
191 The code has some parts doubled - especially in the test scripts. This
193 is really awkward and must be changed.
194 Please feel free to suggest improvements.
196
198 Have a look to the similar modules: Test::Exception, Test::Trap.
199
201 Many thanks to Adrian Howard, chromatic and Michael G. Schwern, who
202 have given me a lot of ideas.
203
205 Janek Schleicher, <bigj AT kamelfreund.de>
206
208 Copyright 2002 by Janek Schleicher
209 Copyright 2007-2011 by Alexandr Ciornii, <http://chorny.net/>
211 This library is free software; you can redistribute it and/or modify it
213 under the same terms as Perl itself.
214perl v5.16.3 2012-04-01 Warn(3)