1Test::NoWarnings(3)   User Contributed Perl Documentation  Test::NoWarnings(3)
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NAME

6       Test::NoWarnings - Make sure you didn't emit any warnings while testing
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SYNOPSIS

9       For scripts that have no plan
10
11         use Test::More 'no_plan';
12         use Test::NoWarnings;
13
14       that's it, you don't need to do anything else
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16       For scripts that look like
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18         use Test::More tests => x;
19
20       change to
21
22         use Test::More tests => x + 1;
23         use Test::NoWarnings;
24
25       For scripts that use done_testing, use:
26
27         use Test::More;
28         use Test::NoWarnings 'had_no_warnings';
29
30         ... # your actual tests
31
32         had_no_warnings;
33         done_testing;
34

DESCRIPTION

36       In general, your tests shouldn't produce warnings. This modules causes
37       any warnings to be captured and stored. It automatically adds an extra
38       test that will run when your script ends to check that there were no
39       warnings. If there were any warnings, the test will give a "not ok" and
40       diagnostics of where, when and what the warning was, including a stack
41       trace of what was going on when the it occurred.
42
43       If some of your tests are supposed to produce warnings then you should
44       be capturing and checking them with Test::Warn, that way
45       Test::NoWarnings will not see them and so not complain.
46
47       The test is run by an "END" block in Test::NoWarnings. It will not be
48       run when any forked children exit.
49

USAGE

51       Simply by using the module, you automatically get an extra test at the
52       end of your script that checks that no warnings were emitted. So just
53       stick
54
55         use Test::NoWarnings;
56
57       at the top of your script and continue as normal.
58
59       If you want more control you can invoke the test manually at any time
60       with "had_no_warnings".
61
62       The warnings your test has generated so far are stored in an array. You
63       can look inside and clear this whenever you want with "warnings()" and
64       "clear_warnings", however, if you are doing this sort of thing then you
65       probably want to use Test::Warn in combination with Test::NoWarnings.
66
67       If you have a test script written using done_testing and no test plan,
68       you have to call "had_no_warnings" before you call done_testing.
69
70   use vs require
71       You will almost always want to do
72
73         use Test::NoWarnings;
74
75       If you do a "require" rather than a "use", then there will be no
76       automatic test at the end of your script.
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78   Output
79       If warning is captured during your test then the details will output as
80       part of the diagnostics. You will get:
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82       • the number and name of the test that was executed just before the
83         warning (if no test had been executed these will be 0 and '')
84
85       • the message passed to "warn",
86
87       • a full dump of the stack when warn was called, courtesy of the "Carp"
88         module
89
90       By default, all warning messages will be emitted in one block at the
91       end of your test script.
92
93   The :early pragma
94       One common complaint from people using Test::NoWarnings is that all of
95       the warnings are emitted in one go at the end. While this is the safest
96       and most correct time to emit these diagnostics, it can make debugging
97       these warnings difficult.
98
99       As of Test::NoWarnings 1.04 you can provide an experimental ":early"
100       pragma when loading the module to force warnings to be thrown via diag
101       at the time that they actually occur.
102
103         use Test::NoWarnings ':early';
104
105       As this will cause the diag to be emitted against the previous test and
106       not the one in which the warning actually occurred it is recommended
107       that the pragma be turned on only for debugging and left off when not
108       needed.
109

FUNCTIONS

111   had_no_warnings
112       This checks that there have been warnings emitted by your test scripts.
113       Usually you will not call this explicitly as it is called automatically
114       when your script finishes.
115
116   clear_warnings
117       This will clear the array of warnings that have been captured. If the
118       array is empty then a call to "had_no_warnings()" will produce a pass
119       result.
120
121   warnings
122       This will return the array of warnings captured so far. Each element of
123       this array is an object containing information about the warning. The
124       following methods are available on these object.
125
126       • $warn->getMessage
127
128         Get the message that would been printed by the warning.
129
130       • $warn->getCarp
131
132         Get a stack trace of what was going on when the warning happened,
133         this stack trace is just a string generated by the Carp module.
134
135       • $warn->getTrace
136
137         Get a stack trace object generated by the Devel::StackTrace module.
138         This will return undef if Devel::StackTrace is not installed.
139
140       • $warn->getTest
141
142         Get the number of the test that executed before the warning was
143         emitted.
144
145       • $warn->getTestName
146
147         Get the name of the test that executed before the warning was
148         emitted.
149

PITFALLS

151       When counting your tests for the plan, don't forget to include the test
152       that runs automatically when your script ends.
153
154       Checking for warnings is done using $SIG{__WARN__}.  If other modules
155       use this hook, it can interfere with this module's operation.  For
156       example, using the Carp::Always module will cause this module to always
157       report no warnings.
158

SUPPORT

160       Bugs should be reported via the CPAN bug tracker at
161
162       <https://rt.cpan.org/Ticket/Create.html?Queue=Test-NoWarnings>
163
164       For other issues, contact the author.
165

HISTORY

167       This was previously known as Test::Warn::None
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SEE ALSO

170       Test::Builder, Test::Warn
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AUTHORS

173       Fergal Daly <fergal@esatclear.ie>
174
175       Adam Kennedy <adamk@cpan.org>
176
178       Copyright 2003 - 2007 Fergal Daly.
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180       Some parts copyright 2010 - 2011 Adam Kennedy.
181
182       This program is free software and comes with no warranty. It is
183       distributed under the LGPL license
184
185       See the file LICENSE included in this distribution or
186       http://www.fsf.org/licenses/licenses.html.
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189
190perl v5.34.0                      2021-08-03               Test::NoWarnings(3)
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