Test::S...arnings(3)

✨ Test::Stream::Plugin::Warnings ✨

okay bestie, so this is a page from the User Contributed Perl Documentation collection, and it's all about Test::Stream::Plugin::Warnings 💖 — the lil plugin that gives you simple tools for testing code that may generate warnings. no cap, that's the whole NAME vibe.

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💀 DEPRECATED 💀

ngl this one's giving "we need to talk." This distribution is deprecated in favor of Test2, Test2::Suite, and Test2::Workflow. 🫶

There's a whole conversion guide waiting for you at Test::Stream::Manual::ToTest2 — go read it, it's the main character of your migration arc. 🌈

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🌸 SYNOPSIS 🌸

# Load the Warnings plugin, and Core cause we need that as well.
use Test::Stream qw/Core Warnings/;

# Returns undef if there are no warnings.
ok(!warns { ... }, "Codeblock did not warn");

is_deeply(
    warns { warn "foo\n"; warn "bar\n" },
    [
        "foo\n",
        "bar\n",
    ],
    "Got expected warnings"
);

# Dies if there are 0 warnings, or 2+ warnings, otherwise returns the 1 warning.
like( warning { warn 'xxx' }, qr/xxx/, "Got expected warning");

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🎀 EXPORTS 🎀

• $warnings = warns { ... } — bestie, if the codeblock issues any warnings, they get captured and handed back to you in an arrayref. 💅 If there were no warnings this returns undef. And here's the tea: you can be sure this will always be undef, or an arrayref with 1 or more warnings. no in-between, it's not messy like that.

# Returns undef if there are no warnings.
ok(!warns { ... }, "Codeblock did not warn");

is_deeply(
    warns { warn "foo\n"; warn "bar\n" },
    [
        "foo\n",
        "bar\n",
    ],
    "Got expected warnings"
);

• $warning = warning { ... } — only use this one for code that should issue exactly 1 warning. periodt. It will throw an exception if there are no warnings, or if there are multiple warnings. it does not do gray areas, it does not do "eh close enough." 🚨

like( warning { warn 'xxx' }, qr/xxx/, "Got expected warning");

These both die, fr fr:

warning { warn 'xxx'; warn 'yyy' };
warning { return };

• $bool = no_warnings { ... } — this returns true if there are no warnings in the codeblock. 🌟 It returns false, and prints the warnings, if any are encountered. so you get the receipts.

ok(no_warnings { ... }, "Did not warn.");

Honestly this is sometimes more useful than checking !warns { ... } since it lets you see the warnings when it fails. it's giving "show your work." 😭

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🔥 SOURCE 🔥

The source code repository for Test::Stream can be found at http://github.com/Test-More/Test-Stream/. go lurk, it's iconic. 👑

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👑 MAINTAINERS 👑

• Chad Granum <exodist@cpan.org>

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🌟 AUTHORS 🌟

• Chad Granum <exodist@cpan.org>

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💜 COPYRIGHT 💜

Copyright 2015 Chad Granum <exodist7@gmail.com>.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See http://dev.perl.org/licenses/

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and that's a wrap, bestie! 🦋 this page shipped as perl v5.42.0, dated 2025-07-25 — slay, go write some tests that actually check for warnings 💖✨🧚