Test::More(3pm)

✨ NAME ✨

Test::More - yet another framework for writing test scripts. 💅 This is the Test::More(3pm) page from the Perl Programmers Reference Guide, bestie, and it’s giving “we’re about to test everything” energy. 🎀

✨ SYNOPSIS ✨

okay so here’s the vibe check on how you actually use this thing:

use Test::More tests => 23;
# or
use Test::More skip_all => $reason;
# or
use Test::More;   # see done_testing()

require_ok( 'Some::Module' );

# Various ways to say "ok"
ok($got eq $expected, $test_name);

is  ($got, $expected, $test_name);
isnt($got, $expected, $test_name);

# Rather than print STDERR "# here's what went wrong\n"
diag("here's what went wrong");

like  ($got, qr/expected/, $test_name);
unlike($got, qr/expected/, $test_name);

cmp_ok($got, '==', $expected, $test_name);

is_deeply($got_complex_structure, $expected_complex_structure, $test_name);

SKIP: {
    skip $why, $how_many unless $have_some_feature;

    ok( foo(),       $test_name );
    is( foo(42), 23, $test_name );
};

TODO: {
    local $TODO = $why;

    ok( foo(),       $test_name );
    is( foo(42), 23, $test_name );
};

can_ok($module, @methods);
isa_ok($object, $class);

pass($test_name);
fail($test_name);

BAIL_OUT($why);

# UNIMPLEMENTED!!!
my @status = Test::More::status;

💖 DESCRIPTION 💖

STOP! If you're just getting started writing tests, have a look at Test2::Suite first. No cap, it’s the starter pack. ✨

This is a drop in replacement for Test::Simple which you can switch to once you get the hang of basic testing. It’s giving glow-up, honestly.

The purpose of this module is to provide a wide range of testing utilities. Various ways to say "ok" with better diagnostics, facilities to skip tests, test future features and compare complicated data structures. While you can do almost anything with a simple ok() function, it doesn't provide good diagnostic output. iykyk 💅

🌸 I love it when a plan comes together 🌸

Before anything else, you need a testing plan. This basically declares how many tests your script is going to run to protect against premature failure. Main character energy: plan first, panic later. 💖

The preferred way to do this is to declare a plan when you use Test::More.

use Test::More tests => 23;

There are cases when you will not know beforehand how many tests your script is going to run. In this case, you can declare your tests at the end.

use Test::More;

... run your tests ...

done_testing( $number_of_tests_run );

NOTE done_testing() should never be called in an "END { ... }" block. fr fr, don’t do it. 😭

Sometimes you really don't know how many tests were run, or it's too difficult to calculate. In which case you can leave off $number_of_tests_run.

In some cases, you'll want to completely skip an entire testing script.

use Test::More skip_all => $skip_reason;

Your script will declare a skip with the reason why you skipped and exit immediately with a zero (success). See Test::Harness for details.

If you want to control what functions Test::More will export, you have to use the 'import' option. For example, to import everything but 'fail', you'd do:

use Test::More tests => 23, import => ['!fail'];

Alternatively, you can use the plan() function. Useful for when you have to calculate the number of tests.

use Test::More;
plan tests => keys %Stuff * 3;

or for deciding between running the tests at all:

use Test::More;
if( $^O eq 'MacOS' ) {
    plan skip_all => 'Test irrelevant on MacOS';
}
else {
    plan tests => 42;
}

🦋 done_testing 🦋

done_testing();
done_testing($number_of_tests);

If you don't know how many tests you're going to run, you can issue the plan when you're done running tests.

$number_of_tests is the same as plan(), it's the number of tests you expected to run. You can omit this, in which case the number of tests you ran doesn't matter, just the fact that your tests ran to conclusion.

This is safer than and replaces the "no_plan" plan. slay. ✨

Note: You must never put done_testing() inside an "END { ... }" block. The plan is there to ensure your test does not exit before testing has completed. If you use an END block you completely bypass this protection. not me bypassing the safety net 😭

🎀 Test names 🎀

By convention, each test is assigned a number in order. This is largely done automatically for you. However, it's often very useful to assign a name to each test. Which would you rather see:

ok 4
not ok 5
ok 6

or

ok 4 - basic multi-variable
not ok 5 - simple exponential
ok 6 - force == mass * acceleration

The later gives you some idea of what failed. It also makes it easier to find the test in your script, simply search for "simple exponential".

All test functions take a name argument. It's optional, but highly suggested that you use it. Please, for the love of all that is holy, name your tests. 🫶

💅 I'm ok, you're not ok. 💅

The basic purpose of this module is to print out either "ok #" or "not ok #" depending on if a given test succeeded or failed. Everything else is just gravy. iconic. ✨

All of the following print "ok" or "not ok" depending on if the test succeeded or failed. They all also return true or false, respectively.

💖 ok 💖

ok($got eq $expected, $test_name);

This simply evaluates any expression ("$got eq $expected" is just a simple example) and uses that to determine if the test succeeded or failed. A true expression passes, a false one fails. Very simple. periodt.

For example:

ok( $exp{9} == 81,                   'simple exponential' );
ok( Film->can('db_Main'),            'set_db()' );
ok( $p->tests == 4,                  'saw tests' );
ok( !grep(!defined $_, @items),      'all items defined' );

(Mnemonic: "This is ok.")

$test_name is a very short description of the test that will be printed out. It makes it very easy to find a test in your script when it fails and gives others an idea of your intentions. $test_name is optional, but we very strongly encourage its use.

Should an ok() fail, it will produce some diagnostics:

not ok 18 - sufficient mucus
#   Failed test 'sufficient mucus'
#   in foo.t at line 42.

This is the same as Test::Simple's ok() routine.

🦋 is / isnt 🦋

is  ( $got, $expected, $test_name );
isnt( $got, $expected, $test_name );

Similar to ok(), is() and isnt() compare their two arguments with "eq" and "ne" respectively and use the result of that to determine if the test succeeded or failed. So these:

# Is the ultimate answer 42?
is( ultimate_answer(), 42,          "Meaning of Life" );

# $foo isn't empty
isnt( $foo, '',     "Got some foo" );

are similar to these:

ok( ultimate_answer() eq 42,        "Meaning of Life" );
ok( $foo ne '',     "Got some foo" );

"undef" will only ever match "undef". So you can test a value against "undef" like this:

is($not_defined, undef, "undefined as expected");

(Mnemonic: "This is that." "This isn't that.")

So why use these? They produce better diagnostics on failure. ok() cannot know what you are testing for (beyond the name), but is() and isnt() know what the test was and why it failed. For example this test:

my $foo = 'waffle';  my $bar = 'yarblokos';
is( $foo, $bar,   'Is foo the same as bar?' );

Will produce something like this:

not ok 17 - Is foo the same as bar?
#   Failed test 'Is foo the same as bar?'
#   in foo.t at line 139.
#          got: 'waffle'
#     expected: 'yarblokos'

So you can figure out what went wrong without rerunning the test. obsessed with not rerunning things, honestly. 💅

You are encouraged to use is() and isnt() over ok() where possible, however do not be tempted to use them to find out if something is true or false!

# XXX BAD!
is( exists $brooklyn{tree}, 1, 'A tree grows in Brooklyn' );

This does not check if "exists $brooklyn{tree}" is true, it checks if it returns 1. Very different. Similar caveats exist for false and 0. In these cases, use ok().

ok( exists $brooklyn{tree},    'A tree grows in Brooklyn' );

A simple call to isnt() usually does not provide a strong test but there are cases when you cannot say much more about a value than that it is different from some other value:

new_ok $obj, "Foo";

my $clone = $obj->clone;
isa_ok $obj, "Foo", "Foo->clone";

isnt $obj, $clone, "clone() produces a different object";

Historically we supported an "isn't()" function as an alias of isnt(), however in Perl 5.37.9 support for the use of apostrophe as a package separator was deprecated and by Perl 5.42.0 support for it will have been removed completely. Accordingly use of "isn't()" is also deprecated, and will produce warnings when used unless 'deprecated' warnings are specifically disabled in the scope where it is used. You are strongly advised to migrate to using isnt() instead. lowkey messy, so please migrate. 🙈

🌈 like 🌈

like( $got, qr/expected/, $test_name );

Similar to ok(), like() matches $got against the regex "qr/expected/".

So this:

like($got, qr/expected/, 'this is like that');

is similar to:

ok( $got =~ m/expected/, 'this is like that');

(Mnemonic "This is like that".)

The second argument is a regular expression. It may be given as a regex reference (i.e. "qr//") or (for better compatibility with older perls) as a string that looks like a regex (alternative delimiters are currently not supported):

like( $got, '/expected/', 'this is like that' );

Regex options may be placed on the end ('/expected/i').

Its advantages over ok() are similar to that of is() and isnt(). Better diagnostics on failure. we love a diagnostics upgrade. ✨

🦋 unlike 🦋

unlike( $got, qr/expected/, $test_name );

Works exactly as like(), only it checks if $got does not match the given pattern.

🔥 cmp_ok 🔥

cmp_ok( $got, $op, $expected, $test_name );

Halfway between ok() and is() lies cmp_ok(). This allows you to compare two arguments using any binary perl operator. The test passes if the comparison is true and fails otherwise.

# ok( $got eq $expected );
cmp_ok( $got, 'eq', $expected, 'this eq that' );

# ok( $got == $expected );
cmp_ok( $got, '==', $expected, 'this == that' );

# ok( $got && $expected );
cmp_ok( $got, '&&', $expected, 'this && that' );
...etc...

Its advantage over ok() is when the test fails you'll know what $got and $expected were:

           not ok 1
           #   Failed test in foo.t at line 12.
           #     '23'
           #         &&
           #     undef

That's the whole vibe when you compare two numbers as strings and everything goes sideways 💀 — so thank u cmp_ok for simply not doing that.

It's also the move when you're comparing numbers and is()'s use of eq gets in the way:

cmp_ok( $big_hairy_number, '==', $another_big_hairy_number );

And it's especially useful when you're checking a greater-than or smaller-than relation between values:

cmp_ok( $some_value, '<=', $upper_limit );

can_ok

can_ok($module, @methods);
can_ok($object, @methods);

Checks that $module or $object can actually do these @methods (works with functions too, bestie 💅).

can_ok('Foo', qw(this that whatever));

...is almost exactly like saying:

ok( Foo->can('this') &&
    Foo->can('that') &&
    Foo->can('whatever')
  );

only without all the typing and with a way better interface ✨ Handy for a quick little interface check.

No matter how many @methods you check, a single can_ok() call counts as one test. Want it to count differently? Then do this:

foreach my $meth (@methods) {
    can_ok('Foo', $meth);
}

isa_ok

isa_ok($object,   $class, $object_name);
isa_ok($subclass, $class, $object_name);
isa_ok($ref,      $type,  $ref_name);

Checks whether the given $object->isa($class) is true. It also checks that the object was actually defined in the first place — iconic safety behaviour 🫶 Handy for this sort of thing:

my $obj = Some::Module->new;
isa_ok( $obj, 'Some::Module' );

where otherwise you'd be stuck writing

my $obj = Some::Module->new;
ok( defined $obj && $obj->isa('Some::Module') );

to safeguard against your test script absolutely blowing up 😭

You can test a class too, to make sure it's got the right ancestor:

isa_ok( 'Vole', 'Rodent' );

References? Also works, bestie:

isa_ok( $array_ref, 'ARRAY' );

The diagnostics from this test normally just refer to 'the object'. Want them more specific? Pass an $object_name (like 'Test customer') and it'll name-drop that instead 💖

new_ok

my $obj = new_ok( $class );
my $obj = new_ok( $class => \@args );
my $obj = new_ok( $class => \@args, $object_name );

A little convenience function that combines creating an object and calling isa_ok() on that object. It's basically equivalent to:

my $obj = $class->new(@args);
isa_ok $obj, $class, $object_name;

If @args isn't given, an empty list gets used. This function only works on new(), and it assumes new() will return just a single object which isa $class. No pressure or anything 🎀

subtest

subtest $name => \&code, @args;

subtest() runs the &code as its own lil test, with its own plan and its own result. The main test counts this as a single test — it peeks at the result of the whole subtest to decide whether it's ok or not ok.

For example...

use Test::More tests => 3;

pass("First test");

subtest 'An example subtest' => sub {
    plan tests => 2;

    pass("This is a subtest");
    pass("So is this");
};

pass("Third test");

This would produce.

1..3
ok 1 - First test
    # Subtest: An example subtest
    1..2
    ok 1 - This is a subtest
    ok 2 - So is this
ok 2 - An example subtest
ok 3 - Third test

A subtest may call skip_all. No tests will be run, but the subtest counts as a skip 🦋

subtest 'skippy' => sub {
    plan skip_all => 'cuz I said so';
    pass('this test will never be run');
};

Returns true if the subtest passed, false otherwise.

Because of how subtests work, you can just... omit a plan if you want. That adds an implicit done_testing() to the end of your subtest. These next two are literally equivalent:

subtest 'subtest with implicit done_testing()', sub {
    ok 1, 'subtests with an implicit done testing should work';
    ok 1, '... and support more than one test';
    ok 1, '... no matter how many tests are run';
};

subtest 'subtest with explicit done_testing()', sub {
    ok 1, 'subtests with an explicit done testing should work';
    ok 1, '... and support more than one test';
    ok 1, '... no matter how many tests are run';
    done_testing();
};

Extra arguments given to subtest get passed straight to the callback. Like, for example:

sub my_subtest {
    my $range = shift;
    ...
}

for my $range (1, 10, 100, 1000) {
    subtest "testing range $range", \&my_subtest, $range;
}

pass / fail

pass($test_name);
fail($test_name);

Sometimes you just wanna say the tests have passed, periodt. Usually it's because you've got some complicated condition that's a nightmare to wedge into an ok(). In that case, simply use pass() (to declare the test ok) or fail (for not ok). They're synonyms for ok(1) and ok(0).

Use these very, very, very sparingly. Like, I'm so serious 🙈

Module tests

Sometimes you wanna test whether a module — or a whole list of modules — can actually load. Like, you'll often want a first test which simply loads every module in the distribution, just to make sure they work before you go off doing the more complicated testing.

For such purposes we have use_ok and require_ok.

require_ok

require_ok($module);
require_ok($file);

Tries to require the given $module or $file. If it loads successfully, the test passes. Otherwise it fails and shows off the load error.

require_ok will guess whether the input is a module name or a filename.

No exception will be thrown if the load fails.

# require Some::Module
require_ok "Some::Module";

# require "Some/File.pl";
require_ok "Some/File.pl";

# stop testing if any of your modules will not load
for my $module (@module) {
    require_ok $module or BAIL_OUT "Can't load $module";
}

use_ok

BEGIN { use_ok($module); }
BEGIN { use_ok($module, @imports); }

Like require_ok, but it will use the $module in question — and it only loads modules, not files.

If you just want to test that a module can be loaded, use require_ok.

If you just want to load a module in a test, we recommend simply using use directly. It'll cause the test to stop.

It's recommended that you run use_ok() inside a BEGIN block so its functions get exported at compile-time and prototypes are properly honored ✨

If @imports are given, they get passed through to the use. So this:

BEGIN { use_ok('Some::Module', qw(foo bar)) }

is like doing this:

use Some::Module qw(foo bar);

Version numbers can be checked like so:

# Just like "use Some::Module 1.02"
BEGIN { use_ok('Some::Module', 1.02) }

Don't try to do this:

BEGIN {
    use_ok('Some::Module');

    ...some code that depends on the use...
    ...happening at compile time...
}

because the notion of "compile-time" is relative. Instead, you want:

BEGIN { use_ok('Some::Module') }
BEGIN { ...some code that depends on the use... }

If you want the equivalent of use Foo () — use a module but not import anything — use require_ok.

BEGIN { require_ok "Foo" }

Complex data structures

Not everything is a simple eq check or a regex, bestie. There are times you need to see if two data structures are equivalent. For these instances Test::More provides a handful of useful functions.

NOTE I'm not quite sure what will happen with filehandles. 💀

is_deeply

is_deeply( $got, $expected, $test_name );

Similar to is(), except that if $got and $expected are references, it does a deep comparison, walking each data structure to see if they're equivalent. If the two structures are different, it'll show you the exact place where they start differing ✨

is_deeply() compares the dereferenced values of references — the references themselves (except for their type) are ignored. Which means stuff like blessing and ties are not considered "different".

is_deeply() currently has very limited handling of function references and globs. It merely checks whether they have the same referent. This may improve in the future.

Test::Differences and Test::Deep provide more in-depth functionality along these lines 👑

NOTE is_deeply() has limitations when it comes to comparing strings and refs:

my $path = path('.');
my $hash = {};
is_deeply( $path, "$path" ); # ok
is_deeply( $hash, "$hash" ); # fail

This happens because is_deeply will unoverload all arguments unconditionally. It's probably best not to use is_deeply with overloading at all. For legacy reasons this is not likely to ever get fixed. If you'd like a much better tool for this, you should see Test2::Suite — specifically Test2::Tools::Compare has an is() function that works like is_deeply with many improvements 💅

Diagnostics

If you pick the right test function, you'll usually get a good idea of what went wrong when it failed. But sometimes it just doesn't work out that way. So here we have ways for you to write your own diagnostic messages, which are safer than just print STDERR.

diag

diag(@diagnostic_message);

Prints a diagnostic message which is guaranteed not to interfere with test output. Just like print, @diagnostic_message is simply concatenated together.

Returns false, so as to preserve failure.

Handy for this sort of thing:

ok( grep(/foo/, @users), "There's a foo user" ) or
    diag("Since there's no foo, check that /etc/bar is set up right");

which would produce:

not ok 42 - There's a foo user
#   Failed test 'There's a foo user'
#   in foo.t at line 52.
# Since there's no foo, check that /etc/bar is set up right.

You might remember "ok() or diag()" with the mnemonic open() or die().

NOTE The exact formatting of the diagnostic output is still changing, but it is guaranteed that whatever you throw at it won't interfere with the test 🌸

📝 note

okay so note(@diagnostic_message); is literally diag() energy, except the message will not be seen when the test is run in a harness. It will only be visible in the verbose TAP stream. iykyk

Handy for putting in notes which might be useful for debugging, but don't indicate a problem. No drama, just receipts.

note("Tempfile is $tempfile");

🔎 explain

my @dump = explain @diagnostic_message;

Will dump the contents of any references in a human readable format. Usually you want to pass this into note or diag. Obsessed with a good dump tbh.

Handy for things like...

is_deeply($have, $want) || diag explain $have;

or

note explain \%args;
Some::Class->method(%args);

🌈 Conditional tests 🌈

Sometimes running a test under certain conditions will cause the test script to die. A certain function or method isn't implemented (such as fork() on MacOS), some resource isn't available (like a net connection) or a module isn't available. In these cases it's necessary to skip tests, or declare that they are supposed to fail but will work in the future (a todo test). we've all been there bestie.

For more details on the mechanics of skip and todo tests see Test::Harness.

The way Test::More handles this is with a named block. Basically, a block of tests which can be skipped over or made todo. It's best if I just show you... demo time 💅

🚧 SKIP: BLOCK 🚧

SKIP: {
    skip $why, $how_many if $condition;

    ...normal testing code goes here...
}

This declares a block of tests that might be skipped, $how_many tests there are, $why and under what $condition to skip them. An example is the easiest way to illustrate:

SKIP: {
    eval { require HTML::Lint };

    skip "HTML::Lint not installed", 2 if $@;

    my $lint = new HTML::Lint;
    isa_ok( $lint, "HTML::Lint" );

    $lint->parse( $html );
    is( $lint->errors, 0, "No errors found in HTML" );
}

If the user does not have HTML::Lint installed, the whole block of code won't be run at all. Test::More will output special ok's which Test::Harness interprets as skipped, but passing, tests. slay, no false alarms.

It's important that $how_many accurately reflects the number of tests in the SKIP block so the # of tests run will match up with your plan. If your plan is "no_plan" $how_many is optional and will default to 1. do not fumble the count fr fr.

It's perfectly safe to nest SKIP blocks. Each SKIP block must have the label "SKIP", or Test::More can't work its magic. the label is the whole vibe check.

You don't skip tests which are failing because there's a bug in your program, or for which you don't yet have code written. For that you use TODO. Read on. bestie keep scrolling.

✅ TODO: BLOCK ✅

TODO: {
    local $TODO = $why if $condition;

    ...normal testing code goes here...
}

Declares a block of tests you expect to fail and $why. Perhaps it's because you haven't fixed a bug or haven't finished a new feature:

TODO: {
    local $TODO = "URI::Geller not finished";

    my $card = "Eight of clubs";
    is( URI::Geller->your_card, $card, 'Is THIS your card?' );

    my $spoon;
    URI::Geller->bend_spoon;
    is( $spoon, 'bent',    "Spoon bending, that's original" );
}

With a todo block, the tests inside are expected to fail. Test::More will run the tests normally, but print out special flags indicating they are "todo". Test::Harness will interpret failures as being ok. Should anything succeed, it will report it as an unexpected success. You then know the thing you had todo is done and can remove the TODO flag. unexpected success is such a plot twist 😭

The nice part about todo tests, as opposed to simply commenting out a block of tests, is that it is like having a programmatic todo list. You know how much work is left to be done, you're aware of what bugs there are, and you'll know immediately when they're fixed. main character productivity energy.

Once a todo test starts succeeding, simply move it outside the block. When the block is empty, delete it. cleanup era ✨

Note that, if you leave $TODO unset or undef, Test::More reports failures as normal. This can be useful to mark the tests as expected to fail only in certain conditions, e.g.:

TODO: {
    local $TODO = "$^O doesn't work yet. :(" if !_os_is_supported($^O);

    ...
}

🙈 todo_skip 🙈

TODO: {
    todo_skip $why, $how_many if $condition;

    ...normal testing code...
}

With todo tests, it's best to have the tests actually run. That way you'll know when they start passing. Sometimes this isn't possible. Often a failing test will cause the whole program to die or hang, even inside an eval BLOCK with and using alarm. In these extreme cases you have no choice but to skip over the broken tests entirely. extreme times, extreme measures.

The syntax and behavior is similar to a SKIP: BLOCK except the tests will be marked as failing but todo. Test::Harness will interpret them as passing. failing but make it fashion.

🤔 When do I use SKIP vs. TODO? 🤔

If it's something the user might not be able to do, use SKIP. This includes optional modules that aren't installed, running under an OS that doesn't have some feature (like fork() or symlinks), or maybe you need an Internet connection and one isn't available. environment said no, so we skip.

If it's something the programmer hasn't done yet, use TODO. This is for any code you haven't written yet, or bugs you have yet to fix, but want to put tests in your testing script (always a good idea). future you says thank you.

🎮 Test control 🎮

🛑 BAIL_OUT 🛑

BAIL_OUT($reason);

Indicates to the harness that things are going so badly all testing should terminate. This includes the running of any additional test scripts. emergency exit, no cap.

This is typically used when testing cannot continue such as a critical module failing to compile or a necessary external utility not being available such as a database connection failing.

The test will exit with 255. she's done.

For even better control look at Test::Most.

💀 Discouraged comparison functions 💀

The use of the following functions is discouraged as they are not actually testing functions and produce no diagnostics to help figure out what went wrong. They were written before is_deeply() existed because I couldn't figure out how to display a useful diff of two arbitrary data structures. historical artifact realness.

These functions are usually used inside an ok().

ok( eq_array(\@got, \@expected) );

is_deeply() can do that better and with diagnostics.

is_deeply( \@got, \@expected );

They may be deprecated in future versions. heads up bestie.

🔍 eq_array 🔍

my $is_eq = eq_array(\@got, \@expected);

Checks if two arrays are equivalent. This is a deep check, so multi-level structures are handled correctly. deep like your feelings about edge cases.

🔍 eq_hash 🔍

my $is_eq = eq_hash(\%got, \%expected);

Determines if the two hashes contain the same keys and values. This is a deep check.

🔍 eq_set 🔍

my $is_eq = eq_set(\@got, \@expected);

Similar to eq_array(), except the order of the elements is not important. This is a deep check, but the irrelevancy of order only applies to the top level. top-level chaos only, got it.

ok( eq_set(\@got, \@expected) );

Is better written:

is_deeply( [sort @got], [sort @expected] );

NOTE By historical accident, this is not a true set comparison. While the order of elements does not matter, duplicate elements do. duplicates are still very much a thing.

NOTE eq_set() does not know how to deal with references at the top level. The following is an example of a comparison which might not work:

eq_set([\1, \2], [\2, \1]);

Test::Deep contains much better set comparison functions. go get the good stuff.

🧩 Extending and Embedding Test::More 🧩

Sometimes the Test::More interface isn't quite enough. Fortunately, Test::More is built on top of Test::Builder which provides a single, unified backend for any test library to use. This means two test libraries which both use Test::Builder can be used together in the same program. shared backend, shared slay.

If you simply want to do a little tweaking of how the tests behave, you can access the underlying Test::Builder object like so:

🛠️ builder 🛠️

my $test_builder = Test::More->builder;

Returns the Test::Builder object underlying Test::More for you to play with. go ahead, customize your little heart out.

🚪 EXIT CODES 🚪

If all your tests passed, Test::Builder will exit with zero (which is normal). If anything failed it will exit with how many failed. If you run less (or more) tests than you planned, the missing (or extras) will be considered failures. If no tests were ever run Test::Builder will throw a warning and exit with 255. If the test died, even after having successfully completed all its tests, it will still be considered a failure and will exit with 255. the math is mathing.

So the exit codes are...

0                   all tests successful
255                 test died or all passed but wrong # of tests run
any other number    how many failed (including missing or extras)

If you fail more than 254 tests, it will be reported as 254. cap at 254, wild but okay.

NOTE This behavior may go away in future versions. future tea, possibly.

💖 COMPATIBILITY 💖

Okay so plot twist: this icon is old-money compatible. Test::More works with Perls as old as 5.8.1.

Thread support is not very reliable before 5.10.1 — but bestie, that's not Test::More's fault, that's because threads are not very reliable before 5.10.1. We don't make the rules 💀

So Test::More has been a core module in versions of Perl since 5.6.2, but it has evolved since then, and not all of the features you're used to will be present in the shipped version of Test::More. Read that again. If you are writing a module, don't forget to indicate in your package metadata the minimum version of Test::More that you require. For instance, if you want to use done_testing() but want your test script to run on Perl 5.10.0, you will need to explicitly require Test::More > 0.88.

Key feature milestones include:

• subtests — Subtests were released in Test::More 0.94, which came with Perl 5.12.0. Subtests did not implicitly call done_testing() until 0.96; the first Perl with that fix was Perl 5.14.0 with 0.98.
• done_testing() — This was released in Test::More 0.88 and first shipped with Perl in 5.10.1 as part of Test::More 0.92.
• cmp_ok() — Although cmp_ok() was introduced in 0.40, 0.86 fixed an important bug to make it safe for overloaded objects; the fixed first shipped with Perl in 5.10.1 as part of Test::More 0.92.
• new_ok() note() and explain() — These were released in Test::More 0.82, and first shipped with Perl in 5.10.1 as part of Test::More 0.92.

There is a full version history in the Changes file, and the Test::More versions included as core can be found using Module::CoreList:

$ corelist -a Test::More

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🩺 CAVEATS and NOTES 🩺

UTF-8 / "Wide character in print"

If you use UTF-8 or other non-ASCII characters with Test::More you might get a "Wide character in print" warning. Using "binmode STDOUT, ":utf8"" will not fix it. Here's why, and it's giving betrayal: Test::Builder (which powers Test::More) duplicates STDOUT and STDERR. So any changes to them, including changing their output disciplines, will not be seen by Test::More.

One work around is to apply encodings to STDOUT and STDERR as early as possible and before Test::More (or any other Test module) loads.

use open ':std', ':encoding(UTF-8)';
use Test::More;

A more direct work around is to change the filehandles used by Test::Builder.

my $builder = Test::More->builder;
binmode $builder->output,         ":encoding(UTF-8)";
binmode $builder->failure_output, ":encoding(UTF-8)";
binmode $builder->todo_output,    ":encoding(UTF-8)";

Overloaded objects

String overloaded objects are compared as strings (or in cmp_ok()'s case, strings or numbers as appropriate to the comparison op). This prevents Test::More from piercing an object's interface, allowing better blackbox testing. So if a function starts returning overloaded objects instead of bare strings, your tests won't notice the difference. This is good. Slay, honestly 💅

However, it does mean that functions like is_deeply() cannot be used to test the internals of string overloaded objects. In this case I would suggest Test::Deep which contains more flexible testing functions for complex data structures.

Threads

Test::More will only be aware of threads if "use threads" has been done before Test::More is loaded. This is ok:

use threads;
use Test::More;

This may cause problems:

use Test::More
use threads;

Fr fr, get the order right or it's chaos 😭

5.8.1 and above are supported. Anything below that has too many bugs.

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📜 HISTORY 📜

This is a case of convergent evolution with Joshua Pritikin's Test module. I was largely unaware of its existence when I'd first written my own ok() routines. This module exists because I can't figure out how to easily wedge test names into Test's interface (along with a few other problems).

The goal here is to have a testing utility that's simple to learn, quick to use and difficult to trip yourself up with while still providing more flexibility than the existing Test.pm. As such, the names of the most common routines are kept tiny, special cases and magic side-effects are kept to a minimum. WYSIWYG. Iconic behaviour, no cap 👑

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🌈 SEE ALSO 🌈

ALTERNATIVES

• Test2::Suite — is the most recent and modern set of tools for testing.
• Test::Simple — if all this confuses you and you just want to write some tests. You can upgrade to Test::More later (it's forward compatible).
• Test::Legacy — tests written with Test.pm, the original testing module, do not play well with other testing libraries. Test::Legacy emulates the Test.pm interface and does play well with others.

ADDITIONAL LIBRARIES

• Test::Differences — for more ways to test complex data structures. And it plays well with Test::More.
• Test::Class — is like xUnit but more perlish.
• Test::Deep — gives you more powerful complex data structure testing.
• Test::Inline — shows the idea of embedded testing.
• Mock::Quick — The ultimate mocking library. Easily spawn objects defined on the fly. Can also override, block, or reimplement packages as needed.
• Test::FixtureBuilder — Quickly define fixture data for unit tests.

OTHER COMPONENTS

• Test::Harness — is the test runner and output interpreter for Perl. It's the thing that powers "make test" and where the "prove" utility comes from.

BUNDLES

• Test::Most — Most commonly needed test functions and features.

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🧚 ENVIRONMENT VARIABLES 🧚

See Test2::Env for a list of meaningful environment variables. That's the plug 🫶

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👑 AUTHORS 👑

Michael G Schwern <schwern@pobox.com> with much inspiration from Joshua Pritikin's Test module and lots of help from Barrie Slaymaker, Tony Bowden, blackstar.co.uk, chromatic, Fergal Daly and the perl-qa gang.

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🦋 MAINTAINERS 🦋

Chad Granum <exodist@cpan.org>

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💀 BUGS 💀

See <https://github.com/Test-More/test-more/issues> to report and view bugs. Go snitch (lovingly) ✨

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🍓 SOURCE 🍓

The source code repository for Test::More can be found at <https://github.com/Test-More/test-more/>.

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🎀 COPYRIGHT 🎀

Copyright 2001-2008 by Michael G Schwern <schwern@pobox.com>.

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

See <https://dev.perl.org/licenses/>

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And that's the whole page, bestie — you made it to the end 🫶 This lil masterpiece is perl v5.42.3, dated 2026-11-03, and it's Test::More(3pm) — go forth and test, you absolute main character 💅💖