NAME

Test::More - yet another framework for writing test scripts

SYNOPSIS

use Test::More tests => $Num_Tests;
# or
use Test::More qw(no_plan);
# or
use Test::More skip_all => $reason;

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

# Various ways to say "ok"
ok($this eq $that, $test_name);

is  ($this, $that,    $test_name);
isnt($this, $that,    $test_name);
like($this, qr/that/, $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);

# Utility comparison functions.
eq_array(\@this, \@that);
eq_hash(\%this, \%that);
eq_set(\@this, \@that);

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

# UNIMPLEMENTED!!!
BAIL_OUT($why);

DESCRIPTION

If you're just getting started writing tests, have a look at Test::Simple first. This is a drop in replacement for Test::Simple which you can switch to once you get the hang of basic testing.

This module provides a very wide range of testing utilities. Various ways to say "ok", facilities to skip tests, test future features and compare complicated data structures.

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.

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

use Test::More tests => $Num_Tests;

There are rare cases when you will not know beforehand how many tests your script is going to run. In this case, you can declare that you have no plan. (Try to avoid using this as it weakens your test.)

use Test::More qw(no_plan);

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.

Test names

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

ok 4
not ok 5
ok 6

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. Its optional, but highly suggested that you use it.

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.

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($this eq $that, $test_name);

This simply evaluates any expression ($this eq $that 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.

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,       'items populated' );

(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 18 (foo.t at line 42)

This is actually Test::Simple's ok() routine.

is

isnt

is  ( $this, $that, $test_name );
isnt( $this, $that, $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" );

(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 1 (foo.t at line 139)
#          got: 'waffle'
#     expected: 'yarblokos'

So you can figure out what went wrong without rerunning the test.

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!  $pope->isa('Catholic') eq 1
is( $pope->isa('Catholic'), 1,        'Is the Pope Catholic?' );

This does not check if $pope-isa('Catholic')> is true, it checks if it returns 1. Very different. Similar caveats exist for false and 0. In these cases, use ok().

ok( $pope->isa('Catholic') ),         'Is the Pope Catholic?' );

For those grammatical pedants out there, there's an isn't() function which is an alias of isnt().

like

like( $this, qr/that/, $test_name );

Similar to ok(), like() matches $this against the regex qr/that/.

So this:

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

is similar to:

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

(Mnemonic "This is like that".)

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

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

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

Its advantages over ok() are similar to that of is() and isnt(). Better diagnostics on failure.

can_ok

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

Checks to make sure the $module or $object can do these @methods (works with functions, too).

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 better interface. Handy for quickly testing an interface.

isa_ok

isa_ok($object, $class);

Checks to see if the given $object->isa($class). Also checks to make sure the object was defined in the first place. Handy for this sort of thing:

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

where you'd otherwise have to write

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

to safeguard against your test script blowing up.

pass

fail

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

Sometimes you just want to say that the tests have passed. Usually the case is you've got some complicated condition that is difficult to wedge into an ok(). In this case, you can simply use pass() (to declare the test ok) or fail (for not ok). They are synonyms for ok(1) and ok(0).

Use these very, very, very sparingly.

Module tests

You usually want to test if the module you're testing loads ok, rather than just vomiting if its load fails. For such purposes we have use_ok and require_ok.

use_ok

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

These simply use the given $module and test to make sure the load happened ok. Its recommended that you run use_ok() inside a BEGIN block so its functions are exported at compile-time and prototypes are properly honored.

If @imports are given, they are 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);

require_ok

require_ok($module);

Like use_ok(), except it requires the $module.

Conditional tests

WARNING! The following describes an experimental interface that is subject to change WITHOUT NOTICE! Use at your peril.

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).

For more details on 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...

SKIP: BLOCK

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

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

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

SKIP: {
    skip "Pigs don't fly here", 2 unless Pigs->can('fly');

    my $pig = Pigs->new;
    $pig->takeoff;

    ok( $pig->altitude > 0,         'Pig is airborne' );
    ok( $pig->airspeed > 0,         '  and moving'    );
}

If pigs cannot fly, the whole block of tests will be skipped completely. Test::More will output special ok's which Test::Harness interprets as skipped tests. Its important to include $how_many tests are in the block so the total number of tests comes out right (unless you're using no_plan).

You'll typically use this when a feature is missing, like an optional module is not installed or the operating system doesn't have some feature (like fork() or symlinks) or maybe you need an Internet connection and one isn't available.

TODO: BLOCK

TODO: {
    local $TODO = $why;

    ...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.

The nice part about todo tests, as opposed to simply commenting out a block of tests, is it's like having a programatic 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.

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

Comparision functions

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

NOTE These are NOT well-tested on circular references. Nor am I quite sure what will happen with filehandles.

eq_array

eq_array(\@this, \@that);

Checks if two arrays are equivalent. This is a deep check, so multi-level structures are handled correctly.

eq_hash

eq_hash(\%this, \%that);

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

eq_set

eq_set(\@this, \@that);

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.

NOTES

Test::More is explicitly tested all the way back to perl 5.004.

BUGS and CAVEATS

Making your own ok()

This will not do what you mean:

sub my_ok {
    ok( @_ );
}

my_ok( 2 + 2 == 5, 'Basic addition' );

since ok() takes it's arguments as scalars, it will see the length of @_ (2) and always pass the test. You want to do this instead:

sub my_ok {
    ok( $_[0], $_[1] );
}

The other functions act similiarly.

The eq_* family have some caveats.

Test::Harness upgrades

no_plan and todo depend on new Test::Harness features and fixes. If you're going to distribute tests that use no_plan your end-users will have to upgrade Test::Harness to the latest one on CPAN.

If you simply depend on Test::More, it's own dependencies will cause a Test::Harness upgrade.

AUTHOR

Michael G Schwern <schwern@pobox.com> with much inspiration from Joshua Pritikin's Test module and lots of discussion with Barrie Slaymaker and the perl-qa gang.

HISTORY

This is a case of convergent evolution with Joshua Pritikin's Test module. I was largely unware 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.

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