More(3)
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, $test_name);
# Rather than print STDERR "# here's what went wrong\n"
diag("here's what went wrong");
like ($this, qr/that/, $test_name);
unlike($this, qr/that/, $test_name);
cmp_ok($this, '==', $that, $test_name);
is_deeply($complex_structure1, $complex_structure2, $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
STOP! 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.
The purpose of this module is to provide a wide range of testing utili-
ties. Various ways to say "ok" with better diagnostics, facilities to
skip tests, test future features and compare complicated data struc-
tures. While you can do almost anything with a simple "ok()" function,
it doesn't provide good diagnostic output.
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 preferred 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.
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( $^O eq 'MacOS' ) {
plan skip_all => 'Test irrelevant on MacOS';
}
else {
plan tests => 42;
}
Test names
By convention, each test is assigned a number in order. This is
largely done automatically for you. However, it's often very useful to
assign a name to each test. Which would you rather see:
ok 4
not ok 5
ok 6
or
ok 4 - basic multi-variable
not ok 5 - simple exponential
ok 6 - force == mass * acceleration
The later gives you some idea of what failed. It also makes it easier
to find the test in your script, simply search for "simple exponen-
tial".
All test functions take a name argument. It's optional, but highly
suggested that you use it.
I'm ok, you're not ok.
The basic purpose of this module is to print out either "ok #" or "not
ok #" depending on if a given test succeeded or failed. Everything
else is just gravy.
All of the following print "ok" or "not ok" depending on if the test
succeeded or failed. They all also return true or false, respectively.
ok
ok($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()" func-
tion 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 (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( $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.
unlike
unlike( $this, qr/that/, $test_name );
Works exactly as like(), only it checks if $this does not match the
given pattern.
cmp_ok
cmp_ok( $this, $op, $that, $test_name );
Halfway between ok() and is() lies cmp_ok(). This allows you to
compare two arguments using any binary perl operator.
# ok( $this eq $that );
cmp_ok( $this, 'eq', $that, 'this eq that' );
# ok( $this == $that );
cmp_ok( $this, '==', $that, 'this == that' );
# ok( $this && $that );
cmp_ok( $this, '&&', $that, 'this || that' );
...etc...
Its advantage over ok() is when the test fails you'll know what
$this and $that were:
not ok 1
# Failed test (foo.t at line 12)
# '23'
# &&
# undef
It's also useful in those cases where you are comparing numbers and
is()'s use of "eq" will interfere:
cmp_ok( $big_hairy_number, '==', $another_big_hairy_number );
can_ok
can_ok($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.
No matter how many @methods you check, a single can_ok() call
counts as one test. If you desire otherwise, use:
foreach my $meth (@methods) {
can_ok('Foo', $meth);
}
isa_ok
isa_ok($object, $class, $object_name);
isa_ok($ref, $type, $ref_name);
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.
It works on references, too:
isa_ok( $array_ref, 'ARRAY' );
The diagnostics of this test normally just refer to 'the object'.
If you'd like them to be more specific, you can supply an
$object_name (for example 'Test customer').
pass
fail
pass($test_name);
fail($test_name);
Sometimes you just want to say that the tests have passed. Usually
the case is you've got some complicated condition that is difficult
to wedge into an ok(). In this case, you can simply use pass() (to
declare the test ok) or fail (for not ok). They are synonyms for
ok(1) and ok(0).
Use these very, very, very sparingly.
Diagnostics
If you pick the right test function, you'll usually get a good idea of
what went wrong when it failed. But sometimes it doesn't work out that
way. So here we have ways for you to write your own diagnostic mes-
sages which are safer than just "print STDERR".
diag
diag(@diagnostic_message);
Prints a diagnostic message which is guaranteed not to interfere
with test output. Handy for this sort of thing:
ok( grep(/foo/, @users), "There's a foo user" ) or
diag("Since there's no foo, check that /etc/bar is set up right");
which would produce:
not ok 42 - There's a foo user
# Failed test (foo.t at line 52)
# Since there's no foo, check that /etc/bar is set up right.
You might remember "ok() or diag()" with the mnemonic "open() or
die()".
NOTE The exact formatting of the diagnostic output is still chang-
ing, but it is guaranteed that whatever you throw at it it won't
interfere with the test.
Module tests
You usually want to test if the module you're testing loads ok, rather
than just vomiting if its load fails. For such purposes we have
"use_ok" and "require_ok".
use_ok
BEGIN { use_ok($module); }
BEGIN { use_ok($module, @imports); }
These simply use the given $module and test to make sure the load
happened ok. It's recommended that you run use_ok() inside a BEGIN
block so its functions are exported at compile-time and prototypes
are properly honored.
If @imports are given, they are passed through to the use. So
this:
BEGIN { use_ok('Some::Module', qw(foo bar)) }
is like doing this:
use Some::Module qw(foo bar);
don't try to do this:
BEGIN {
use_ok('Some::Module');
...some code that depends on the use...
...happening at compile time...
}
instead, you want:
BEGIN { use_ok('Some::Module') }
BEGIN { ...some code that depends on the use... }
require_ok
require_ok($module);
Like use_ok(), except it requires the $module.
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).
For more details on the mechanics of skip and todo tests see Test::Har-
ness.
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 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;
ok( $lint, "Created object" );
$lint->parse( $html );
is( scalar $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.
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.
It's perfectly safe to nest SKIP blocks. Each SKIP block must have
the label "SKIP", or Test::More can't work its magic.
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.
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 fea-
ture:
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.
The nice part about todo tests, as opposed to simply commenting out
a block of tests, is it's 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.
Once a todo test starts succeeding, simply move it outside the
block. When the block is empty, delete it.
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 pos-
sible. 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.
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.
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.
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).
Comparison 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.
is_deeply
is_deeply( $this, $that, $test_name );
Similar to is(), except that if $this and $that are hash or array
references, it does a deep comparison walking each data structure
to see if they are equivalent. If the two structures are differ-
ent, it will display the place where they start differing.
Barrie Slaymaker's Test::Differences module provides more in-depth
functionality along these lines, and it plays well with Test::More.
NOTE Display of scalar refs is not quite 100%
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.
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.
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.
NOTES
Test::More is explicitly tested all the way back to perl 5.004.
Test::More is thread-safe for perl 5.8.0 and up.
BUGS and CAVEATS
Making your own ok()
If you are trying to extend Test::More, don't. Use Test::Builder
instead.
The eq_* family has 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 or todo your
end-users will have to upgrade Test::Harness to the latest one on
CPAN. If you avoid no_plan and TODO tests, the stock Test::Harness
will work fine.
If you simply depend on Test::More, it's own dependencies will
cause a Test::Harness upgrade.
HISTORY
This is a case of convergent evolution with Joshua Pritikin's Test mod-
ule. 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 provid-
ing 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.
SEE ALSO
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::Differences for more ways to test complex data structures. And
it plays well with Test::More.
Test is the old testing module. Its main benefit is that it has been
distributed with Perl since 5.004_05.
Test::Harness for details on how your test results are interpreted by
Perl.
Test::Unit describes a very featureful unit testing interface.
Test::Inline shows the idea of embedded testing.
SelfTest is another approach to embedded testing.
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, chromatic and the perl-qa gang.
COPYRIGHT
Copyright 2001 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 http://www.perl.com/perl/misc/Artistic.html
perl v5.8.0 2002-06-01 Test::More(3)
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