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Test::More(3) - Test::More - yet another framework for writing test scripts - man 3 Test::More

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Test::More(3)          Perl Programmers Reference Guide          Test::More(3)

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

         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);


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

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

         # UNIMPLEMENTED!!!

       STOP! If you're just getting started writing tests, have a look(1,8,3 Search::Dict) at
       Test::Simple first.  This is a drop in(1,8) replacement for Test::Simple
       which you can switch(1,n) 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

       The preferred way to do this is to declare a plan when you "use

         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(3,n,1 builtins) 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(3,n)( $^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(1,8) 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


         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(1,8) your script, simply search for "simple exponen-

       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(3,n) a given test succeeded or failed.  Everything
       else is just gravy.

       All of the following print "ok" or "not ok" depending on if(3,n) the test
       succeeded or failed.  They all also return true or false, respectively.

             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(3,n) 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(1,8) 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  ( $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(3,n) 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 (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(3,n) 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(3,n) "$pope-"isa('Catholic')> is true, it checks
           if(3,n) 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( $this, qr/that/, $test_name );

           Similar to ok(), like() matches $this against the regex(3,7) "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(3,7) reference (i.e. "qr//") or (for better compatibility with
           older perls) as a string(3,n) that looks like a regex(3,7) (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( $this, qr/that/, $test_name );

           Works exactly as like(), only it checks if(3,n) $this does not match the
           given pattern.

             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' );

           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(1,8) 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($module, @methods);
             can_ok($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') &&

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

           Checks to see if(3,n) the given $object->isa($class).  Also checks to
           make sure the object was defined in(1,8) the first place.  Handy for
           this sort(1,3) of thing:

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

           where you'd otherwise have to write(1,2)

               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').


           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.


       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(1,2) your own diagnostic mes-
       sages which are safer than just "print STDERR".


           Prints a diagnostic message which is guaranteed not to interfere
           with test output.  Handy for this sort(1,3) of thing:

               ok( grep(/foo/, @users(1,5)), "There's a foo user" ) or
                   diag("Since there's no foo, check that /etc/bar is set(7,n,1 builtins) 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(7,n,1 builtins) up right.

           You might remember "ok() or diag()" with the mnemonic "open(2,3,n)() or

           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(3,n) the module you're testing loads ok, rather
       than just vomiting if(3,n) its load(7,n) fails.  For such purposes we have
       "use_ok" and "require_ok".

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

           These simply use the given $module and test to make sure the load(7,n)
           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

              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 {

                  ...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... }


           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(1,8) the
       future (a todo test).

       For more details on the mechanics of skip and todo tests see Test::Har-

       The way Test::More handles this is with a named(5,8) block.  Basically, a
       block of tests which can be skipped over or made todo.  It's best if(3,n) I
       just show you...

       SKIP: BLOCK
             SKIP: {
                 skip $why, $how_many if(3,n) $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(3,n) $@;

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

                   $lint->parse( $html );
                   is( $lint->errors, 0, "No errors found in(1,8) 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(1,8) 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(1,8)
           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(3,n) $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-

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

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

                   my $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(1,2) 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(3x,7,3x curs_move) it outside the
           block.  When the block is empty, delete it.

               TODO: {
                   todo_skip $why, $how_many if(3,n) $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(1,2)".  In these
           extreme cases you have no choice but to skip over the broken tests

           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(1,8) your testing script (always a good

       Comparison functions

       Not everything is a simple eq check or regex.  There are times you need
       to see if(3,n) 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( $this, $that, $test_name );

           Similar to is(), except that if(3,n) $this and $that are hash or array
           references, it does a deep comparison walking each data structure
           to see if(3,n) 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(\@this, \@that);

           Checks if(3,n) two arrays are equivalent.  This is a deep check, so
           multi-level structures are handled correctly.

             eq_hash(\%this, \%that);

           Determines if(3,n) the two hashes contain the same keys and values.
           This is a deep check.

             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.

           NOTE By historical accident, this is not a true set(7,n,1 builtins) comparision.
           While the order of elements does not matter, duplicate elements do.

       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(1,8) the same

       If you simply want to do a little tweaking of how the tests behave, you
       can access(2,5) the underlying Test::Builder object like so:

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

           Returns the Test::Builder object underlying Test::More for you to
           play with.

       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.

       Making your own ok()
           If you are trying to extend Test::More, don't.  Use Test::Builder

       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.

       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  As such, the names of
       the most common routines are kept tiny, special cases and magic(4,5) side-
       effects are kept to a minimum.  WYSIWYG.

       Test::Simple if(3,n) all this confuses you and you just want to write(1,2) 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

       Test::Unit describes a very featureful unit testing interface.

       Test::Inline shows the idea of embedded testing.

       SelfTest is another approach to embedded testing.

       Michael G Schwern <> 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 2001 by Michael G Schwern <>.

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


perl v5.8.5                       2001-09-21                     Test::More(3)

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