Provided by: perl-doc_5.36.0-7_all 
NAME
Test::Builder - Backend for building test libraries
SYNOPSIS
package My::Test::Module;
use base 'Test::Builder::Module';
my $CLASS = __PACKAGE__;
sub ok {
my($test, $name) = @_;
my $tb = $CLASS->builder;
$tb->ok($test, $name);
}
DESCRIPTION
Test::Simple and Test::More have proven to be popular testing modules, but they're not
always flexible enough. Test::Builder provides a building block upon which to write your
own test libraries which can work together.
Construction
new
my $Test = Test::Builder->new;
Returns a Test::Builder object representing the current state of the test.
Since you only run one test per program "new" always returns the same Test::Builder
object. No matter how many times you call "new()", you're getting the same object.
This is called a singleton. This is done so that multiple modules share such global
information as the test counter and where test output is going.
If you want a completely new Test::Builder object different from the singleton, use
"create".
create
my $Test = Test::Builder->create;
Ok, so there can be more than one Test::Builder object and this is how you get it.
You might use this instead of "new()" if you're testing a Test::Builder based module,
but otherwise you probably want "new".
NOTE: the implementation is not complete. "level", for example, is still shared by
all Test::Builder objects, even ones created using this method. Also, the method name
may change in the future.
subtest
$builder->subtest($name, \&subtests, @args);
See documentation of "subtest" in Test::More.
"subtest" also, and optionally, accepts arguments which will be passed to the subtests
reference.
name
diag $builder->name;
Returns the name of the current builder. Top level builders default to $0 (the name
of the executable). Child builders are named via the "child" method. If no name is
supplied, will be named "Child of $parent->name".
reset
$Test->reset;
Reinitializes the Test::Builder singleton to its original state. Mostly useful for
tests run in persistent environments where the same test might be run multiple times
in the same process.
Setting up tests
These methods are for setting up tests and declaring how many there are. You usually only
want to call one of these methods.
plan
$Test->plan('no_plan');
$Test->plan( skip_all => $reason );
$Test->plan( tests => $num_tests );
A convenient way to set up your tests. Call this and Test::Builder will print the
appropriate headers and take the appropriate actions.
If you call "plan()", don't call any of the other methods below.
expected_tests
my $max = $Test->expected_tests;
$Test->expected_tests($max);
Gets/sets the number of tests we expect this test to run and prints out the
appropriate headers.
no_plan
$Test->no_plan;
Declares that this test will run an indeterminate number of tests.
done_testing
$Test->done_testing();
$Test->done_testing($num_tests);
Declares that you are done testing, no more tests will be run after this point.
If a plan has not yet been output, it will do so.
$num_tests is the number of tests you planned to run. If a numbered plan was already
declared, and if this contradicts, a failing test will be run to reflect the planning
mistake. If "no_plan" was declared, this will override.
If "done_testing()" is called twice, the second call will issue a failing test.
If $num_tests is omitted, the number of tests run will be used, like no_plan.
"done_testing()" is, in effect, used when you'd want to use "no_plan", but safer.
You'd use it like so:
$Test->ok($a == $b);
$Test->done_testing();
Or to plan a variable number of tests:
for my $test (@tests) {
$Test->ok($test);
}
$Test->done_testing(scalar @tests);
has_plan
$plan = $Test->has_plan
Find out whether a plan has been defined. $plan is either "undef" (no plan has been
set), "no_plan" (indeterminate # of tests) or an integer (the number of expected
tests).
skip_all
$Test->skip_all;
$Test->skip_all($reason);
Skips all the tests, using the given $reason. Exits immediately with 0.
exported_to
my $pack = $Test->exported_to;
$Test->exported_to($pack);
Tells Test::Builder what package you exported your functions to.
This method isn't terribly useful since modules which share the same Test::Builder
object might get exported to different packages and only the last one will be honored.
Running tests
These actually run the tests, analogous to the functions in Test::More.
They all return true if the test passed, false if the test failed.
$name is always optional.
ok
$Test->ok($test, $name);
Your basic test. Pass if $test is true, fail if $test is false. Just like
Test::Simple's "ok()".
is_eq
$Test->is_eq($got, $expected, $name);
Like Test::More's "is()". Checks if "$got eq $expected". This is the string version.
"undef" only ever matches another "undef".
is_num
$Test->is_num($got, $expected, $name);
Like Test::More's "is()". Checks if "$got == $expected". This is the numeric
version.
"undef" only ever matches another "undef".
isnt_eq
$Test->isnt_eq($got, $dont_expect, $name);
Like Test::More's "isnt()". Checks if "$got ne $dont_expect". This is the string
version.
isnt_num
$Test->isnt_num($got, $dont_expect, $name);
Like Test::More's "isnt()". Checks if "$got ne $dont_expect". This is the numeric
version.
like
$Test->like($thing, qr/$regex/, $name);
$Test->like($thing, '/$regex/', $name);
Like Test::More's "like()". Checks if $thing matches the given $regex.
unlike
$Test->unlike($thing, qr/$regex/, $name);
$Test->unlike($thing, '/$regex/', $name);
Like Test::More's "unlike()". Checks if $thing does not match the given $regex.
cmp_ok
$Test->cmp_ok($thing, $type, $that, $name);
Works just like Test::More's "cmp_ok()".
$Test->cmp_ok($big_num, '!=', $other_big_num);
Other Testing Methods
These are methods which are used in the course of writing a test but are not themselves
tests.
BAIL_OUT
$Test->BAIL_OUT($reason);
Indicates to the Test::Harness that things are going so badly all testing should
terminate. This includes running any additional test scripts.
It will exit with 255.
skip
$Test->skip;
$Test->skip($why);
Skips the current test, reporting $why.
todo_skip
$Test->todo_skip;
$Test->todo_skip($why);
Like "skip()", only it will declare the test as failing and TODO. Similar to
print "not ok $tnum # TODO $why\n";
Test building utility methods
These methods are useful when writing your own test methods.
maybe_regex
$Test->maybe_regex(qr/$regex/);
$Test->maybe_regex('/$regex/');
This method used to be useful back when Test::Builder worked on Perls before 5.6 which
didn't have qr//. Now its pretty useless.
Convenience method for building testing functions that take regular expressions as
arguments.
Takes a quoted regular expression produced by "qr//", or a string representing a
regular expression.
Returns a Perl value which may be used instead of the corresponding regular
expression, or "undef" if its argument is not recognized.
For example, a version of "like()", sans the useful diagnostic messages, could be
written as:
sub laconic_like {
my ($self, $thing, $regex, $name) = @_;
my $usable_regex = $self->maybe_regex($regex);
die "expecting regex, found '$regex'\n"
unless $usable_regex;
$self->ok($thing =~ m/$usable_regex/, $name);
}
is_fh
my $is_fh = $Test->is_fh($thing);
Determines if the given $thing can be used as a filehandle.
Test style
level
$Test->level($how_high);
How far up the call stack should $Test look when reporting where the test failed.
Defaults to 1.
Setting $Test::Builder::Level overrides. This is typically useful localized:
sub my_ok {
my $test = shift;
local $Test::Builder::Level = $Test::Builder::Level + 1;
$TB->ok($test);
}
To be polite to other functions wrapping your own you usually want to increment $Level
rather than set it to a constant.
use_numbers
$Test->use_numbers($on_or_off);
Whether or not the test should output numbers. That is, this if true:
ok 1
ok 2
ok 3
or this if false
ok
ok
ok
Most useful when you can't depend on the test output order, such as when threads or
forking is involved.
Defaults to on.
no_diag
$Test->no_diag($no_diag);
If set true no diagnostics will be printed. This includes calls to "diag()".
no_ending
$Test->no_ending($no_ending);
Normally, Test::Builder does some extra diagnostics when the test ends. It also
changes the exit code as described below.
If this is true, none of that will be done.
no_header
$Test->no_header($no_header);
If set to true, no "1..N" header will be printed.
Output
Controlling where the test output goes.
It's ok for your test to change where STDOUT and STDERR point to, Test::Builder's default
output settings will not be affected.
diag
$Test->diag(@msgs);
Prints out the given @msgs. Like "print", arguments are simply appended together.
Normally, it uses the "failure_output()" handle, but if this is for a TODO test, the
"todo_output()" handle is used.
Output will be indented and marked with a # so as not to interfere with test output.
A newline will be put on the end if there isn't one already.
We encourage using this rather than calling print directly.
Returns false. Why? Because "diag()" is often used in conjunction with a failing
test ("ok() || diag()") it "passes through" the failure.
return ok(...) || diag(...);
note
$Test->note(@msgs);
Like "diag()", but it prints to the "output()" handle so it will not normally be seen
by the user except in verbose mode.
explain
my @dump = $Test->explain(@msgs);
Will dump the contents of any references in a human readable format. Handy for things
like...
is_deeply($have, $want) || diag explain $have;
or
is_deeply($have, $want) || note explain $have;
output
failure_output
todo_output
my $filehandle = $Test->output;
$Test->output($filehandle);
$Test->output($filename);
$Test->output(\$scalar);
These methods control where Test::Builder will print its output. They take either an
open $filehandle, a $filename to open and write to or a $scalar reference to append
to. It will always return a $filehandle.
output is where normal "ok/not ok" test output goes.
Defaults to STDOUT.
failure_output is where diagnostic output on test failures and "diag()" goes. It is
normally not read by Test::Harness and instead is displayed to the user.
Defaults to STDERR.
"todo_output" is used instead of "failure_output()" for the diagnostics of a failing
TODO test. These will not be seen by the user.
Defaults to STDOUT.
reset_outputs
$tb->reset_outputs;
Resets all the output filehandles back to their defaults.
carp
$tb->carp(@message);
Warns with @message but the message will appear to come from the point where the
original test function was called ("$tb->caller").
croak
$tb->croak(@message);
Dies with @message but the message will appear to come from the point where the
original test function was called ("$tb->caller").
Test Status and Info
no_log_results
This will turn off result long-term storage. Calling this method will make "details"
and "summary" useless. You may want to use this if you are running enough tests to
fill up all available memory.
Test::Builder->new->no_log_results();
There is no way to turn it back on.
current_test
my $curr_test = $Test->current_test;
$Test->current_test($num);
Gets/sets the current test number we're on. You usually shouldn't have to set this.
If set forward, the details of the missing tests are filled in as 'unknown'. if set
backward, the details of the intervening tests are deleted. You can erase history if
you really want to.
is_passing
my $ok = $builder->is_passing;
Indicates if the test suite is currently passing.
More formally, it will be false if anything has happened which makes it impossible for
the test suite to pass. True otherwise.
For example, if no tests have run "is_passing()" will be true because even though a
suite with no tests is a failure you can add a passing test to it and start passing.
Don't think about it too much.
summary
my @tests = $Test->summary;
A simple summary of the tests so far. True for pass, false for fail. This is a
logical pass/fail, so todos are passes.
Of course, test #1 is $tests[0], etc...
details
my @tests = $Test->details;
Like "summary()", but with a lot more detail.
$tests[$test_num - 1] =
{ 'ok' => is the test considered a pass?
actual_ok => did it literally say 'ok'?
name => name of the test (if any)
type => type of test (if any, see below).
reason => reason for the above (if any)
};
'ok' is true if Test::Harness will consider the test to be a pass.
'actual_ok' is a reflection of whether or not the test literally printed 'ok' or 'not
ok'. This is for examining the result of 'todo' tests.
'name' is the name of the test.
'type' indicates if it was a special test. Normal tests have a type of ''. Type can
be one of the following:
skip see skip()
todo see todo()
todo_skip see todo_skip()
unknown see below
Sometimes the Test::Builder test counter is incremented without it printing any test
output, for example, when "current_test()" is changed. In these cases, Test::Builder
doesn't know the result of the test, so its type is 'unknown'. These details for
these tests are filled in. They are considered ok, but the name and actual_ok is left
"undef".
For example "not ok 23 - hole count # TODO insufficient donuts" would result in this
structure:
$tests[22] = # 23 - 1, since arrays start from 0.
{ ok => 1, # logically, the test passed since its todo
actual_ok => 0, # in absolute terms, it failed
name => 'hole count',
type => 'todo',
reason => 'insufficient donuts'
};
todo
my $todo_reason = $Test->todo;
my $todo_reason = $Test->todo($pack);
If the current tests are considered "TODO" it will return the reason, if any. This
reason can come from a $TODO variable or the last call to "todo_start()".
Since a TODO test does not need a reason, this function can return an empty string
even when inside a TODO block. Use "$Test->in_todo" to determine if you are currently
inside a TODO block.
"todo()" is about finding the right package to look for $TODO in. It's pretty good at
guessing the right package to look at. It first looks for the caller based on "$Level
+ 1", since "todo()" is usually called inside a test function. As a last resort it
will use "exported_to()".
Sometimes there is some confusion about where "todo()" should be looking for the $TODO
variable. If you want to be sure, tell it explicitly what $pack to use.
find_TODO
my $todo_reason = $Test->find_TODO();
my $todo_reason = $Test->find_TODO($pack);
Like "todo()" but only returns the value of $TODO ignoring "todo_start()".
Can also be used to set $TODO to a new value while returning the old value:
my $old_reason = $Test->find_TODO($pack, 1, $new_reason);
in_todo
my $in_todo = $Test->in_todo;
Returns true if the test is currently inside a TODO block.
todo_start
$Test->todo_start();
$Test->todo_start($message);
This method allows you declare all subsequent tests as TODO tests, up until the
"todo_end" method has been called.
The "TODO:" and $TODO syntax is generally pretty good about figuring out whether or
not we're in a TODO test. However, often we find that this is not possible to
determine (such as when we want to use $TODO but the tests are being executed in other
packages which can't be inferred beforehand).
Note that you can use this to nest "todo" tests
$Test->todo_start('working on this');
# lots of code
$Test->todo_start('working on that');
# more code
$Test->todo_end;
$Test->todo_end;
This is generally not recommended, but large testing systems often have weird internal
needs.
We've tried to make this also work with the TODO: syntax, but it's not guaranteed and
its use is also discouraged:
TODO: {
local $TODO = 'We have work to do!';
$Test->todo_start('working on this');
# lots of code
$Test->todo_start('working on that');
# more code
$Test->todo_end;
$Test->todo_end;
}
Pick one style or another of "TODO" to be on the safe side.
"todo_end"
$Test->todo_end;
Stops running tests as "TODO" tests. This method is fatal if called without a
preceding "todo_start" method call.
caller
my $package = $Test->caller;
my($pack, $file, $line) = $Test->caller;
my($pack, $file, $line) = $Test->caller($height);
Like the normal "caller()", except it reports according to your "level()".
$height will be added to the "level()".
If "caller()" winds up off the top of the stack it report the highest context.
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.
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.
THREADS
In perl 5.8.1 and later, Test::Builder is thread-safe. The test number is shared by all
threads. This means if one thread sets the test number using "current_test()" they will
all be effected.
While versions earlier than 5.8.1 had threads they contain too many bugs to support.
Test::Builder is only thread-aware if threads.pm is loaded before Test::Builder.
You can directly disable thread support with one of the following:
$ENV{T2_NO_IPC} = 1
or
no Test2::IPC;
or
Test2::API::test2_ipc_disable()
MEMORY
An informative hash, accessible via "details()", is stored for each test you perform. So
memory usage will scale linearly with each test run. Although this is not a problem for
most test suites, it can become an issue if you do large (hundred thousands to million)
combinatorics tests in the same run.
In such cases, you are advised to either split the test file into smaller ones, or use a
reverse approach, doing "normal" (code) compares and triggering "fail()" should anything
go unexpected.
Future versions of Test::Builder will have a way to turn history off.
EXAMPLES
CPAN can provide the best examples. Test::Simple, Test::More, Test::Exception and
Test::Differences all use Test::Builder.
SEE ALSO
INTERNALS
Test2, Test2::API
LEGACY
Test::Simple, Test::More
EXTERNAL
Test::Harness
AUTHORS
Original code by chromatic, maintained by Michael G Schwern <schwern@pobox.com>
MAINTAINERS
Chad Granum <exodist@cpan.org>
COPYRIGHT
Copyright 2002-2008 by chromatic <chromatic@wgz.org> and
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