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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 AT pobox.com>

MAINTAINERS
    Chad Granum <exodist AT cpan.org>

COPYRIGHT
    Copyright 2002-2008 by chromatic <chromatic AT wgz.org> and Michael G Schwern <schwern AT 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

Test::Builder(3pm)
NAME SYNOPSIS DESCRIPTION
Construction Setting up tests Running tests Other Testing Methods Test building utility methods Test style Output Test Status and Info
EXIT CODES THREADS MEMORY EXAMPLES SEE ALSO AUTHORS MAINTAINERS COPYRIGHT

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