=head1 NAME

Test::Harness::TAP - Documentation for the TAP format

=head1 SYNOPSIS

TAP, the Test Anything Protocol, is Perl's simple text-based interface
between testing modules such as Test::More and the test harness
Test::Harness.

=head1 TODO

Exit code of the process.

=head1 THE TAP FORMAT

TAP's general format is:

    1..N
    ok 1 Description # Directive
    # Diagnostic
    ....
    ok 47 Description
    ok 48 Description
    more tests....

For example, a test file's output might look like:

    1..4
    ok 1 - Input file opened
    not ok 2 - First line of the input valid
    ok 3 - Read the rest of the file
    not ok 4 - Summarized correctly # TODO Not written yet

=head1 HARNESS BEHAVIOR

In this document, the "harness" is any program analyzing TAP output.
Typically this will be Perl's I<prove> program, or the underlying
C<Test::Harness::runtests> subroutine.

A harness must only read TAP output from standard output and not
from standard error.  Lines written to standard output matching
C</^(not )?ok\b/> must be interpreted as test lines.  All other
lines must not be considered test output.

=head1 TESTS LINES AND THE PLAN

=head2 The plan

The plan tells how many tests will be run, or how many tests have
run.  It's a check that the test file hasn't stopped prematurely.
It must appear once, whether at the beginning or end of the output.

The plan is usually the first line of TAP output and it specifies how
many test points are to follow. For example,

    1..10

means you plan on running 10 tests. This is a safeguard in case your test
file dies silently in the middle of its run.  The plan is optional but if
there is a plan before the test points it must be the first non-diagnostic
line output by the test file.

In certain instances a test file may not know how many test points
it will ultimately be running. In this case the plan can be the last
non-diagnostic line in the output.

The plan cannot appear in the middle of the output, nor can it appear more
than once.

=head2 The test line

The core of TAP is the test line.  A test file prints one test line test
point executed. There must be at least one test line in TAP output. Each
test line comprises the following elements:

=over 4

=item * C<ok> or C<not ok>

This tells whether the test point passed or failed. It must be
at the beginning of the line. C</^not ok/> indicates a failed test
point. C</^ok/> is a successful test point. This is the only mandatory
part of the line.

Note that unlike the Directives below, C<ok> and C<not ok> are
case-sensitive.

=item * Test number

TAP expects the C<ok> or C<not ok> to be followed by a test point
number. If there is no number the harness must maintain
its own counter until the script supplies test numbers again. So
the following test output

    1..6
    not ok
    ok
    not ok
    ok
    ok

has five tests.  The sixth is missing.  Test::Harness will generate

    FAILED tests 1, 3, 6
    Failed 3/6 tests, 50.00% okay

=item * Description

Any text after the test number but before a C<#> is the description of
the test point.

    ok 42 this is the description of the test

Descriptions should not begin with a digit so that they are not confused
with the test point number.

The harness may do whatever it wants with the description.

=item * Directive

The test point may include a directive, following a hash on the
test line.  There are currently two directives allowed: C<TODO> and
C<SKIP>.  These are discussed below.

=back

To summarize:

=over 4

=item * ok/not ok (required)

=item * Test number (recommended)

=item * Description (recommended)

=item * Directive (only when necessary)

=back

=head1 DIRECTIVES

Directives are special notes that follow a C<#> on the test line.
Only two are currently defined: C<TODO> and C<SKIP>.  Note that
these two keywords are not case-sensitive.

=head2 TODO tests

If the directive starts with C<# TODO>, the test is counted as a
todo test, and the text after C<TODO> is the the explanation.

    not ok 13 # TODO bend space and time

Note that if the TODO has an explanation it must be separated from
C<TODO> by a space.

These tests represent a feature to be implemented or a bug to be fixed
and act as something of an executable "things to do" list.  They are
B<not> expected to succeed.  Should a todo test point begin succeeding,
the harness should report it as a bonus.  This indicates that whatever
you were supposed to do has been done and you should promote this to a
normal test point.

=head2 Skipping tests

If the directive starts with C<# SKIP>, the test is counted as having
been skipped.  If the whole test file succeeds, the count of skipped
tests is included in the generated output.  The harness should report
the text after C< # SKIP\S*\s+> as a reason for skipping.

    ok 23 # skip Insufficient flogiston pressure.

Similarly, one can include an explanation in a plan line,
emitted if the test file is skipped completely:

    1..0 # Skipped: WWW::Mechanize not installed

=head1 OTHER LINES

=head2 Bail out!

As an emergency measure a test script can decide that further tests
are useless (e.g. missing dependencies) and testing should stop
immediately. In that case the test script prints the magic words

    Bail out!

to standard output. Any message after these words must be displayed
by the interpreter as the reason why testing must be stopped, as
in

    Bail out! MySQL is not running.

=head2 Diagnostics

Additional information may be put into the testing output on separate
lines.  Diagnostic lines should begin with a C<#>, which the harness must
ignore, at least as far as analyzing the test results.  The harness is
free, however, to display the diagnostics.  Typically diagnostics are
used to provide information about the environment in which test file is
running, or to delineate a group of tests.
    ...
    ok 18 - Closed database connection
    # End of database section.
    # This starts the network part of the test.
    # Daemon started on port 2112
    ok 19 - Opened socket
    ...
    ok 47 - Closed socket
    # End of network tests

=head2 Anything else

Any output line that is not a plan, a test line or a diagnostic is
incorrect.  How a harness handles the incorrect line is undefined.
Test::Harness silently ignores incorrect lines, but will become more
stringent in the future.

=head1 EXAMPLES

All names, places, and events depicted in any example are wholly
fictitious and bear no resemblance to, connection with, or relation to any
real entity. Any such similarity is purely coincidental, unintentional,
and unintended.

=head2 Common with explanation

The following TAP listing declares that six tests follow as well as
provides handy feedback as to what the test is about to do. All six
tests pass.

    1..6
    #
    # Create a new Board and Tile, then place
    # the Tile onto the board.
    #
    ok 1 - The object isa Board
    ok 2 - Board size is zero
    ok 3 - The object isa Tile
    ok 4 - Get possible places to put the Tile
    ok 5 - Placing the tile produces no error
    ok 6 - Board size is 1

=head2 Unknown amount and failures

This hypothetical test program ensures that a handful of servers are
online and network-accessible. Because it retrieves the hypothetical
servers from a database, it doesn't know exactly how many servers it
will need to ping. Thus, the test count is declared at the bottom after
all the test points have run. Also, two of the tests fail.

    ok 1 - retrieving servers from the database
    # need to ping 6 servers
    ok 2 - pinged diamond
    ok 3 - pinged ruby
    not ok 4 - pinged saphire
    ok 5 - pinged onyx
    not ok 6 - pinged quartz
    ok 7 - pinged gold
    1..7

=head2 Giving up

This listing reports that a pile of tests are going to be run. However,
the first test fails, reportedly because a connection to the database
could not be established. The program decided that continuing was
pointless and exited.

    1..573
    not ok 1 - database handle
    Bail out! Couldn't connect to database.

=head2 Skipping a few

The following listing plans on running 5 tests. However, our program
decided to not run tests 2 thru 5 at all. To properly report this,
the tests are marked as being skipped.

    1..5
    ok 1 - approved operating system
    # $^0 is solaris
    ok 2 - # SKIP no /sys directory
    ok 3 - # SKIP no /sys directory
    ok 4 - # SKIP no /sys directory
    ok 5 - # SKIP no /sys directory

=head2 Skipping everything

This listing shows that the entire listing is a skip. No tests were run.

    1..0 # skip because English-to-French translator isn't installed

=head2 Got spare tuits?

The following example reports that four tests are run and the last two
tests failed. However, becauses the failing tests are marked as things
to do later, they are considered successes. Thus, a harness should report
this entire listing as a success.

    1..4
    ok 1 - Creating test program
    ok 2 - Test program runs, no error
    not ok 3 - infinite loop # TODO halting problem unsolved
    not ok 4 - infinite loop 2 # TODO halting problem unsolved

=head2 Creative liberties

This listing shows an alternate output where the test numbers aren't
provided. The test also reports the state of a ficticious board game in
diagnostic form. Finally, the test count is reported at the end.

    ok - created Board
    ok
    ok
    ok
    ok
    ok
    ok
    ok
    # +------+------+------+------+
    # |      |16G   |      |05C   |
    # |      |G N C |      |C C G |
    # |      |  G   |      |  C  +|
    # +------+------+------+------+
    # |10C   |01G   |      |03C   |
    # |R N G |G A G |      |C C C |
    # |  R   |  G   |      |  C  +|
    # +------+------+------+------+
    # |      |01G   |17C   |00C   |
    # |      |G A G |G N R |R N R |
    # |      |  G   |  R   |  G   |
    # +------+------+------+------+
    ok - board has 7 tiles + starter tile
    1..9

=head1 AUTHORS

Andy Lester, based on the original Test::Harness documentation by Michael Schwern.

=head1 ACKNOWLEDGEMENTS

Thanks to
Pete Krawczyk,
Paul Johnson,
Ian Langworth
and Nik Clayton
for help and contributions on this document.

The basis for the TAP format was created by Larry Wall in the
original test script for Perl 1.  Tim Bunce and Andreas Koenig
developed it further with their modifications to Test::Harness.

=head1 COPYRIGHT

Copyright 2003-2005 by
Michael G Schwern C<< <schwern@pobox.com> >>,
Andy Lester C<< <andy@petdance.com> >>.

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

See L<http://www.perl.com/perl/misc/Artistic.html>.

=cut
