Document makepatch in Porting/patching

[p5sagit/p5-mst-13.2.git] / lib / Test / Harness.pm

# -*- Mode: cperl; cperl-indent-level: 4 -*-
package Test::Harness;

use 5.005_64;
use Exporter;
use Benchmark;
use Config;
use strict;

our($VERSION, $Verbose, $Switches, $Have_Devel_Corestack, $Curtest,
    $Columns, $verbose, $switches,
    @ISA, @EXPORT, @EXPORT_OK
   );

# Backwards compatibility for exportable variable names.
*verbose  = \$Verbose;
*switches = \$Switches;

$Have_Devel_Corestack = 0;

$VERSION = "1.1702";

$ENV{HARNESS_ACTIVE} = 1;

# Some experimental versions of OS/2 build have broken $?
my $Ignore_Exitcode = $ENV{HARNESS_IGNORE_EXITCODE};

my $Files_In_Dir = $ENV{HARNESS_FILELEAK_IN_DIR};


@ISA = ('Exporter');
@EXPORT    = qw(&runtests);
@EXPORT_OK = qw($verbose $switches);

$Verbose  = 0;
$Switches = "-w";
$Columns  = $ENV{HARNESS_COLUMNS} || $ENV{COLUMNS} || 80;


sub globdir { opendir DIRH, shift; my @f = readdir DIRH; closedir DIRH; @f }

sub runtests {
    my(@tests) = @_;

    my($tot, $failedtests) = _runtests(@tests);
    _show_results($tot, $failedtests);

    return ($tot->{bad} == 0 && $tot->{max}) ;
}


sub _runtests {
    my(@tests) = @_;
    local($|) = 1;
    my(%failedtests);

    # Test-wide totals.
    my(%tot) = (
                bonus    => 0,
                max      => 0,
                ok       => 0,
                files    => 0,
                bad      => 0,
                good     => 0,
                tests    => scalar @tests,
                sub_skipped  => 0,
                skipped  => 0,
                bench    => 0
               );

    # pass -I flags to children
    my $old5lib = $ENV{PERL5LIB};

    # VMS has a 255-byte limit on the length of %ENV entries, so
    # toss the ones that involve perl_root, the install location
    # for VMS
    my $new5lib;
    if ($^O eq 'VMS') {
	$new5lib = join($Config{path_sep}, grep {!/perl_root/i;} @INC);
	$Switches =~ s/-(\S*[A-Z]\S*)/"-$1"/g;
    }
    else {
        $new5lib = join($Config{path_sep}, @INC);
    }

    local($ENV{'PERL5LIB'}) = $new5lib;

    my @dir_files = globdir $Files_In_Dir if defined $Files_In_Dir;
    my $t_start = new Benchmark;

    foreach my $test (@tests) {
	my $te = $test;
	chop($te);      # XXX chomp?

	if ($^O eq 'VMS') { $te =~ s/^.*\.t\./[.t./s; }
	my $blank = (' ' x 77);
	my $leader = "$te" . '.' x (20 - length($te));
	my $ml = "";
	$ml = "\r$blank\r$leader"
	    if -t STDOUT and not $ENV{HARNESS_NOTTY} and not $Verbose;
	print $leader;

         my $s = _set_switches($test);

	my $cmd = ($ENV{'HARNESS_COMPILE_TEST'})
		? "./perl -I../lib ../utils/perlcc $test "
		  . "-run 2>> ./compilelog |" 
		: "$^X $s $test|";
	$cmd = "MCR $cmd" if $^O eq 'VMS';
	open(my $fh, $cmd) or print "can't run $test. $!\n";

        # state of the current test.
        my %test = (
                    ok          => 0,
                    next        => 0,
                    max         => 0,
                    failed      => [],
                    todo        => {},
                    bonus       => 0,
                    skipped     => 0,
                    skip_reason => undef,
                    ml          => $ml,
                   );

        my($seen_header, $tests_seen) = (0,0);
	while (<$fh>) {
            if( _parse_header($_, \%test, \%tot) ) {
                warn "Test header seen twice!\n" if $seen_header;

                $seen_header = 1;

                warn "1..M can only appear at the beginning or end of tests\n"
                  if $tests_seen && $test{max} < $tests_seen;
            }
            elsif( _parse_test_line($_, \%test, \%tot) ) {
                $tests_seen++;
            }
            # else, ignore it.
	}

        my($estatus, $wstatus) = _close_fh($fh);

	if ($wstatus) {
            $failedtests{$test} = _dubious_return(\%test, \%tot, 
                                                  $estatus, $wstatus);
	}
        elsif ($test{ok} == $test{max} && $test{next} == $test{max}+1) {
	    if ($test{max} and $test{skipped} + $test{bonus}) {
		my @msg;
		push(@msg, "$test{skipped}/$test{max} skipped: $test{skip_reason}")
		    if $test{skipped};
		push(@msg, "$test{bonus}/$test{max} unexpectedly succeeded")
		    if $test{bonus};
		print "$test{ml}ok, ".join(', ', @msg)."\n";
	    } elsif ($test{max}) {
		print "$test{ml}ok\n";
	    } elsif (defined $test{skip_reason}) {
		print "skipped: $test{skip_reason}\n";
		$tot{skipped}++;
	    } else {
		print "skipped test on this platform\n";
		$tot{skipped}++;
	    }
	    $tot{good}++;
	} elsif ($test{max}) {
	    if ($test{next} <= $test{max}) {
		push @{$test{failed}}, $test{next}..$test{max};
	    }
	    if (@{$test{failed}}) {
		my ($txt, $canon) = canonfailed($test{max},$test{skipped},
                                                @{$test{failed}});
		print "$test{ml}$txt";
		$failedtests{$test} = { canon   => $canon,
                                        max     => $test{max},
					failed  => scalar @{$test{failed}},
					name    => $test, 
                                        percent => 100*(scalar @{$test{failed}})/$test{max},
					estat   => '',
                                        wstat   => '',
				      };
	    } else {
		print "Don't know which tests failed: got $test{ok} ok, ".
                      "expected $test{max}\n";
		$failedtests{$test} = { canon   => '??',
                                        max     => $test{max},
					failed  => '??',
					name    => $test, 
                                        percent => undef,
					estat   => '', 
                                        wstat   => '',
				      };
	    }
	    $tot{bad}++;
	} elsif ($test{next} == 0) {
	    print "FAILED before any test output arrived\n";
	    $tot{bad}++;
	    $failedtests{$test} = { canon       => '??',
                                    max         => '??',
				    failed      => '??',
				    name        => $test,
                                    percent     => undef,
				    estat       => '', 
                                    wstat       => '',
				  };
	}
	$tot{sub_skipped} += $test{skipped};

	if (defined $Files_In_Dir) {
	    my @new_dir_files = globdir $Files_In_Dir;
	    if (@new_dir_files != @dir_files) {
		my %f;
		@f{@new_dir_files} = (1) x @new_dir_files;
		delete @f{@dir_files};
		my @f = sort keys %f;
		print "LEAKED FILES: @f\n";
		@dir_files = @new_dir_files;
	    }
	}
    }
    $tot{bench} = timediff(new Benchmark, $t_start);

    if ($^O eq 'VMS') {
	if (defined $old5lib) {
	    $ENV{PERL5LIB} = $old5lib;
	} else {
	    delete $ENV{PERL5LIB};
	}
    }

    return(\%tot, \%failedtests);
}


sub _show_results {
    my($tot, $failedtests) = @_;

    my $pct;
    my $bonusmsg = _bonusmsg($tot);

    if ($tot->{bad} == 0 && $tot->{max}) {
	print "All tests successful$bonusmsg.\n";
    } elsif ($tot->{tests}==0){
	die "FAILED--no tests were run for some reason.\n";
    } elsif ($tot->{max} == 0) {
	my $blurb = $tot->{tests}==1 ? "script" : "scripts";
	die "FAILED--$tot->{tests} test $blurb could be run, ".
            "alas--no output ever seen\n";
    } else {
	$pct = sprintf("%.2f", $tot->{good} / $tot->{tests} * 100);
	my $subpct = sprintf " %d/%d subtests failed, %.2f%% okay.",
	                      $tot->{max} - $tot->{ok}, $tot->{max}, 
                              100*$tot->{ok}/$tot->{max};

        my($fmt_top, $fmt) = _create_fmts($failedtests);

	# Now write to formats
	for my $script (sort keys %$failedtests) {
	  $Curtest = $failedtests->{$script};
	  write;
	}
	if ($tot->{bad}) {
	    $bonusmsg =~ s/^,\s*//;
	    print "$bonusmsg.\n" if $bonusmsg;
	    die "Failed $tot->{bad}/$tot->{tests} test scripts, $pct% okay.".
                "$subpct\n";
	}
    }

    printf("Files=%d, Tests=%d, %s\n",
           $tot->{files}, $tot->{max}, timestr($tot->{bench}, 'nop'));
}


sub _parse_header {
    my($line, $test, $tot) = @_;

    my $is_header = 0;

    print $line if $Verbose;

    # 1..10 todo 4 7 10;
    if ($line =~ /^1\.\.([0-9]+) todo([\d\s]+);?/i) {
        $test->{max} = $1;
        for (split(/\s+/, $2)) { $test->{todo}{$_} = 1; }

        $tot->{max} += $test->{max};
        $tot->{files}++;

        $is_header = 1;
    }
    # 1..10
    # 1..0 # skip  Why?  Because I said so!
    elsif ($line =~ /^1\.\.([0-9]+)
                      (\s*\#\s*[Ss]kip\S*(?>\s+) (.+))?
                    /x
          )
    {
        $test->{max} = $1;
        $tot->{max} += $test->{max};
        $tot->{files}++;
        $test->{next} = 1 unless $test->{next};
        $test->{skip_reason} = $3 if not $test->{max} and defined $3;

        $is_header = 1;
    }
    else {
        $is_header = 0;
    }

    return $is_header;
}


sub _parse_test_line {
    my($line, $test, $tot) = @_;

    if ($line =~ /^(not\s+)?ok\b/i) {
        my $this = $test->{next} || 1;
        # "not ok 23"
        if ($line =~ /^not ok\s*(\d*)/){         # test failed
            $this = $1 if length $1 and $1 > 0;
            print "$test->{ml}NOK $this" if $test->{ml};
            if (!$test->{todo}{$this}) {
                push @{$test->{failed}}, $this;
            } else {
                $test->{ok}++;
                $tot->{ok}++;
            }
        }
        # "ok 23 # skip (you're not cleared for that)"
        elsif ($line =~ /^ok\s*(\d*)\ *
                         (\s*\#\s*[Ss]kip\S*(?:(?>\s+)(.+))?)?
                        /x)        # test skipped
        {
            $this = $1 if length $1 and $1 > 0;
            print "$test->{ml}ok $this/$test->{max}" if $test->{ml};
            $test->{ok}++;
            $tot->{ok}++;
            $test->{skipped}++ if defined $2;
            my $reason;
            $reason = 'unknown reason' if defined $2;
            $reason = $3 if defined $3;
            if (defined $reason and defined $test->{skip_reason}) {
                # print "was: '$skip_reason' new '$reason'\n";
                $test->{skip_reason} = 'various reasons'
                  if $test->{skip_reason} ne $reason;
            } elsif (defined $reason) {
                $test->{skip_reason} = $reason;
            }
            $test->{bonus}++, $tot->{bonus}++ if $test->{todo}{$this};
        }
        # XXX ummm... dunno
        elsif ($line =~ /^ok\s*(\d*)\s*\#([^\r]*)$/) { # XXX multiline ok?
            $this = $1 if $1 > 0;
            print "$test->{ml}ok $this/$test->{max}" if $test->{ml};
            $test->{ok}++;
            $tot->{ok}++;
        }
        else {
            # an ok or not ok not matching the 3 cases above...
            # just ignore it for compatibility with TEST
            next;
        }

        if ($this > $test->{next}) {
            # print "Test output counter mismatch [test $this]\n";
            # no need to warn probably
            push @{$test->{failed}}, $test->{next}..$this-1;
        }
        elsif ($this < $test->{next}) {
            #we have seen more "ok" lines than the number suggests
            print "Confused test output: test $this answered after ".
                  "test ", $test->{next}-1, "\n";
            $test->{next} = $this;
        }
        $test->{next} = $this + 1;

    }
    elsif ($line =~ /^Bail out!\s*(.*)/i) { # magic words
        die "FAILED--Further testing stopped" .
            ($1 ? ": $1\n" : ".\n");
    }
}


sub _bonusmsg {
    my($tot) = @_;

    my $bonusmsg = '';
    $bonusmsg = (" ($tot->{bonus} subtest".($tot->{bonus} > 1 ? 's' : '').
	       " UNEXPECTEDLY SUCCEEDED)")
	if $tot->{bonus};

    if ($tot->{skipped}) {
	$bonusmsg .= ", $tot->{skipped} test"
                     . ($tot->{skipped} != 1 ? 's' : '');
	if ($tot->{sub_skipped}) {
	    $bonusmsg .= " and $tot->{sub_skipped} subtest"
			 . ($tot->{sub_skipped} != 1 ? 's' : '');
	}
	$bonusmsg .= ' skipped';
    }
    elsif ($tot->{sub_skipped}) {
	$bonusmsg .= ", $tot->{sub_skipped} subtest"
	             . ($tot->{sub_skipped} != 1 ? 's' : '')
		     . " skipped";
    }

    return $bonusmsg;
}

# VMS has some subtle nastiness with closing the test files.
sub _close_fh {
    my($fh) = shift;

    close($fh); # must close to reap child resource values

    my $wstatus = $Ignore_Exitcode ? 0 : $?;	# Can trust $? ?
    my $estatus;
    $estatus = ($^O eq 'VMS'
                  ? eval 'use vmsish "status"; $estatus = $?'
                  : $wstatus >> 8);

    return($estatus, $wstatus);
}


# Set up the command-line switches to run perl as.
sub _set_switches {
    my($test) = shift;

    open(my $fh, $test) or print "can't open $test. $!\n";
    my $first = <$fh>;
    my $s = $Switches;
    $s .= " $ENV{'HARNESS_PERL_SWITCHES'}"
      if exists $ENV{'HARNESS_PERL_SWITCHES'};
    $s .= join " ", q[ "-T"], map {qq["-I$_"]} @INC
      if $first =~ /^#!.*\bperl.*-\w*T/;

    close($fh) or print "can't close $test. $!\n";

    return $s;
}


# Test program go boom.
sub _dubious_return {
    my($test, $tot, $estatus, $wstatus) = @_;
    my ($failed, $canon, $percent) = ('??', '??');

    printf "$test->{ml}dubious\n\tTest returned status $estatus ".
           "(wstat %d, 0x%x)\n",
           $wstatus,$wstatus;
    print "\t\t(VMS status is $estatus)\n" if $^O eq 'VMS';

    if (corestatus($wstatus)) { # until we have a wait module
        if ($Have_Devel_Corestack) {
            Devel::CoreStack::stack($^X);
        } else {
            print "\ttest program seems to have generated a core\n";
        }
    }

    $tot->{bad}++;

    if ($test->{max}) {
        if ($test->{next} == $test->{max} + 1 and not @{$test->{failed}}) {
            print "\tafter all the subtests completed successfully\n";
            $percent = 0;
            $failed = 0;	# But we do not set $canon!
        }
        else {
            push @{$test->{failed}}, $test->{next}..$test->{max};
            $failed = @{$test->{failed}};
            (my $txt, $canon) = canonfailed($test->{max},$test->{skipped},@{$test->{failed}});
            $percent = 100*(scalar @{$test->{failed}})/$test->{max};
            print "DIED. ",$txt;
        }
    }

    return { canon => $canon,  max => $test->{max} || '??',
             failed => $failed, 
             name => $test, percent => $percent,
             estat => $estatus, wstat => $wstatus,
           };
}


sub _garbled_output {
    my($gibberish) = shift;
    warn "Confusing test output:  '$gibberish'\n";
}


sub _create_fmts {
    my($failedtests) = @_;

    my $failed_str = "Failed Test";
    my $middle_str = " Status Wstat Total Fail  Failed  ";
    my $list_str = "List of Failed";

    # Figure out our longest name string for formatting purposes.
    my $max_namelen = length($failed_str);
    foreach my $script (keys %$failedtests) {
        my $namelen = length $failedtests->{$script}->{name};
        $max_namelen = $namelen if $namelen > $max_namelen;
    }

    my $list_len = $Columns - length($middle_str) - $max_namelen;
    if ($list_len < length($list_str)) {
        $list_len = length($list_str);
        $max_namelen = $Columns - length($middle_str) - $list_len;
        if ($max_namelen < length($failed_str)) {
            $max_namelen = length($failed_str);
            $Columns = $max_namelen + length($middle_str) + $list_len;
        }
    }

    my $fmt_top = "format STDOUT_TOP =\n"
                  . sprintf("%-${max_namelen}s", $failed_str)
                  . $middle_str
		  . $list_str . "\n"
		  . "-" x $Columns
		  . "\n.\n";

    my $fmt = "format STDOUT =\n"
	      . "@" . "<" x ($max_namelen - 1)
              . "	 @>> @>>>> @>>>> @>>> ^##.##%  "
	      . "^" . "<" x ($list_len - 1) . "\n"
	      . '{ $Curtest->{name}, $Curtest->{estat},'
	      . '  $Curtest->{wstat}, $Curtest->{max},'
	      . '  $Curtest->{failed}, $Curtest->{percent},'
	      . '  $Curtest->{canon}'
	      . "\n}\n"
	      . "~~" . " " x ($Columns - $list_len - 2) . "^"
	      . "<" x ($list_len - 1) . "\n"
	      . '$Curtest->{canon}'
	      . "\n.\n";

    eval $fmt_top;
    die $@ if $@;
    eval $fmt;
    die $@ if $@;

    return($fmt_top, $fmt);
}


my $tried_devel_corestack;
sub corestatus {
    my($st) = @_;

    eval {require 'wait.ph'};
    my $ret = defined &WCOREDUMP ? WCOREDUMP($st) : $st & 0200;

    eval { require Devel::CoreStack; $Have_Devel_Corestack++ } 
      unless $tried_devel_corestack++;

    $ret;
}

sub canonfailed ($@) {
    my($max,$skipped,@failed) = @_;
    my %seen;
    @failed = sort {$a <=> $b} grep !$seen{$_}++, @failed;
    my $failed = @failed;
    my @result = ();
    my @canon = ();
    my $min;
    my $last = $min = shift @failed;
    my $canon;
    if (@failed) {
	for (@failed, $failed[-1]) { # don't forget the last one
	    if ($_ > $last+1 || $_ == $last) {
		if ($min == $last) {
		    push @canon, $last;
		} else {
		    push @canon, "$min-$last";
		}
		$min = $_;
	    }
	    $last = $_;
	}
	local $" = ", ";
	push @result, "FAILED tests @canon\n";
	$canon = "@canon";
    } else {
	push @result, "FAILED test $last\n";
	$canon = $last;
    }

    push @result, "\tFailed $failed/$max tests, ";
    push @result, sprintf("%.2f",100*(1-$failed/$max)), "% okay";
    my $ender = 's' x ($skipped > 1);
    my $good = $max - $failed - $skipped;
    my $goodper = sprintf("%.2f",100*($good/$max));
    push @result, " (-$skipped skipped test$ender: $good okay, ".
                  "$goodper%)"
         if $skipped;
    push @result, "\n";
    my $txt = join "", @result;
    ($txt, $canon);
}

1;
__END__

=head1 NAME

Test::Harness - run perl standard test scripts with statistics

=head1 SYNOPSIS

use Test::Harness;

runtests(@tests);

=head1 DESCRIPTION

(By using the Test module, you can write test scripts without
knowing the exact output this module expects.  However, if you need to
know the specifics, read on!)

Perl test scripts print to standard output C<"ok N"> for each single
test, where C<N> is an increasing sequence of integers. The first line
output by a standard test script is C<"1..M"> with C<M> being the
number of tests that should be run within the test
script. Test::Harness::runtests(@tests) runs all the testscripts
named as arguments and checks standard output for the expected
C<"ok N"> strings.

After all tests have been performed, runtests() prints some
performance statistics that are computed by the Benchmark module.

=head2 The test script output

=over 4

=item B<1..M>

This header tells how many tests there will be.  It should be the
first line output by your test program (but its okay if its preceded
by comments).

In certain instanced, you may not know how many tests you will
ultimately be running.  In this case, it is permitted (but not
encouraged) for the 1..M header to appear as the B<last> line output
by your test (again, it can be followed by further comments).  But we
strongly encourage you to put it first.

Under B<no> circumstances should 1..M appear in the middle of your
output or more than once.


=item B<'ok', 'not ok'.  Ok?>

Any output from the testscript to standard error is ignored and
bypassed, thus will be seen by the user. Lines written to standard
output containing C</^(not\s+)?ok\b/> are interpreted as feedback for
runtests().  All other lines are discarded.

C</^not ok/> indicates a failed test.  C</^ok/> is a successful test.


=item B<test numbers>

Perl normally expects the 'ok' or 'not ok' to be followed by a test
number.  It is tolerated if the test numbers after 'ok' are
omitted. In this case Test::Harness maintains temporarily its own
counter until the script supplies test numbers again. So the following
test script

    print <<END;
    1..6
    not ok
    ok
    not ok
    ok
    ok
    END

will generate

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


=item B<$Test::Harness::verbose>

The global variable $Test::Harness::verbose is exportable and can be
used to let runtests() display the standard output of the script
without altering the behavior otherwise.

=item B<$Test::Harness::switches>

The global variable $Test::Harness::switches is exportable and can be
used to set perl command line options used for running the test
script(s). The default value is C<-w>.

=item B<Skipping tests>

If the standard output line contains substring C< # Skip> (with
variations in spacing and case) after C<ok> or C<ok NUMBER>, it is
counted as a skipped test.  If the whole testscript succeeds, the
count of skipped tests is included in the generated output.

C<Test::Harness> reports the text after C< # Skip\S*\s+> as a reason
for skipping.  Similarly, one can include a similar explanation in a
C<1..0> line emitted if the test script is skipped completely:

  1..0 # Skipped: no leverage found

=item B<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 will be displayed by
C<Test::Harness> as the reason why testing is stopped.

=item B<Comments>

Additional comments may be put into the testing output on their own
lines.  Comment lines should begin with a '#', Test::Harness will
ignore them.

  ok 1
  # Life is good, the sun is shining, RAM is cheap.
  not ok 2
  # got 'Bush' expected 'Gore'


=head1 EXPORT

C<&runtests> is exported by Test::Harness per default.

C<$verbose> and C<$switches> are exported upon request.


=head1 DIAGNOSTICS

=over 4

=item C<All tests successful.\nFiles=%d,  Tests=%d, %s>

If all tests are successful some statistics about the performance are
printed.

=item C<FAILED tests %s\n\tFailed %d/%d tests, %.2f%% okay.>

For any single script that has failing subtests statistics like the
above are printed.

=item C<Test returned status %d (wstat %d)>

Scripts that return a non-zero exit status, both C<$? E<gt>E<gt> 8>
and C<$?> are printed in a message similar to the above.

=item C<Failed 1 test, %.2f%% okay. %s>

=item C<Failed %d/%d tests, %.2f%% okay. %s>

If not all tests were successful, the script dies with one of the
above messages.

=item C<FAILED--Further testing stopped%s>

If a single subtest decides that further testing will not make sense,
the script dies with this message.

=back

=head1 ENVIRONMENT

Setting C<HARNESS_IGNORE_EXITCODE> makes harness ignore the exit status
of child processes.

Setting C<HARNESS_NOTTY> to a true value forces it to behave as though
STDOUT were not a console.  You may need to set this if you don't want
harness to output more frequent progress messages using carriage returns.
Some consoles may not handle carriage returns properly (which results
in a somewhat messy output).

Setting C<HARNESS_COMPILE_TEST> to a true value will make harness attempt
to compile the test using C<perlcc> before running it.

If C<HARNESS_FILELEAK_IN_DIR> is set to the name of a directory, harness
will check after each test whether new files appeared in that directory,
and report them as

  LEAKED FILES: scr.tmp 0 my.db

If relative, directory name is with respect to the current directory at
the moment runtests() was called.  Putting absolute path into 
C<HARNESS_FILELEAK_IN_DIR> may give more predicatable results.

The value of C<HARNESS_PERL_SWITCHES> will be prepended to the
switches used to invoke perl on each test.  For example, setting
C<HARNESS_PERL_SWITCHES> to "-W" will run all tests with all
warnings enabled.

If C<HARNESS_COLUMNS> is set, then this value will be used for the
width of the terminal. If it is not set then it will default to
C<COLUMNS>. If this is not set, it will default to 80. Note that users
of Bourne-sh based shells will need to C<export COLUMNS> for this
module to use that variable.

Harness sets C<HARNESS_ACTIVE> before executing the individual tests.
This allows the tests to determine if they are being executed through the
harness or by any other means.

=head1 SEE ALSO

L<Test> for writing test scripts and also L<Benchmark> for the
underlying timing routines.

=head1 AUTHORS

Either Tim Bunce or Andreas Koenig, we don't know. What we know for
sure is, that it was inspired by Larry Wall's TEST script that came
with perl distributions for ages. Numerous anonymous contributors
exist. Current maintainer is Andreas Koenig.

=head1 BUGS

Test::Harness uses $^X to determine the perl binary to run the tests
with. Test scripts running via the shebang (C<#!>) line may not be
portable because $^X is not consistent for shebang scripts across
platforms. This is no problem when Test::Harness is run with an
absolute path to the perl binary or when $^X can be found in the path.

=cut