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#!./perl -w
BEGIN {
chdir 't' if -d 't';
require './test.pl';
set_up_inc('../lib');
}
plan tests => 24;
# not() tests
pass("logical negation of empty list") if not();
is(not(), 1, "logical negation of empty list in numeric comparison");
is(not(), not(0),
"logical negation of empty list compared with logical negation of false value");
# test not(..) and !
note("parens needed around second argument in next two tests\nto preserve list context inside function call");
is(! 1, (not 1),
"high- and low-precedence logical negation of true value");
is(! 0, (not 0),
"high- and low-precedence logical negation of false value");
is(! (0, 0), not(0, 0),
"high- and low-precedence logical negation of lists");
# test the return of !
{
my $not0 = ! 0;
my $not1 = ! 1;
no warnings;
ok($not1 == undef,
"logical negation (high-precedence) of true value is numerically equal to undefined value");
ok($not1 == (),
"logical negation (high-precedence) of true value is numerically equal to empty list");
use warnings;
ok($not1 eq '',
"logical negation (high-precedence) of true value in string context is equal to empty string");
ok($not1 == 0,
"logical negation (high-precedence) of true value is false in numeric context");
ok($not0 == 1,
"logical negation (high-precedence) of false value is true in numeric context");
}
# test the return of not
{
my $not0 = not 0;
my $not1 = not 1;
no warnings;
ok($not1 == undef,
"logical negation (low-precedence) of true value is numerically equal to undefined value");
ok($not1 == (),
"logical negation (low-precedence) of true value is numerically equal to empty list");
use warnings;
ok($not1 eq '',
"logical negation (low-precedence) of true value in string context is equal to empty string");
ok($not1 == 0,
"logical negation (low-precedence) of true value is false in numeric context");
ok($not0 == 1,
"logical negation (low-precedence) of false value is true in numeric context");
}
# test truth of dualvars
SKIP:
{
my $got_dualvar;
eval 'use Scalar::Util "dualvar"; $got_dualvar++';
skip "No Scalar::Util::dualvar", 3 unless $got_dualvar;
my $a = Scalar::Util::dualvar(3, "");
is not($a), 1, 'not(dualvar) ignores int when string is false';
my $b = Scalar::Util::dualvar(3.3,"");
is not($b), 1, 'not(dualvar) ignores float when string is false';
my $c = Scalar::Util::dualvar(0,"1");
is not($c), "", 'not(dualvar) ignores false int when string is true';
}
# test truth of regexps
is not(${qr//}), "", 'dereferenced regexps are true';
# not’s return value should be read-only, as it is the same global scalar
# each time (and test that it is, too).
*yes = \not 0;
*no = \not 1;
for (!0) { eval { $_ = 43 } }
like $@, qr/^Modification of a read-only value attempted at /,
'not 0 is read-only';
for (!1) { eval { $_ = 43 } }
like $@, qr/^Modification of a read-only value attempted at /,
'not 1 is read-only';
require Config;
is \!0, \$yes, '!0 returns the same value each time [perl #114838]';
is \!1, \$no, '!1 returns the same value each time [perl #114838]';
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