use Test::More tests => 21;

# Test that Q.pm actually compiles.
BEGIN { use_ok 'Q' };

# Test that the API as documented still exists.
my $q = new_ok Q => [5];
can_ok $q => 'nq';
can_ok $q => 'dq';
can_ok $q => 'n';

# Thread to add some numbers to the queue.
my $enqueue = threads->create(sub {
	$q->nq($_) for 90..99;
});

# Vulnerable to race conditions :-(
sleep 1;
ok !$enqueue->is_joinable, '$q->nq is waiting';

# This breaks encapsulation by peeking at the internals of $q.
# But we want to figure out if $q is waiting at '95'.
ok !(grep { $_==95 } @$q), '95 is not on $q yet';

# Numbers come out of the thread in the correct order:
is $q->dq, $_, "got $_ from queue" for 90..99;

# Queue should now be empty, so not waiting for anything.
sleep 1;
ok $enqueue->is_joinable, '$q->nq is no longer waiting';
$enqueue->join;

# Test that "dq" blocks too.
my $dequeue = threads->create(sub {
	# Add up the numbers we get from the queue.
	my $sum;
	$sum += $q->dq for 1..10;
	return $sum;
});

# We've not added any numbers to the queue yet, so the queue
# should be waiting.
sleep 1;
ok !$dequeue->is_joinable, '$q->dq is waiting';

# Push some numbers into the queue. These sum to 55.
$q->nq($_) for 1..10;

# Queue should have recieved all the numbers.
sleep 1;
ok $dequeue->is_joinable, '$q->dq is no longer waiting';
my $sum = $dequeue->join;

is $sum, 55, 'result of calculation performed in $dequeue is correct';