use v6-alpha;
use Test;

# L<S29/"Array"/"=item unshift">

=kwid

Unshift tests

=cut

plan 53;

# basic unshift tests

{
    my @unshift = ();

    is(+@unshift, 0, 'we have an empty array');

    unshift(@unshift, 1);
    is(+@unshift, 1, 'we have 1 element in the array');
    is(@unshift[0], 1, 'we found the right element');

    unshift(@unshift, 2);
    is(+@unshift, 2, 'we have 2 elements in the array');
    is(@unshift[0], 2, 'we found the right element');
    is(@unshift[1], 1, 'we found the right element');

    unshift(@unshift, 3);
    is(+@unshift, 3, 'we have 3 element in the array');
    is(@unshift[0], 3, 'we found the right element');
    is(@unshift[1], 2, 'we found the right element');
    is(@unshift[2], 1, 'we found the right element');

    unshift(@unshift, 4);
    is(+@unshift, 4, 'we have 4 element in the array');
    is(@unshift[0], 4, 'we found the right element');
    is(@unshift[1], 3, 'we found the right element');
    is(@unshift[2], 2, 'we found the right element');
    is(@unshift[3], 1, 'we found the right element');
}

# try other variations on calling unshift()

{
    my @unshift = ();

    my $val = 100;

    unshift @unshift, $val;
    is(+@unshift, 1, 'we have 1 element in the array');
    is(@unshift[0], $val, 'unshift @array, $val worked');

    @unshift.unshift(200);
    is(+@unshift, 2, 'we have 2 elements in the array');
    is(@unshift[0], 200, '@unshift.unshift(200) works');
    is(@unshift[1], $val, 'unshift @array, $val worked');

    @unshift.unshift(400);
    is(+@unshift, 3, 'we have 3 elements in the array');
    is(@unshift[0], 400, '@unshift.unshift(400) works');
    is(@unshift[1], 200, '@unshift.unshift(200) works');
    is(@unshift[2], $val, 'unshift @array, $val worked');
}

# try unshifting more than one element

{
    my @unshift = ();

    unshift @unshift, (1, 2, 3);
    is(+@unshift, 3, 'we have 3 elements in the array');
    is(@unshift[0], 1, 'got the expected element');
    is(@unshift[1], 2, 'got the expected element');
    is(@unshift[2], 3, 'got the expected element');

    my @val2 = (4, 5);
    unshift @unshift, @val2;  
    is(+@unshift, 5, 'we have 5 elements in the array');
    is(@unshift[0], 4, 'got the expected element');
    is(@unshift[1], 5, 'got the expected element');
    is(@unshift[2], 1, 'got the expected element');
    is(@unshift[3], 2, 'got the expected element');
    is(@unshift[4], 3, 'got the expected element');
    
    unshift @unshift, 6, 7, 8;  
    is(+@unshift, 8, 'we have 8 elements in the array');
    is(@unshift[0], 6, 'got the expected element');
    is(@unshift[1], 7, 'got the expected element');
    is(@unshift[2], 8, 'got the expected element');
    is(@unshift[3], 4, 'got the expected element');
    is(@unshift[4], 5, 'got the expected element');
    is(@unshift[5], 1, 'got the expected element');
    is(@unshift[6], 2, 'got the expected element');
    is(@unshift[7], 3, 'got the expected element');    
}

# now for the unshift() on an uninitialized array issue

{
    my @unshift;

    unshift @unshift, 42;
    is(+@unshift, 1, 'we have 1 element in the array');
    is(@unshift[0], 42, 'got the element expected');

    unshift @unshift, 2000;
    is(+@unshift, 2, 'we have 1 element in the array');
    is(@unshift[0], 2000, 'got the element expected');
    is(@unshift[1], 42, 'got the element expected');
}

# testing some edge cases
{
    my @unshift = 0 .. 5;
    is(+@unshift, 6, 'starting length is 6');
    
    unshift(@unshift);
    is(+@unshift, 6, 'length is still 6');
    
    @unshift.push();
    is(+@unshift, 6, 'length is still 6');
}

# testing some error cases
{
    dies_ok({ unshift()     }, 'unshift() requires arguments');        
    dies_ok({ 42.unshift(3) }, '.unshift should not work on scalars');
}

# Push with Inf arrays (waiting on answers to perl6-compiler email)
#{
#    my @unshift = 1 .. Inf;
#    # best not to uncomment this it just go on forever
#    todo_throws_ok { 'unshift @unshift, 10' }, '?? what should this error message be ??', 'cannot unshift onto a Inf array';
#}