Change shitfn/popn() and shiftn/popn(negative) to be errors.

For #149

lib/perl5i/2/ARRAY.pm

@@ -56,15 +56,27 @@ method grep($filter) {
 }
 
 method popn($times) {
-    $times = 0 unless ($times && $times > 0);
+    Carp::croak("popn() takes a single argument, the number of elements to pop")
+      unless defined $times;
+    Carp::croak("popn() does not take negative arguments")
+      if $times < 0;
+
+    # splice() will choke if you walk off the array, so rein it in
     $times = scalar(@$self) if ($times > scalar(@$self));
+
     my @result = splice(@$self, -$times, $times);
     return wantarray ? @result : \@result;
 }
 
 method shiftn($times) {
-    $times = 0 unless ($times && $times > 0);
+    Carp::croak("shiftn() takes a single argument, the number of elements to pop")
+      unless defined $times;
+    Carp::croak("shiftn() does not take negative arguments")
+      if $times < 0;
+
+    # splice() will choke if you walk off the array, so rein it in
     $times = scalar(@$self) if ($times > scalar(@$self));
+
     my @result = splice(@$self, 0, $times);
     return wantarray ? @result : \@result;
 }

t/popn.t

@@ -1,28 +1,20 @@
 #!/usr/bin/perl
 
+use lib 't/lib';
 use perl5i::latest;
+use Test::perl5i;
 use Test::More;
 
 note "popn with no args"; {
     my @array = (1, 2, 3);
-    my @newarray = @array->popn();
-
-    my @want = (1, 2, 3);
-    my @newwant = ();
-
-    is_deeply \@array, \@want;
-    is_deeply \@newarray, \@newwant;
+    throws_ok { @array->popn(); }
+      qr{^\Qpopn() takes a single argument, the number of elements to pop};
 }
 
-note "popn with arg < 0"; {
+note "popn with negative arg"; {
     my @array = (1, 2, 3);
-    my @newarray = @array->popn(-20);
-
-    my @want = (1, 2, 3);
-    my @newwant = ();
-
-    is_deeply \@array, \@want;
-    is_deeply \@newarray, \@newwant;
+    throws_ok { @array->popn(-20); }
+      qr{^\Qpopn() does not take negative arguments at $0 line};
 }   
 
 note "popn with arg == 0"; {

t/shiftn.t

@@ -1,29 +1,22 @@
 #!/usr/bin/perl
 
+use lib 't/lib';
+use Test::perl5i;
 use perl5i::2;
 use Test::More;
 
 note "shiftn with no args"; {
-    my @array = (1, 2, 3, 4);
-    my @newarray = @array->shiftn();
-
-    my @want = (1, 2, 3, 4);
-    my @newwant = ();
-
-    is_deeply \@array, \@want;
-    is_deeply \@newarray, \@newwant;
+    my @array = (1, 2, 3);
+    throws_ok { @array->shiftn(); }
+      qr{^\Qshiftn() takes a single argument, the number of elements to pop};
 }
 
-note "shiftn with arg < 0"; {
-    my @array = (1, 2, 3, 4, 5);
-    my @newarray = @array->shiftn(-20);
-
-    my @want = (1, 2, 3, 4, 5);
-    my @newwant = ();
-
-    is_deeply \@array, \@want;
-    is_deeply \@newarray, \@newwant;
-}
+note "shiftn with negative arg"; {
+    my @array = (1, 2, 3);
+    throws_ok { @array->shiftn(-20); }
+      qr{^\Qshiftn() does not take negative arguments at $0 line};
+}   
+
 
 note "shiftn with arg == 0"; {
     my @array = (1, 2, 3);