Add tests for pairup. (#174)

* Add test for pairup keys and values.

* Add test for pairup list size.

* Use clearer test descriptions.

* Test for exceptions.

S32-basics/pairup.t

@@ -2,10 +2,17 @@ use v6;
 
 use Test;
 
-plan 1;
+plan 5;
 
 {
-    is-deeply Any.pairup(), (), 'pairup on an undefined invocant returns an empty list'
+    is-deeply Any.pairup(), (), 'pairup on an undefined invocant returns an empty list';
+    my @nums = 1..6;
+    my %h = @nums.pairup;
+    is(@nums.pairup.elems, 3, 'pairup returns correct list size');
+    is-deeply(%h.keys.sort, ('1', '3', '5'), 'hash constructed from pairup has correct keys');
+    is-deeply(%h.values.sort, (2, 4, 6), 'hash constructed from pairup has correct values');
+    @nums.push(7);
+    dies-ok(sub{@nums.pairup}, 'pairup on odd numbered list size throws exception');
 }
 
 # vim: ft=perl6