Add more tests for nqp::index

Author: samcv

t/nqp/107-index.t

@@ -0,0 +1,14 @@
+# string indexing tests.
+my int $x := 100;
+plan(26 * $x);
+# XXX TODO rework this stuff into indexic.t
+# If changing this file, also add equivalent changes to moar/xx-indexic.t
+my str $abc-string := 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
+my int $i := 0;
+my str $abc-x-string := nqp::x($abc-string, $x);
+while ($i < nqp::chars($abc-x-string)) {
+    my int $j := $i % nqp::chars($abc-string);
+    my str $letter := nqp::chr($j + nqp::ord('A'));
+    is( nqp::index($abc-x-string, $letter, 0), $j, "nqp::index('$abc-string' x $x, '$letter', $j)");
+    $i++;
+}