Merge pull request #657 from Raku/more-hash-tests

More tests for NQP hash behaviour.

t/nqp/108-vmhash.t

@@ -1,4 +1,7 @@
-plan(10);
+plan(28);
+
+my $backend := nqp::getcomp('nqp').backend.name;
+
 class NQPHashClass is repr('VMHash') {
 }
 
@@ -14,7 +17,7 @@ my $clone := nqp::clone($hash);
 $clone<b> := 3;
 is($hash<b>, 2, "changing clone doesn't modify orignal");
 is($clone<a>, 1, 'clone has value taken from orginal');
-is($clone<b>, 3, "clone has a value of it's own");
+is($clone<b>, 3, 'clone has a value of its own');
 
 is(nqp::elems($hash), 2, 'nqp::elems on hash');
 is(0+$hash, 2, 'numifing a hash');
@@ -29,4 +32,71 @@ for $hash -> $kv {
     nqp::push(@kv, $kv);
 }
 
-ok(@kv[0].key eq 'b' && @kv[0].value == 2, 'got correct kv when iterating');
+is(@kv[0].key, 'b', 'got correct kv key when iterating');
+is(@kv[0].value, 2, 'got correct kv value when iterating');
+is(nqp::elems(@kv), 1, 'just one kv when iteratring');
+
+my $iter := nqp::iterator($clone);
+
+my $msg;
+try {
+    my $key := nqp::iterkey_s($iter);
+    CATCH {
+        $msg := nqp::getmessage($_);
+    }
+}
+
+todo('Exceptions for iterators before start NYI on ' ~ $backend, 2)
+    unless $backend eq 'moar';
+ok($msg ne "", 'iterator throws before start');
+is(nqp::index($msg, 'You have not advanced to the first item of the hash iterator'), 0, 'iterator throws correct execption before start');
+
+while ($iter) {
+    nqp::shift($iter);
+    my $key := nqp::iterkey_s($iter);
+    ok(nqp::existskey($clone, $key), 'key from iterator exists');
+    is(nqp::iterval($iter), $clone{$key}, 'value from iterator is consistent');
+    # Can we delete the entries at the iterator?
+    nqp::deletekey($clone, $key);
+    ok(!nqp::existskey($clone, $key), 'key from iterator no longer exists');
+};
+is(nqp::elems($clone), 0, 'empty hash');
+
+$msg := "";
+try {
+    nqp::shift($iter);
+    CATCH {
+      $msg := nqp::getmessage($_);
+    }
+}
+
+todo('Exceptions for iterators NYI on js', 2)
+    if $backend eq 'js';
+ok($msg ne "", 'iterator throws after end');
+# As per comments on https://github.com/Raku/nqp/pull/657
+# the JVM backend should be changed to throw the same error text
+todo('Error message not yet consistent on the JVM', 1)
+    if $backend eq 'jvm';
+is($msg, 'Iteration past end of iterator', 'iterator throws correct exception after end');
+
+$hash<a> := 1;
+is(nqp::elems($hash), 2, 'hash has 2 elements once more');
+
+$iter := nqp::iterator($hash);
+
+nqp::shift($iter);
+my $key := nqp::iterkey_s($iter);
+ok(nqp::existskey($hash, $key), 'first key from iterator exists');
+nqp::deletekey($hash, $key);
+ok(!nqp::existskey($hash, $key), 'first key from iterator no longer exists');
+# This test with the loop unrolled calls nqp::shift immediately after deleting
+# the key at the iterator position, *without* an intervening call to the $iter
+# in boolean context. It takes a different path through the MoarVM ops, meaning
+# that shift in MVMIter.c is called with the iterator in the "just deleted"
+# state. The loop above calls MVM_iter_istrue_hash first, and instead that gets
+# to handle the iterator in the "just deleted" state.
+nqp::shift($iter);
+$key := nqp::iterkey_s($iter);
+ok(nqp::existskey($hash, $key), 'second key from iterator exists');
+nqp::deletekey($hash, $key);
+ok(!nqp::existskey($hash, $key), 'second key from iterator no longer exists');