1 files changed, 41 insertions, 0 deletions
diff --git a/t/magic.t b/t/magic.t
new file mode 100644
index 0000000..366f275
--- /dev/null
+++ b/t/magic.t
@@ -0,0 +1,41 @@
+# Check that the magic signature at the top of struct p_state works and that we
+# catch modifications to _hparser_xs_state gracefully
+
+use Test::More tests => 5;
+
+use HTML::Parser;
+
+$p = HTML::Parser->new(api_version => 3);
+
+$p->xml_mode(1);
+
+# We should not be able to simply modify this stuff
+eval {
+    ${$p->{_hparser_xs_state}} += 4;
+};
+like($@, qr/^Modification of a read-only value attempted/);
+
+
+my $x = delete $p->{_hparser_xs_state};
+
+eval {
+    $p->xml_mode(1);
+};
+like($@, qr/^Can't find '_hparser_xs_state'/);
+
+$p->{_hparser_xs_state} = \($$x + 16);
+
+eval {
+    $p->xml_mode(1);
+};
+like($@, $] >= 5.008 ? qr/^Lost parser state magic/ : qr/^Bad signature in parser state object/);
+
+$p->{_hparser_xs_state} = 33;
+eval {
+    $p->xml_mode(1);
+};
+like($@,  qr/^_hparser_xs_state element is not a reference/);
+
+$p->{_hparser_xs_state} = $x;
+
+ok($p->xml_mode(0));