Add a very simple test for Parser::to_linecol.

This test shows that in some cases converting error offsets generated by
the parser to line and column numbers will panic ('arithmetic operation
overflowed') in debug mode, and return an incorrect column number in
release mode.

1 files changed, 6 insertions, 0 deletions

diff --git a/tests/invalid.rs b/tests/invalid.rs
index 3df4d02..e9a94e9 100644
--- a/tests/invalid.rs
+++ b/tests/invalid.rs
@@ -7,6 +7,12 @@ fn run(toml: &str) {
     let table = p.parse();
     assert!(table.is_none());
     assert!(p.errors.len() > 0);
+
+    // test Parser::to_linecol with the generated error offsets
+    for error in &p.errors {
+      p.to_linecol(error.lo);
+      p.to_linecol(error.hi);
+    }
 }
 
 macro_rules! test( ($name:ident, $toml:expr) => (