From 466def32e5b161129810f3e4a61b0fb08df57526 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stephan=20H=C3=BCgel?= <shugel@tcd.ie>
Date: Mon, 30 Dec 2024 16:07:53 +0000
Subject: [PATCH] Use an assert to ensure error code is always > 0, and add a
 test

---
 src/proj.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/proj.rs b/src/proj.rs
index a24e64b3..3c4ac0fd 100644
--- a/src/proj.rs
+++ b/src/proj.rs
@@ -177,6 +177,9 @@ pub(crate) unsafe fn _string(raw_ptr: *const c_char) -> Result<String, str::Utf8
 
 /// Look up an error message using the error code
 fn error_message(code: c_int) -> Result<String, str::Utf8Error> {
+    // Ensure that if we ever get a 0 error code back from libroj, we throw an error
+    // the minimum error code should be 1024
+    assert_ne!(code, 0);
     unsafe {
         let rv = proj_errno_string(code);
         _string(rv)
@@ -1484,4 +1487,10 @@ mod test {
         assert_eq!(area.north, 84.73);
         assert!(name.contains("Europe"));
     }
+
+    #[test]
+    #[should_panic]
+    fn error_message_zero_code() {
+        assert!(error_message(0).is_err());
+    }
 }