From 96984b2860a98ee470f93c75d96eb1ff37f1f18b Mon Sep 17 00:00:00 2001
From: David Hewitt <1939362+davidhewitt@users.noreply.github.com>
Date: Thu, 12 Nov 2020 08:52:11 +0000
Subject: [PATCH] coverage: simplify mechanism for panic=unwind tests

---
 src/err/mod.rs | 22 +++++++++++-----------
 src/lib.rs     |  6 ++++++
 src/python.rs  |  7 ++-----
 3 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/src/err/mod.rs b/src/err/mod.rs
index 8a1b93987f8..c1a384cfd8e 100644
--- a/src/err/mod.rs
+++ b/src/err/mod.rs
@@ -526,7 +526,6 @@ fn exceptions_must_derive_from_base_exception(py: Python) -> PyErr {
 mod tests {
     use super::PyErrState;
     use crate::exceptions;
-    use crate::panic::PanicException;
     use crate::{PyErr, Python};
 
     #[test]
@@ -540,23 +539,24 @@ mod tests {
     }
 
     #[test]
-    fn fetching_panic_exception_panics() {
-        // If -Cpanic=abort is specified, we can't catch panic.
-        if option_env!("RUSTFLAGS")
-            .map(|s| s.contains("-Cpanic=abort"))
-            .unwrap_or(false)
-        {
-            return;
+    #[should_panic(expected = "new panic")]
+    fn fetching_panic_exception_resumes_unwind() {
+        // TODO replace with #[cfg(panic = "unwind")] once stable
+        if !crate::cfg_panic_unwind() {
+            // panic to meet the expected abort in panic=abort :-/
+            panic!("new panic");
         }
 
+        use crate::panic::PanicException;
+
         let gil = Python::acquire_gil();
         let py = gil.python();
         let err: PyErr = PanicException::new_err("new panic");
         err.restore(py);
         assert!(PyErr::occurred(py));
-        let started_unwind =
-            std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| PyErr::fetch(py))).is_err();
-        assert!(started_unwind);
+
+        // should resume unwind
+        let _ = PyErr::fetch(py);
     }
 
     #[test]
diff --git a/src/lib.rs b/src/lib.rs
index 67544e4f095..9326700c344 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -384,3 +384,9 @@ pub mod doc_test {
     doctest!("../guide/src/types.md", guide_types_md);
     doctest!("../guide/src/trait_bounds.md", guide_trait_bounds_md);
 }
+
+// interim helper until #[cfg(panic = ...)] is stable
+#[cfg(test)]
+fn cfg_panic_unwind() -> bool {
+    option_env!("RUSTFLAGS").map_or(true, |var| !var.contains("-Cpanic=abort"))
+}
diff --git a/src/python.rs b/src/python.rs
index bdd15babe50..f58f2f2b654 100644
--- a/src/python.rs
+++ b/src/python.rs
@@ -588,11 +588,8 @@ mod test {
 
     #[test]
     fn test_allow_threads_panics_safely() {
-        // If -Cpanic=abort is specified, we can't catch panic.
-        if option_env!("RUSTFLAGS")
-            .map(|s| s.contains("-Cpanic=abort"))
-            .unwrap_or(false)
-        {
+        // TODO replace with #[cfg(panic = "unwind")] once stable
+        if !crate::cfg_panic_unwind() {
             return;
         }