NFC Add test for pyo3 catching rust panics (#3905)

This adds a test PyO3 module which intentionally panics and checks that it
gets properly caught and converted to a Python exception. I think this test
is failing on the wasm-exceptions branch, but in any case it is good to have
explicit test coverage for this.

packages/rust-panic-test/meta.yaml

@@ -0,0 +1,9 @@
+package:
+  name: rust-panic-test
+  version: "1.0"
+source:
+  path: src
+build:
+  script: |
+    rustup toolchain install ${RUST_TOOLCHAIN} && rustup default ${RUST_TOOLCHAIN}
+    rustup target add wasm32-unknown-emscripten --toolchain ${RUST_TOOLCHAIN}

packages/rust-panic-test/src/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "hello-world"
+version = "0.1.0"

packages/rust-panic-test/src/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "rust-panic-test"
+version = "0.1.0"
+edition = "2018"
+publish = false
+
+[dependencies]
+pyo3 = { version = "0.15.2" }
+
+[features]
+extension-module = ["pyo3/extension-module"]
+default = ["extension-module"]
+
+[lib]
+crate-type = ["cdylib"]
+
+[profile.release]
+lto = "thin"
+overflow-checks = true

packages/rust-panic-test/src/pyproject.toml

@@ -0,0 +1,3 @@
+[build-system]
+requires = ["setuptools", "wheel", "setuptools-rust"]
+build-backend = "setuptools.build_meta"

packages/rust-panic-test/src/setup.py

@@ -0,0 +1,12 @@
+from setuptools import setup
+from setuptools_rust import Binding, RustExtension
+
+setup(
+    name="rust_panic_test",
+    version="1.0",
+    rust_extensions=[
+        RustExtension("rust_panic_test", "Cargo.toml", binding=Binding.PyO3)
+    ],
+    # rust extensions are not zip safe, just like C-extensions.
+    zip_safe=False,
+)

packages/rust-panic-test/src/src/lib.rs

@@ -0,0 +1,18 @@
+
+
+#[pyo3::prelude::pyfunction]
+fn panic_test(data: &[u8]) -> bool {
+    if data[0] < 6 {
+        panic!("this is a {} {message:?}", "fancy", message = data);
+    }
+    data[0] < 20
+}
+
+
+
+#[pyo3::prelude::pymodule]
+fn rust_panic_test(py: pyo3::Python<'_>, m: &pyo3::types::PyModule) -> pyo3::PyResult<()> {
+    m.add_function(pyo3::wrap_pyfunction!(panic_test, m)?)?;
+    m.add("PanicException", py.get_type::<pyo3::panic::PanicException>())?;
+    Ok(())
+}

packages/rust-panic-test/test_rust_panic.py

@@ -0,0 +1,12 @@
+from pytest_pyodide import run_in_pyodide
+
+
+@run_in_pyodide(packages=["rust-panic-test"])
+def test_rust_panic(selenium):
+    from pytest import raises
+    from rust_panic_test import PanicException, panic_test
+
+    assert not panic_test(bytes([20]))
+    assert panic_test(bytes([10]))
+    with raises(PanicException):
+        panic_test(bytes([1]))