Verify error raised on non-pure build

This will have to be removed before merging as it causes CI to error.

Author: ConorMacBride

setup.py

@@ -0,0 +1,6 @@
+import os
+
+from setuptools import Extension, setup
+
+setup(ext_modules=[Extension('test_package.simple',
+                             [os.path.join('test_package', 'simple.c')])])

test_package/__init__.py

@@ -0,0 +1,3 @@
+from . import simple
+
+__all__ = ["simple"]

test_package/simple.c

@@ -0,0 +1,13 @@
+#include <Python.h>
+
+static struct PyModuleDef moduledef = {
+    PyModuleDef_HEAD_INIT,
+    "simple",
+    NULL,
+    -1,
+    NULL
+};
+PyMODINIT_FUNC
+PyInit_simple(void) {
+    return PyModule_Create(&moduledef);
+}