TST: use C instead of Cython for editable support tests

Cython does not support yet free-threading Python.

Author: dnicolodi

tests/packages/complex/extension.c

@@ -0,0 +1,26 @@
+// SPDX-FileCopyrightText: 2024 The meson-python developers
+//
+// SPDX-License-Identifier: MIT
+
+#include <Python.h>
+
+static PyObject* answer(PyObject* self) {
+    return PyLong_FromLong(42);
+}
+
+static PyMethodDef methods[] = {
+    {"answer", (PyCFunction) answer, METH_NOARGS, NULL},
+    {NULL, NULL, 0, NULL},
+};
+
+static struct PyModuleDef module = {
+    PyModuleDef_HEAD_INIT,
+    "extension",
+    NULL,
+    -1,
+    methods,
+};
+
+PyMODINIT_FUNC PyInit_extension(void) {
+    return PyModule_Create(&module);
+}

tests/packages/complex/meson.build

@@ -33,6 +33,13 @@ install_subdir(
     exclude_files: ['more/meson.build', 'more/baz.pyx'],
 )
 
+py.extension_module(
+    'extension',
+    'extension.c',
+    install: true,
+    subdir: 'complex',
+)
+
 py.extension_module(
     'test',
     'test.pyx',

tests/test_editable.py

@@ -104,9 +104,9 @@ def test_mesonpy_meta_finder(package_complex, tmp_path):
         import complex
         assert complex.__spec__.origin == os.fspath(package_complex / 'complex/__init__.py')
         assert complex.__file__ == os.fspath(package_complex / 'complex/__init__.py')
-        import complex.test
-        assert complex.test.__spec__.origin == os.fspath(tmp_path / f'test{EXT_SUFFIX}')
-        assert complex.test.answer() == 42
+        import complex.extension
+        assert complex.extension.__spec__.origin == os.fspath(tmp_path / f'extension{EXT_SUFFIX}')
+        assert complex.extension.answer() == 42
         import complex.namespace.foo
         assert complex.namespace.foo.__spec__.origin == os.fspath(package_complex / 'complex/namespace/foo.py')
         assert complex.namespace.foo.foo() == 'foo'
@@ -223,6 +223,7 @@ def test_editable_pkgutils_walk_packages(package_complex, tmp_path):
         packages = {m.name for m in pkgutil.walk_packages(complex.__path__, complex.__name__ + '.')}
         assert packages == {
             'complex.bar',
+            'complex.extension',
             'complex.more',
             'complex.more.baz',
             'complex.more.move',