gh-84436: Add integration C API tests for immortal objects (gh-103962)

4 files changed, 52 insertions, 1 deletions

diff --git a/Modules/Setup.stdlib.in b/Modules/Setup.stdlib.in
index fe1b9f8..a90c1e9 100644
--- a/Modules/Setup.stdlib.in
+++ b/Modules/Setup.stdlib.in
@@ -169,7 +169,7 @@
 @MODULE__XXTESTFUZZ_TRUE@_xxtestfuzz _xxtestfuzz/_xxtestfuzz.c _xxtestfuzz/fuzzer.c
 @MODULE__TESTBUFFER_TRUE@_testbuffer _testbuffer.c
 @MODULE__TESTINTERNALCAPI_TRUE@_testinternalcapi _testinternalcapi.c
-@MODULE__TESTCAPI_TRUE@_testcapi _testcapimodule.c _testcapi/vectorcall.c _testcapi/vectorcall_limited.c _testcapi/heaptype.c _testcapi/unicode.c _testcapi/getargs.c _testcapi/pytime.c _testcapi/datetime.c _testcapi/docstring.c _testcapi/mem.c _testcapi/watchers.c _testcapi/long.c _testcapi/float.c _testcapi/structmember.c _testcapi/exceptions.c _testcapi/code.c _testcapi/pyos.c
+@MODULE__TESTCAPI_TRUE@_testcapi _testcapimodule.c _testcapi/vectorcall.c _testcapi/vectorcall_limited.c _testcapi/heaptype.c _testcapi/unicode.c _testcapi/getargs.c _testcapi/pytime.c _testcapi/datetime.c _testcapi/docstring.c _testcapi/mem.c _testcapi/watchers.c _testcapi/long.c _testcapi/float.c _testcapi/structmember.c _testcapi/exceptions.c _testcapi/code.c _testcapi/pyos.c _testcapi/immortal.c
 @MODULE__TESTCLINIC_TRUE@_testclinic _testclinic.c
 
 # Some testing modules MUST be built as shared libraries.
diff --git a/Modules/_testcapi/immortal.c b/Modules/_testcapi/immortal.c
new file mode 100644
index 0000000..10e1733
--- /dev/null
+++ b/Modules/_testcapi/immortal.c
@@ -0,0 +1,47 @@
+#include "parts.h"
+
+int verify_immortality(PyObject *object) 
+{
+    assert(_Py_IsImmortal(object));
+    Py_ssize_t old_count = Py_REFCNT(object);
+    for (int j = 0; j < 10000; j++) {
+        Py_DECREF(object);
+    }
+    Py_ssize_t current_count = Py_REFCNT(object);
+    return old_count == current_count;
+}
+
+static PyObject *
+test_immortal_builtins(PyObject *self, PyObject *Py_UNUSED(ignored))
+{
+    PyObject *objects[] = {Py_True, Py_False, Py_None, Py_Ellipsis};
+    Py_ssize_t n = Py_ARRAY_LENGTH(objects);
+    for (Py_ssize_t i = 0; i < n; i++) {
+        assert(verify_immortality(objects[i]));
+    }
+    Py_RETURN_NONE;
+}
+
+static PyObject *
+test_immortal_small_ints(PyObject *self, PyObject *Py_UNUSED(ignored))
+{
+    for (int i = -5; i <= 256; i++) {
+        assert(verify_immortality(PyLong_FromLong(i)));
+    }
+    Py_RETURN_NONE;
+}
+
+static PyMethodDef test_methods[] = {
+    {"test_immortal_builtins",   test_immortal_builtins,     METH_NOARGS},
+    {"test_immortal_small_ints", test_immortal_small_ints,   METH_NOARGS},
+    {NULL},
+};
+
+int
+_PyTestCapi_Init_Immortal(PyObject *mod)
+{
+    if (PyModule_AddFunctions(mod, test_methods) < 0) {
+        return -1;
+    }
+    return 0;
+}
diff --git a/Modules/_testcapi/parts.h b/Modules/_testcapi/parts.h
index 60ec81d..4d2d683 100644
--- a/Modules/_testcapi/parts.h
+++ b/Modules/_testcapi/parts.h
@@ -39,6 +39,7 @@ int _PyTestCapi_Init_Structmember(PyObject *module);
 int _PyTestCapi_Init_Exceptions(PyObject *module);
 int _PyTestCapi_Init_Code(PyObject *module);
 int _PyTestCapi_Init_PyOS(PyObject *module);
+int _PyTestCapi_Init_Immortal(PyObject *module);
 
 #ifdef LIMITED_API_AVAILABLE
 int _PyTestCapi_Init_VectorcallLimited(PyObject *module);
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index a5d23b1..30b8b6c 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -4313,6 +4313,9 @@ PyInit__testcapi(void)
     if (_PyTestCapi_Init_PyOS(m) < 0) {
         return NULL;
     }
+    if (_PyTestCapi_Init_Immortal(m) < 0) {
+        return NULL;
+    }
 
 #ifndef LIMITED_API_AVAILABLE
     PyModule_AddObjectRef(m, "LIMITED_API_AVAILABLE", Py_False);