gh-94808: Add test coverage for PyObject_HasAttrString (#96627)

* gh-94808: Add test for HasAttrString

* Harmonize to Python C code style guidelines

* Add check to verify no exception thrown

Lib/test/test_class.py

@@ -445,6 +445,20 @@ class ClassTests(unittest.TestCase):
         del testme.cardinal
         self.assertCallStack([('__delattr__', (testme, "cardinal"))])
 
+    def testHasAttrString(self):
+        import sys
+        from test.support import import_helper
+        _testcapi = import_helper.import_module('_testcapi')
+
+        class A:
+            def __init__(self):
+                self.attr = 1
+
+        a = A()
+        self.assertEqual(_testcapi.hasattr_string(a, "attr"), True)
+        self.assertEqual(_testcapi.hasattr_string(a, "noattr"), False)
+        self.assertEqual(sys.exc_info(), (None, None, None))
+
     def testDel(self):
         x = []
 

Modules/_testcapimodule.c

@@ -4846,6 +4846,31 @@ sequence_setitem(PyObject *self, PyObject *args)
 }
 
 
+static PyObject *
+hasattr_string(PyObject *self, PyObject* args)
+{
+    PyObject* obj;
+    PyObject* attr_name;
+
+    if (!PyArg_UnpackTuple(args, "hasattr_string", 2, 2, &obj, &attr_name)) {
+        return NULL;
+    }
+
+    if (!PyUnicode_Check(attr_name)) {
+        PyErr_SetString(PyExc_TypeError, "attribute name must a be string");
+        return PyErr_Occurred();
+    }
+
+    const char *name_str = PyUnicode_AsUTF8(attr_name);
+    if (PyObject_HasAttrString(obj, name_str)) {
+        Py_RETURN_TRUE;
+    }
+    else {
+        Py_RETURN_FALSE;
+    }
+}
+
+
 /* Functions for testing C calling conventions (METH_*) are named meth_*,
  * e.g. "meth_varargs" for METH_VARARGS.
  *
@@ -5707,6 +5732,7 @@ static PyMethodDef TestMethods[] = {
     {"write_unraisable_exc", test_write_unraisable_exc, METH_VARARGS},
     {"sequence_getitem", sequence_getitem, METH_VARARGS},
     {"sequence_setitem", sequence_setitem, METH_VARARGS},
+    {"hasattr_string", hasattr_string, METH_VARARGS},
     {"meth_varargs", meth_varargs, METH_VARARGS},
     {"meth_varargs_keywords", _PyCFunction_CAST(meth_varargs_keywords), METH_VARARGS|METH_KEYWORDS},
     {"meth_o", meth_o, METH_O},