Make protobuf dependency optional. Part II

PiperOrigin-RevId: 865503087

Author: dmitriplotnikov

py_cel_test.py

@@ -812,15 +812,16 @@ def setUp(self):
     self.msg = test_all_types_pb.TestAllTypes()
     self.msg.single_string = "Hey"
 
-    # "Unimport" descriptor_pool if it is already imported.
-    if "google.protobuf.descriptor_pool" in sys.modules:
-      del sys.modules["google.protobuf.descriptor_pool"]
+    # "Unimport" any google.protobuf modules if they are already imported.
+    for module_name in list(sys.modules):
+      if module_name.startswith("google.protobuf"):
+        del sys.modules[module_name]
 
     # Make it impossible to import descriptor_pool.
     class UnluckyFinder(importlib.abc.MetaPathFinder):
 
       def find_spec(self, fullname, unused_path, unused_target=None):
-        if fullname == "google.protobuf.descriptor_pool":
+        if fullname.startswith("google.protobuf."):
           raise ImportError("Not found")
         return None
 

py_message_factory.cc

@@ -26,6 +26,10 @@ namespace cel_python {
 
 PyMessageFactory::PyMessageFactory(PyObject* descriptor_pool) {
   py_descriptor_pool_ = descriptor_pool;
+  if (py_descriptor_pool_ == nullptr) {
+    return;
+  }
+
   Py_XINCREF(py_descriptor_pool_);
   PyObject* pName =
       PyUnicode_DecodeFSDefault("google.protobuf.message_factory");
@@ -44,6 +48,10 @@ PyMessageFactory::PyMessageFactory(PyObject* descriptor_pool) {
 }
 
 PyMessageFactory::~PyMessageFactory() {
+  if (py_descriptor_pool_ == nullptr) {
+    return;
+  }
+
   auto gil_state = PyGILState_Ensure();
   Py_XDECREF(py_descriptor_pool_);
   Py_XDECREF(py_func_GetMessageClass_);
@@ -91,6 +99,10 @@ PyObject* PyMessageFactory::GetMessageClass(const std::string& message_type) {
 
 PyObject* PyMessageFactory::FromString(const std::string& message_type,
                                        const std::string& serialized_proto) {
+  if (py_descriptor_pool_ == nullptr) {
+    return nullptr;
+  }
+
   ABSL_CHECK(PyGILState_Check());
   PyObject* message_class = GetMessageClass(message_type);
   if (!message_class) {