diff --git a/python/descriptor.c b/python/descriptor.c
index 3877e55a5b..b7e8854a85 100644
--- a/python/descriptor.c
+++ b/python/descriptor.c
@@ -30,6 +30,7 @@
 #include "python/convert.h"
 #include "python/descriptor_containers.h"
 #include "python/descriptor_pool.h"
+#include "python/message.h"
 #include "python/protobuf.h"
 #include "upb/def.h"
 #include "upb/util/def_to_proto.h"
@@ -144,13 +145,9 @@ static PyObject* PyUpb_DescriptorBase_GetOptions(PyUpb_DescriptorBase* self,
 
 typedef void* PyUpb_ToProto_Func(const void* def, upb_arena* arena);
 
-static PyObject* PyUpb_DescriptorBase_CopyToProto(PyObject* _self,
-                                                  PyUpb_ToProto_Func* func,
-                                                  const upb_msglayout* layout,
-                                                  PyObject* py_proto) {
+static PyObject* PyUpb_DescriptorBase_GetSerializedProto(
+    PyObject* _self, PyUpb_ToProto_Func* func, const upb_msglayout* layout) {
   PyUpb_DescriptorBase* self = (void*)_self;
-  PyObject* ret = NULL;
-  PyObject* str = NULL;
   upb_arena* arena = upb_arena_new();
   if (!arena) PYUPB_RETURN_OOM;
   upb_msg* proto = func(self->def, arena);
@@ -158,20 +155,24 @@ static PyObject* PyUpb_DescriptorBase_CopyToProto(PyObject* _self,
   size_t size;
   char* pb = upb_encode(proto, layout, arena, &size);
   if (!pb) goto oom;
-  str = PyBytes_FromStringAndSize(pb, size);
-  if (!str) goto oom;
-  // Disabled until python/message.c is reviewed and checked in.
-  // PyObject *ret = PyUpb_CMessage_MergeFromString(py_proto, str);
-  PyErr_Format(PyExc_NotImplementedError, "Not yet implemented");
-
-done:
-  Py_XDECREF(str);
+  PyObject* str = PyBytes_FromStringAndSize(pb, size);
   upb_arena_free(arena);
-  return ret;
+  return str;
 
 oom:
+  upb_arena_free(arena);
   PyErr_SetNone(PyExc_MemoryError);
-  goto done;
+  return NULL;
+}
+
+static PyObject* PyUpb_DescriptorBase_CopyToProto(PyObject* _self,
+                                                  PyUpb_ToProto_Func* func,
+                                                  const upb_msglayout* layout,
+                                                  PyObject* py_proto) {
+  PyObject* serialized =
+      PyUpb_DescriptorBase_GetSerializedProto(_self, func, layout);
+  if (!serialized) return NULL;
+  return PyUpb_CMessage_MergeFromString(py_proto, serialized);
 }
 
 static void PyUpb_DescriptorBase_Dealloc(PyUpb_DescriptorBase* base) {
@@ -1065,6 +1066,13 @@ static PyObject* PyUpb_FileDescriptor_GetPackage(PyObject* _self,
   return PyUnicode_FromString(upb_filedef_package(self->def));
 }
 
+static PyObject* PyUpb_FileDescriptor_GetSerializedPb(PyObject* self,
+                                                      void* closure) {
+  return PyUpb_DescriptorBase_GetSerializedProto(
+      self, (PyUpb_ToProto_Func*)&upb_FileDef_ToProto,
+      &google_protobuf_FileDescriptorProto_msginit);
+}
+
 static PyObject* PyUpb_FileDescriptor_GetMessageTypesByName(PyObject* _self,
                                                             void* closure) {
   static PyUpb_ByNameMap_Funcs funcs = {
@@ -1180,6 +1188,7 @@ static PyGetSetDef PyUpb_FileDescriptor_Getters[] = {
     {"pool", PyUpb_FileDescriptor_GetPool, NULL, "pool"},
     {"name", (getter)PyUpb_FileDescriptor_GetName, NULL, "name"},
     {"package", PyUpb_FileDescriptor_GetPackage, NULL, "package"},
+    {"serialized_pb", PyUpb_FileDescriptor_GetSerializedPb},
     {"message_types_by_name", PyUpb_FileDescriptor_GetMessageTypesByName, NULL,
      "Messages by name"},
     {"enum_types_by_name", PyUpb_FileDescriptor_GetEnumTypesByName, NULL,
diff --git a/python/descriptor_pool.c b/python/descriptor_pool.c
index 8e95bdf526..73bd0679ba 100644
--- a/python/descriptor_pool.c
+++ b/python/descriptor_pool.c
@@ -28,6 +28,7 @@
 #include "python/descriptor_pool.h"
 
 #include "python/descriptor.h"
+#include "python/message.h"
 #include "python/protobuf.h"
 #include "upb/def.h"
 
@@ -38,7 +39,7 @@
 typedef struct {
   PyObject_HEAD
   upb_symtab* symtab;
-  PyObject* db;
+  PyObject* db;  // The DescriptorDatabase underlying this pool.  May be NULL.
 } PyUpb_DescriptorPool;
 
 PyObject* PyUpb_DescriptorPool_GetDefaultPool() {
@@ -46,9 +47,8 @@ PyObject* PyUpb_DescriptorPool_GetDefaultPool() {
   return s->default_pool;
 }
 
-static PyObject* PyUpb_DescriptorPool_DoCreateWithCache(PyTypeObject* type,
-                                               PyObject* db,
-                                               PyUpb_WeakMap *obj_cache) {
+static PyObject* PyUpb_DescriptorPool_DoCreateWithCache(
+    PyTypeObject* type, PyObject* db, PyUpb_WeakMap* obj_cache) {
   PyUpb_DescriptorPool* pool = (void*)PyType_GenericAlloc(type, 0);
   pool->symtab = upb_symtab_new();
   pool->db = db;
@@ -85,8 +85,8 @@ PyObject* PyUpb_DescriptorPool_Get(const upb_symtab* symtab) {
 }
 
 static void PyUpb_DescriptorPool_Dealloc(PyUpb_DescriptorPool* self) {
-  upb_symtab_free(self->symtab);
   PyUpb_DescriptorPool_Clear(self);
+  upb_symtab_free(self->symtab);
   PyUpb_ObjCache_Delete(self->symtab);
   PyUpb_Dealloc(self);
 }
@@ -106,6 +106,7 @@ static PyObject* PyUpb_DescriptorPool_New(PyTypeObject* type, PyObject* args,
     return NULL;
   }
 
+  if (db == Py_None) db = NULL;
   return PyUpb_DescriptorPool_DoCreate(type, db);
 }
 
@@ -163,6 +164,40 @@ done:
   return result;
 }
 
+static PyObject* PyUpb_DescriptorPool_Add(PyObject* _self,
+                                          PyObject* file_desc) {
+  PyObject* subargs = PyTuple_New(0);
+  // TODO: check file_desc type more.
+  PyObject* serialized =
+      PyUpb_CMessage_SerializeToString(file_desc, subargs, NULL);
+  Py_DECREF(subargs);
+  if (!serialized) return NULL;
+  PyObject* ret = PyUpb_DescriptorPool_AddSerializedFile(_self, serialized);
+  Py_DECREF(serialized);
+  return ret;
+}
+
+/*
+ * PyUpb_DescriptorPool_FindFileByName()
+ *
+ * Implements:
+ *   DescriptorPool.FindFileByName(self, name)
+ */
+static PyObject* PyUpb_DescriptorPool_FindFileByName(PyObject* _self,
+                                                     PyObject* arg) {
+  PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
+
+  const char* name = PyUpb_GetStrData(arg);
+  if (!name) return NULL;
+
+  const upb_filedef* file = upb_symtab_lookupfile(self->symtab, name);
+  if (file == NULL) {
+    return PyErr_Format(PyExc_KeyError, "Couldn't find file %.200s", name);
+  }
+
+  return PyUpb_FileDescriptor_Get(file);
+}
+
 /*
  * PyUpb_DescriptorPool_FindExtensionByName()
  *
@@ -184,40 +219,214 @@ static PyObject* PyUpb_DescriptorPool_FindExtensionByName(PyObject* _self,
   return PyUpb_FieldDescriptor_Get(field);
 }
 
+/*
+ * PyUpb_DescriptorPool_FindMessageTypeByName()
+ *
+ * Implements:
+ *   DescriptorPool.FindMessageTypeByName(self, name)
+ */
+static PyObject* PyUpb_DescriptorPool_FindMessageTypeByName(PyObject* _self,
+                                                            PyObject* arg) {
+  PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
+
+  const char* name = PyUpb_GetStrData(arg);
+  if (!name) return NULL;
+
+  const upb_msgdef* m = upb_symtab_lookupmsg(self->symtab, name);
+  if (m == NULL) {
+    return PyErr_Format(PyExc_KeyError, "Couldn't find message %.200s", name);
+  }
+
+  return PyUpb_Descriptor_Get(m);
+}
+
+// Splits a dotted symbol like foo.bar.baz on the last dot.  Returns the portion
+// after the last dot (baz) and updates `*parent_size` to the length of the
+// parent (foo.bar).  Returns NULL if no dots were present.
+static const char* PyUpb_DescriptorPool_SplitSymbolName(const char* sym,
+                                                        size_t* parent_size) {
+  const char* last_dot = strrchr(sym, '.');
+  if (!last_dot) return NULL;
+  *parent_size = last_dot - sym;
+  return last_dot + 1;
+}
+
+/*
+ * PyUpb_DescriptorPool_FindFieldByName()
+ *
+ * Implements:
+ *   DescriptorPool.FindFieldByName(self, name)
+ */
+static PyObject* PyUpb_DescriptorPool_FindFieldByName(PyObject* _self,
+                                                      PyObject* arg) {
+  PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
+
+  const char* name = PyUpb_GetStrData(arg);
+  if (!name) return NULL;
+
+  // First lookup as extension.
+  const upb_fielddef* f = upb_symtab_lookupext(self->symtab, name);
+
+  if (!f) {
+    // Otherwise look for a normal field.
+    size_t parent_size;
+    const char* child =
+        PyUpb_DescriptorPool_SplitSymbolName(name, &parent_size);
+    if (child) {
+      const upb_msgdef* parent =
+          upb_symtab_lookupmsg2(self->symtab, name, parent_size);
+      if (parent) {
+        f = upb_msgdef_ntofz(parent, child);
+      }
+    }
+  }
+
+  if (!f) {
+    return PyErr_Format(PyExc_KeyError, "Couldn't find message %.200s", name);
+  }
+
+  return PyUpb_FieldDescriptor_Get(f);
+}
+
+/*
+ * PyUpb_DescriptorPool_FindEnumTypeByName()
+ *
+ * Implements:
+ *   DescriptorPool.FindEnumTypeByName(self, name)
+ */
+static PyObject* PyUpb_DescriptorPool_FindEnumTypeByName(PyObject* _self,
+                                                         PyObject* arg) {
+  PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
+
+  const char* name = PyUpb_GetStrData(arg);
+  if (!name) return NULL;
+
+  const upb_enumdef* e = upb_symtab_lookupenum(self->symtab, name);
+  if (e == NULL) {
+    return PyErr_Format(PyExc_KeyError, "Couldn't find enum %.200s", name);
+  }
+
+  return PyUpb_EnumDescriptor_Get(e);
+}
+
+/*
+ * PyUpb_DescriptorPool_FindOneofByName()
+ *
+ * Implements:
+ *   DescriptorPool.FindOneofByName(self, name)
+ */
+static PyObject* PyUpb_DescriptorPool_FindOneofByName(PyObject* _self,
+                                                      PyObject* arg) {
+  PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
+
+  const char* name = PyUpb_GetStrData(arg);
+  if (!name) return NULL;
+
+  size_t parent_size;
+  const char* child = PyUpb_DescriptorPool_SplitSymbolName(name, &parent_size);
+
+  if (child) {
+    const upb_msgdef* parent =
+        upb_symtab_lookupmsg2(self->symtab, name, parent_size);
+    if (parent) {
+      const upb_oneofdef* o = upb_msgdef_ntooz(parent, child);
+      return PyUpb_OneofDescriptor_Get(o);
+    }
+  }
+
+  return PyErr_Format(PyExc_KeyError, "Couldn't find enum %.200s", name);
+}
+
+static PyObject* PyUpb_DescriptorPool_FindServiceByName(PyObject* _self,
+                                                        PyObject* arg) {
+  PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
+
+  const char* name = PyUpb_GetStrData(arg);
+  if (!name) return NULL;
+
+  const upb_servicedef* s = upb_symtab_lookupservice(self->symtab, name);
+  if (s == NULL) {
+    return PyErr_Format(PyExc_KeyError, "Couldn't find enum %.200s", name);
+  }
+
+  return PyUpb_ServiceDescriptor_Get(s);
+}
+
+static PyObject* PyUpb_DescriptorPool_FindFileContainingSymbol(PyObject* _self,
+                                                               PyObject* arg) {
+  PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
+
+  const char* name = PyUpb_GetStrData(arg);
+  if (!name) return NULL;
+
+  const upb_filedef* f = upb_symtab_lookupfileforsym(self->symtab, name);
+  if (f == NULL) {
+    return PyErr_Format(PyExc_KeyError, "Couldn't find symbol %.200s", name);
+  }
+
+  return PyUpb_FileDescriptor_Get(f);
+}
+
+static PyObject* PyUpb_DescriptorPool_FindExtensionByNumber(PyObject* _self,
+                                                            PyObject* args) {
+  PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
+  PyObject* message_descriptor;
+  int number;
+  if (!PyArg_ParseTuple(args, "Oi", &message_descriptor, &number)) {
+    return NULL;
+  }
+
+  const upb_fielddef* f = upb_symtab_lookupextbynum(
+      self->symtab, PyUpb_Descriptor_GetDef(message_descriptor), number);
+  if (f == NULL) {
+    return PyErr_Format(PyExc_KeyError, "Couldn't find Extension %d", number);
+  }
+
+  return PyUpb_FieldDescriptor_Get(f);
+}
+
+static PyObject* PyUpb_DescriptorPool_FindAllExtensions(PyObject* _self,
+                                                        PyObject* msg_desc) {
+  PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
+  const upb_msgdef* m = PyUpb_Descriptor_GetDef(msg_desc);
+  size_t n;
+  const upb_fielddef** ext = upb_symtab_getallexts(self->symtab, m, &n);
+  PyObject* ret = PyList_New(n);
+  for (size_t i = 0; i < n; i++) {
+    PyObject* field = PyUpb_FieldDescriptor_Get(ext[i]);
+    if (!field) return NULL;
+    PyList_SetItem(ret, i, field);
+  }
+  return ret;
+}
+
 static PyMethodDef PyUpb_DescriptorPool_Methods[] = {
-    /*
-      TODO: implement remaining methods.
-    { "Add", Add, METH_O,
-      "Adds the FileDescriptorProto and its types to this pool." },
-      */
+    {"Add", PyUpb_DescriptorPool_Add, METH_O,
+     "Adds the FileDescriptorProto and its types to this pool."},
     {"AddSerializedFile", PyUpb_DescriptorPool_AddSerializedFile, METH_O,
      "Adds a serialized FileDescriptorProto to this pool."},
-    /*
-    { "FindFileByName", FindFileByName, METH_O,
-      "Searches for a file descriptor by its .proto name." },
-    { "FindMessageTypeByName", FindMessageByName, METH_O,
-      "Searches for a message descriptor by full name." },
-    { "FindFieldByName", FindFieldByNameMethod, METH_O,
-      "Searches for a field descriptor by full name." },
-      */
+    {"FindFileByName", PyUpb_DescriptorPool_FindFileByName, METH_O,
+     "Searches for a file descriptor by its .proto name."},
+    {"FindMessageTypeByName", PyUpb_DescriptorPool_FindMessageTypeByName,
+     METH_O, "Searches for a message descriptor by full name."},
+    {"FindFieldByName", PyUpb_DescriptorPool_FindFieldByName, METH_O,
+     "Searches for a field descriptor by full name."},
     {"FindExtensionByName", PyUpb_DescriptorPool_FindExtensionByName, METH_O,
      "Searches for extension descriptor by full name."},
-    /*
-    { "FindEnumTypeByName", FindEnumTypeByNameMethod, METH_O,
-      "Searches for enum type descriptor by full name." },
-    { "FindOneofByName", FindOneofByNameMethod, METH_O,
-      "Searches for oneof descriptor by full name." },
-    { "FindServiceByName", FindServiceByName, METH_O,
-      "Searches for service descriptor by full name." },
-    { "FindMethodByName", FindMethodByName, METH_O,
-      "Searches for method descriptor by full name." },
-    { "FindFileContainingSymbol", FindFileContainingSymbol, METH_O,
-      "Gets the FileDescriptor containing the specified symbol." },
-    { "FindExtensionByNumber", FindExtensionByNumber, METH_VARARGS,
-      "Gets the extension descriptor for the given number." },
-    { "FindAllExtensions", FindAllExtensions, METH_O,
-      "Gets all known extensions of the given message descriptor." },
-    */
+    {"FindEnumTypeByName", PyUpb_DescriptorPool_FindEnumTypeByName, METH_O,
+     "Searches for enum type descriptor by full name."},
+    {"FindOneofByName", PyUpb_DescriptorPool_FindOneofByName, METH_O,
+     "Searches for oneof descriptor by full name."},
+    {"FindServiceByName", PyUpb_DescriptorPool_FindServiceByName, METH_O,
+     "Searches for service descriptor by full name."},
+    //{ "Find, PyUpb_DescriptorPool_Find, METH_O,
+    //  "Searches for method descriptor by full name." },
+    {"FindFileContainingSymbol", PyUpb_DescriptorPool_FindFileContainingSymbol,
+     METH_O, "Gets the FileDescriptor containing the specified symbol."},
+    {"FindExtensionByNumber", PyUpb_DescriptorPool_FindExtensionByNumber,
+     METH_VARARGS, "Gets the extension descriptor for the given number."},
+    {"FindAllExtensions", PyUpb_DescriptorPool_FindAllExtensions, METH_O,
+     "Gets all known extensions of the given message descriptor."},
     {NULL}};
 
 static PyType_Slot PyUpb_DescriptorPool_Slots[] = {
@@ -241,9 +450,9 @@ static PyType_Spec PyUpb_DescriptorPool_Spec = {
 // -----------------------------------------------------------------------------
 
 bool PyUpb_InitDescriptorPool(PyObject* m) {
-  PyUpb_ModuleState *state = PyUpb_ModuleState_GetFromModule(m);
+  PyUpb_ModuleState* state = PyUpb_ModuleState_GetFromModule(m);
   PyTypeObject* descriptor_pool_type =
-      AddObject(m, "DescriptorPool", &PyUpb_DescriptorPool_Spec);
+      PyUpb_AddClass(m, &PyUpb_DescriptorPool_Spec);
 
   if (!descriptor_pool_type) return false;
 
diff --git a/python/descriptor_pool.h b/python/descriptor_pool.h
index f43764ecc2..0bda5b186e 100644
--- a/python/descriptor_pool.h
+++ b/python/descriptor_pool.h
@@ -32,12 +32,17 @@
 
 #include "protobuf.h"
 
-PyObject* PyUpb_DescriptorPool_GetSerializedPb(PyObject* _self,
-                                               const char* filename);
+// Returns a Python wrapper object for the given symtab. The symtab must have
+// been created from a Python DescriptorPool originally.
 PyObject* PyUpb_DescriptorPool_Get(const upb_symtab* symtab);
+
+// Given a Python DescriptorPool, returns the underlying symtab.
 upb_symtab* PyUpb_DescriptorPool_GetSymtab(PyObject* pool);
+
+// Returns the default DescriptorPool (a global singleton).
 PyObject* PyUpb_DescriptorPool_GetDefaultPool(void);
 
+// Module-level init.
 bool PyUpb_InitDescriptorPool(PyObject* m);
 
 #endif  // PYUPB_DESCRIPTOR_POOL_H__
diff --git a/python/minimal_test.py b/python/minimal_test.py
index 0c73a4b1a8..26d6553c84 100644
--- a/python/minimal_test.py
+++ b/python/minimal_test.py
@@ -31,6 +31,10 @@ import unittest
 from google.protobuf.pyext import _message
 from google.protobuf.internal import api_implementation
 from google.protobuf import unittest_pb2
+from google.protobuf import descriptor_pool
+from google.protobuf.internal import factory_test1_pb2
+from google.protobuf.internal import factory_test2_pb2
+from google.protobuf import descriptor_pb2
 
 class TestMessageExtension(unittest.TestCase):
 
diff --git a/python/pb_unit_tests/descriptor_database_test_wrapper.py b/python/pb_unit_tests/descriptor_database_test_wrapper.py
index 69fe7de269..125533eae6 100644
--- a/python/pb_unit_tests/descriptor_database_test_wrapper.py
+++ b/python/pb_unit_tests/descriptor_database_test_wrapper.py
@@ -26,8 +26,5 @@
 from google.protobuf.internal import descriptor_database_test
 import unittest
 
-descriptor_database_test.DescriptorDatabaseTest.testAdd.__unittest_expecting_failure__ = True
-descriptor_database_test.DescriptorDatabaseTest.testConflictRegister.__unittest_expecting_failure__ = True
-
 if __name__ == '__main__':
   unittest.main(module=descriptor_database_test, verbosity=2)
diff --git a/python/pb_unit_tests/descriptor_pool_test_wrapper.py b/python/pb_unit_tests/descriptor_pool_test_wrapper.py
index 74081e0c9d..1314f1b5fa 100644
--- a/python/pb_unit_tests/descriptor_pool_test_wrapper.py
+++ b/python/pb_unit_tests/descriptor_pool_test_wrapper.py
@@ -25,49 +25,47 @@
 
 from google.protobuf.internal import descriptor_pool_test
 import unittest
+import copy
 
 print(unittest)
 
 descriptor_pool_test.AddDescriptorTest.testAddTypeError.__unittest_expecting_failure__ = True
-descriptor_pool_test.AddDescriptorTest.testCustomDescriptorPool.__unittest_expecting_failure__ = True
-descriptor_pool_test.AddDescriptorTest.testEmptyDescriptorPool.__unittest_expecting_failure__ = True
 descriptor_pool_test.AddDescriptorTest.testEnum.__unittest_expecting_failure__ = True
 descriptor_pool_test.AddDescriptorTest.testFile.__unittest_expecting_failure__ = True
 descriptor_pool_test.AddDescriptorTest.testFileDescriptorOptionsWithCustomDescriptorPool.__unittest_expecting_failure__ = True
 descriptor_pool_test.AddDescriptorTest.testMessage.__unittest_expecting_failure__ = True
 descriptor_pool_test.AddDescriptorTest.testService.__unittest_expecting_failure__ = True
+descriptor_pool_test.CreateDescriptorPoolTest.testFindFieldByName.__unittest_expecting_failure__ = True
+descriptor_pool_test.CreateDescriptorPoolTest.testFindMessageTypeByName.__unittest_expecting_failure__ = True
+descriptor_pool_test.CreateDescriptorPoolTest.testFindService.__unittest_expecting_failure__ = True
+descriptor_pool_test.CreateDescriptorPoolTest.testFindTypeErrors.__unittest_expecting_failure__ = True
+descriptor_pool_test.CreateDescriptorPoolTest.testUserDefinedDB.__unittest_expecting_failure__ = True
+descriptor_pool_test.SecondaryDescriptorFromDescriptorDB.testErrorCollector.__unittest_expecting_failure__ = True
 
-# We must skip these tests entirely (rather than running them with
-# __unittest_expecting_failure__) because they error out in setUp():
-#
-#  AttributeError: 'google.protobuf.pyext._message.FileDescriptor' object has no attribute 'serialized_pb'
-#
-# TODO: change to __unittest_expecting_failure__ when serialized_pb is available.
-descriptor_pool_test.CreateDescriptorPoolTest.testAddSerializedFile.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testComplexNesting.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testConflictRegister.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testDefaultValueForCustomMessages.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testEnumDefaultValue.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testExtensionsAreNotFields.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindAllExtensions.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindEnumTypeByName.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindEnumTypeByNameFailure.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindExtensionByName.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindExtensionByNumber.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindFieldByName.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindFileByName.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindFileByNameFailure.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindFileContainingSymbol.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindFileContainingSymbolFailure.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindMessageTypeByName.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindMessageTypeByNameFailure.__unittest_skip__ = True
-descriptor_pool_test.DefaultDescriptorPoolTest.testFindMethods.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindOneofByName.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindService.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testFindTypeErrors.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testUserDefinedDB.__unittest_skip__ = True
-descriptor_pool_test.CreateDescriptorPoolTest.testAddFileDescriptor.__unittest_skip__ = True
-descriptor_pool_test.SecondaryDescriptorFromDescriptorDB.testErrorCollector.__unittest_skip__ = True
+# Some tests are defined in a base class and inherited by multiple sub-classes.
+# If only some of the subclasses fail, we need to duplicate the test method
+# before marking it, otherwise the mark will affect all subclasses.
+def wrap(cls, method):
+  existing = getattr(cls, method)
+  setattr(cls, method, lambda self: existing(self))
+  getattr(cls, method).__unittest_expecting_failure__ = True
+
+wrap(descriptor_pool_test.CreateDescriptorPoolTest, "testAddFileDescriptor")
+wrap(descriptor_pool_test.CreateDescriptorPoolTest, "testAddSerializedFile")
+wrap(descriptor_pool_test.CreateDescriptorPoolTest, "testComplexNesting")
+wrap(descriptor_pool_test.CreateDescriptorPoolTest, "testExtensionsAreNotFields")
+wrap(descriptor_pool_test.DefaultDescriptorPoolTest, "testAddFileDescriptor")
+wrap(descriptor_pool_test.DefaultDescriptorPoolTest, "testAddSerializedFile")
+wrap(descriptor_pool_test.DefaultDescriptorPoolTest, "testComplexNesting")
+wrap(descriptor_pool_test.DefaultDescriptorPoolTest, "testEnumDefaultValue")
+wrap(descriptor_pool_test.DefaultDescriptorPoolTest, "testExtensionsAreNotFields")
+wrap(descriptor_pool_test.SecondaryDescriptorFromDescriptorDB, "testFindAllExtensions")
+wrap(descriptor_pool_test.SecondaryDescriptorFromDescriptorDB, "testFindEnumTypeByName")
+wrap(descriptor_pool_test.SecondaryDescriptorFromDescriptorDB, "testFindExtensionByName")
+wrap(descriptor_pool_test.SecondaryDescriptorFromDescriptorDB, "testFindExtensionByNumber")
+wrap(descriptor_pool_test.SecondaryDescriptorFromDescriptorDB, "testFindFileByName")
+wrap(descriptor_pool_test.SecondaryDescriptorFromDescriptorDB, "testFindFileContainingSymbol")
+wrap(descriptor_pool_test.SecondaryDescriptorFromDescriptorDB, "testFindOneofByName")
 
 if __name__ == '__main__':
   unittest.main(module=descriptor_pool_test, verbosity=2)
diff --git a/python/pb_unit_tests/descriptor_test_wrapper.py b/python/pb_unit_tests/descriptor_test_wrapper.py
index 51c5ceff9e..d34adfa2f8 100644
--- a/python/pb_unit_tests/descriptor_test_wrapper.py
+++ b/python/pb_unit_tests/descriptor_test_wrapper.py
@@ -40,46 +40,30 @@ descriptor_test.DescriptorCopyToProtoTest.testCopyToProto_TypeError.__unittest_e
 descriptor_test.GeneratedDescriptorTest.testDescriptor.__unittest_expecting_failure__ = True
 descriptor_test.MakeDescriptorTest.testCamelcaseName.__unittest_expecting_failure__ = True
 descriptor_test.MakeDescriptorTest.testJsonName.__unittest_expecting_failure__ = True
-descriptor_test.MakeDescriptorTest.testMakeDescriptorWithNestedFields.__unittest_expecting_failure__ = True
 descriptor_test.MakeDescriptorTest.testMakeDescriptorWithOptions.__unittest_expecting_failure__ = True
-descriptor_test.MakeDescriptorTest.testMakeDescriptorWithUnsignedIntField.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testAggregateOptions.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testComplexExtensionOptions.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testContainingServiceFixups.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testContainingTypeFixups.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testCustomOptionsCopyTo.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testDefault.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testDifferentCustomOptionTypes.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testEnumFixups.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testEnumValueName.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testFileDescriptor.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testFileDescriptorReferences.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testGetOptions.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testImmutableCppDescriptor.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testNestedOptions.__unittest_expecting_failure__ = True
+descriptor_test.NewDescriptorTest.testSimpleCustomOptions.__unittest_expecting_failure__ = True
 
 # We must skip these tests entirely (rather than running them with
 # __unittest_expecting_failure__) because they error out in setUp():
 #
-#  AttributeError: 'google.protobuf.pyext._message.DescriptorPool' object has no attribute 'Add'
+#  TypeError: Couldn't build proto file into descriptor pool: duplicate file name (some/filename/some.proto)
 #
-# TODO: change to __unittest_expecting_failure__ when DescriptorPool.Add() is implemented
-descriptor_test.DescriptorTest.testAggregateOptions.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testComplexExtensionOptions.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testContainingServiceFixups.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testContainingTypeFixups.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testCustomOptionsCopyTo.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testDefault.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testDifferentCustomOptionTypes.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testEnumFixups.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testEnumValueName.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testFileDescriptor.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testFileDescriptorReferences.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testGetOptions.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testImmutableCppDescriptor.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testNestedOptions.__unittest_skip__ = True
-descriptor_test.DescriptorTest.testSimpleCustomOptions.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testAggregateOptions.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testComplexExtensionOptions.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testContainingServiceFixups.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testContainingTypeFixups.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testCustomOptionsCopyTo.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testDefault.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testDifferentCustomOptionTypes.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testEnumFixups.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testEnumValueName.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testFileDescriptor.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testFileDescriptorReferences.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testGetOptions.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testImmutableCppDescriptor.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testNestedOptions.__unittest_skip__ = True
-descriptor_test.NewDescriptorTest.testSimpleCustomOptions.__unittest_skip__ = True
+# TODO: change to __unittest_expecting_failure__ when we have some solution for duplicated filenames
+descriptor_test.DescriptorTest.__unittest_skip__ = True
 
 if __name__ == '__main__':
   unittest.main(module=descriptor_test, verbosity=2)
diff --git a/python/pb_unit_tests/generator_test_wrapper.py b/python/pb_unit_tests/generator_test_wrapper.py
index daa8f95b03..ea78705494 100644
--- a/python/pb_unit_tests/generator_test_wrapper.py
+++ b/python/pb_unit_tests/generator_test_wrapper.py
@@ -28,13 +28,9 @@ import unittest
 
 generator_test.GeneratorTest.testBadIdentifiers.__unittest_expecting_failure__ = True
 generator_test.GeneratorTest.testExtensionScope.__unittest_expecting_failure__ = True
-generator_test.GeneratorTest.testFileDescriptor.__unittest_expecting_failure__ = True
 generator_test.GeneratorTest.testMessageWithCustomOptions.__unittest_expecting_failure__ = True
 generator_test.GeneratorTest.testOneof.__unittest_expecting_failure__ = True
 generator_test.GeneratorTest.testOptions.__unittest_expecting_failure__ = True
-generator_test.SymbolDatabaseRegistrationTest.testEnums.__unittest_expecting_failure__ = True
-generator_test.SymbolDatabaseRegistrationTest.testFindFileByName.__unittest_expecting_failure__ = True
-generator_test.SymbolDatabaseRegistrationTest.testGetSymbol.__unittest_expecting_failure__ = True
 
 if __name__ == '__main__':
   unittest.main(module=generator_test, verbosity=2)
diff --git a/python/pb_unit_tests/json_format_test_wrapper.py b/python/pb_unit_tests/json_format_test_wrapper.py
index 503f03fda8..8a929bd911 100644
--- a/python/pb_unit_tests/json_format_test_wrapper.py
+++ b/python/pb_unit_tests/json_format_test_wrapper.py
@@ -29,7 +29,6 @@ import unittest
 json_format_test.JsonFormatTest.testAllFieldsToJson.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testAlwaysSeriliaze.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testAnyMessage.__unittest_expecting_failure__ = True
-json_format_test.JsonFormatTest.testAnyMessageDescriptorPoolMissingType.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testDurationMessage.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testEmptyMessageToJson.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testExtensionSerializationDictMatchesProto3Spec.__unittest_expecting_failure__ = True
@@ -40,17 +39,13 @@ json_format_test.JsonFormatTest.testExtensionToDictAndBackWithScalar.__unittest_
 json_format_test.JsonFormatTest.testExtensionToJsonAndBack.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testFieldMaskMessage.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testFloatPrecision.__unittest_expecting_failure__ = True
-json_format_test.JsonFormatTest.testIgnoreUnknownField.__unittest_expecting_failure__ = True
-json_format_test.JsonFormatTest.testInvalidAny.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testInvalidMap.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testJsonEscapeString.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testJsonName.__unittest_expecting_failure__ = True
-json_format_test.JsonFormatTest.testJsonParseDictToAnyDoesNotAlterInput.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testListValueMessage.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testMapFields.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testNullValue.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testOneofFields.__unittest_expecting_failure__ = True
-json_format_test.JsonFormatTest.testParseDictAnyDescriptorPoolMissingType.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testParseNull.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testPartialMessageToJson.__unittest_expecting_failure__ = True
 json_format_test.JsonFormatTest.testStructMessage.__unittest_expecting_failure__ = True
diff --git a/python/pb_unit_tests/keywords_test_wrapper.py b/python/pb_unit_tests/keywords_test_wrapper.py
index b10d72ac4d..bca227e252 100644
--- a/python/pb_unit_tests/keywords_test_wrapper.py
+++ b/python/pb_unit_tests/keywords_test_wrapper.py
@@ -28,8 +28,6 @@ import unittest
 
 keywords_test.KeywordsConflictTest.testExtension.__unittest_expecting_failure__ = True
 keywords_test.KeywordsConflictTest.testExtensionForNestedMessage.__unittest_expecting_failure__ = True
-keywords_test.KeywordsConflictTest.testMessage.__unittest_expecting_failure__ = True
-keywords_test.KeywordsConflictTest.testNestedMessage.__unittest_expecting_failure__ = True
 
 if __name__ == '__main__':
   unittest.main(module=keywords_test, verbosity=2)
diff --git a/python/pb_unit_tests/message_factory_test_wrapper.py b/python/pb_unit_tests/message_factory_test_wrapper.py
index 9b009b660b..ad39f1d8d0 100644
--- a/python/pb_unit_tests/message_factory_test_wrapper.py
+++ b/python/pb_unit_tests/message_factory_test_wrapper.py
@@ -26,16 +26,10 @@
 from google.protobuf.internal import message_factory_test
 import unittest
 
-# We must skip these tests entirely (rather than running them with
-# __unittest_expecting_failure__) because they error out in setUp():
-#
-#  AttributeError: 'google.protobuf.pyext._message.FileDescriptor' object has no attribute 'serialized_pb'
-#
-# TODO: change to __unittest_expecting_failure__ when serialized_pb is available.
-message_factory_test.MessageFactoryTest.testCreatePrototypeOverride.__unittest_skip__ = True
-message_factory_test.MessageFactoryTest.testDuplicateExtensionNumber.__unittest_skip__ = True
-message_factory_test.MessageFactoryTest.testGetMessages.__unittest_skip__ = True
-message_factory_test.MessageFactoryTest.testGetPrototype.__unittest_skip__ = True
+message_factory_test.MessageFactoryTest.testCreatePrototypeOverride.__unittest_expecting_failure__ = True
+message_factory_test.MessageFactoryTest.testDuplicateExtensionNumber.__unittest_expecting_failure__ = True
+message_factory_test.MessageFactoryTest.testGetMessages.__unittest_expecting_failure__ = True
+message_factory_test.MessageFactoryTest.testGetPrototype.__unittest_expecting_failure__ = True
 
 if __name__ == '__main__':
   unittest.main(module=message_factory_test, verbosity=2)
diff --git a/python/pb_unit_tests/message_test_wrapper.py b/python/pb_unit_tests/message_test_wrapper.py
index 7206af1c13..53781a9f6b 100644
--- a/python/pb_unit_tests/message_test_wrapper.py
+++ b/python/pb_unit_tests/message_test_wrapper.py
@@ -94,14 +94,8 @@ message_test.Proto3Test.testScalarMap.__unittest_expecting_failure__ = True
 message_test.Proto3Test.testScalarMapDefaults.__unittest_expecting_failure__ = True
 message_test.Proto3Test.testStringUnicodeConversionInMap.__unittest_expecting_failure__ = True
 message_test.Proto3Test.testSubmessageMap.__unittest_expecting_failure__ = True
-
-# We must skip these tests entirely (rather than running them with
-# __unittest_expecting_failure__) because they error out in setUpClass():
-#
-#  AttributeError: 'google.protobuf.pyext._message.DescriptorPool' object has no attribute 'Add'
-#
-# TODO: change to __unittest_expecting_failure__ when DescriptorPoo.Add is implemented
-message_test.OversizeProtosTest.__unittest_skip__ = True
+message_test.OversizeProtosTest.testAssertOversizeProto.__unittest_expecting_failure__ = True
+message_test.OversizeProtosTest.testSucceedOversizeProto.__unittest_expecting_failure__ = True
 
 if __name__ == '__main__':
   unittest.main(module=message_test, verbosity=2)
diff --git a/python/pb_unit_tests/proto_builder_test_wrapper.py b/python/pb_unit_tests/proto_builder_test_wrapper.py
index 2da28f34f2..d189f4950e 100644
--- a/python/pb_unit_tests/proto_builder_test_wrapper.py
+++ b/python/pb_unit_tests/proto_builder_test_wrapper.py
@@ -27,9 +27,6 @@ from google.protobuf.internal import proto_builder_test
 import unittest
 
 proto_builder_test.ProtoBuilderTest.testMakeLargeProtoClass.__unittest_expecting_failure__ = True
-proto_builder_test.ProtoBuilderTest.testMakeSameProtoClassTwice.__unittest_expecting_failure__ = True
-proto_builder_test.ProtoBuilderTest.testMakeSimpleProtoClass.__unittest_expecting_failure__ = True
-proto_builder_test.ProtoBuilderTest.testOrderedFields.__unittest_expecting_failure__ = True
 
 if __name__ == '__main__':
   unittest.main(module=proto_builder_test, verbosity=2)
diff --git a/python/pb_unit_tests/reflection_test_wrapper.py b/python/pb_unit_tests/reflection_test_wrapper.py
index 42e0ac9981..a9eff07bda 100644
--- a/python/pb_unit_tests/reflection_test_wrapper.py
+++ b/python/pb_unit_tests/reflection_test_wrapper.py
@@ -35,8 +35,6 @@ reflection_test.ByteSizeTest.testPackedExtensions.__unittest_expecting_failure__
 reflection_test.ByteSizeTest.testRepeatedCompositesDelete.__unittest_expecting_failure__ = True
 reflection_test.ByteSizeTest.testRepeatedScalarsRemove.__unittest_expecting_failure__ = True
 reflection_test.ClassAPITest.testMakeClassWithNestedDescriptor.__unittest_expecting_failure__ = True
-reflection_test.ClassAPITest.testParsingFlatClass.__unittest_expecting_failure__ = True
-reflection_test.ClassAPITest.testParsingNestedClass.__unittest_expecting_failure__ = True
 reflection_test.ExtensionEqualityTest.testExtensionEquality.__unittest_expecting_failure__ = True
 reflection_test.MutualRecursionEqualityTest.testEqualityWithMutualRecursion.__unittest_expecting_failure__ = True
 reflection_test.OptionsTest.testMessageOptions.__unittest_expecting_failure__ = True
@@ -54,7 +52,6 @@ reflection_test.Proto2ReflectionTest.testMergeFromExtensionsNestedMessage.__unit
 reflection_test.Proto2ReflectionTest.testMergeFromExtensionsRepeated.__unittest_expecting_failure__ = True
 reflection_test.Proto2ReflectionTest.testMergeFromExtensionsSingular.__unittest_expecting_failure__ = True
 reflection_test.Proto2ReflectionTest.testNestedExtensions.__unittest_expecting_failure__ = True
-reflection_test.Proto2ReflectionTest.testRegisteredExtensions.__unittest_expecting_failure__ = True
 reflection_test.Proto2ReflectionTest.testRepeatedCompositeConstructor.__unittest_expecting_failure__ = True
 reflection_test.Proto2ReflectionTest.testRepeatedCompositeRemove.__unittest_expecting_failure__ = True
 reflection_test.Proto2ReflectionTest.testRepeatedCompositeReverse_Empty.__unittest_expecting_failure__ = True
diff --git a/python/pb_unit_tests/text_format_test_wrapper.py b/python/pb_unit_tests/text_format_test_wrapper.py
index f3214cf3d6..1f8f065ee3 100644
--- a/python/pb_unit_tests/text_format_test_wrapper.py
+++ b/python/pb_unit_tests/text_format_test_wrapper.py
@@ -40,7 +40,6 @@ text_format_test.OnlyWorksWithProto2RightNowTests.testPrintInIndexOrder.__unitte
 text_format_test.OnlyWorksWithProto2RightNowTests.testPrintMap.__unittest_expecting_failure__ = True
 text_format_test.OnlyWorksWithProto2RightNowTests.testPrintMapUsingCppImplementation.__unittest_expecting_failure__ = True
 text_format_test.OnlyWorksWithProto2RightNowTests.testPrintUnknownFields.__unittest_expecting_failure__ = True
-text_format_test.OptionalColonMessageToStringTest.testForcePrintOptionalColon.__unittest_expecting_failure__ = True
 text_format_test.Proto2Tests.testExtensionInsideAnyMessage.__unittest_expecting_failure__ = True
 text_format_test.Proto2Tests.testMergeDuplicateExtensionScalars.__unittest_expecting_failure__ = True
 text_format_test.Proto2Tests.testParseAllExtensions.__unittest_expecting_failure__ = True
@@ -57,19 +56,7 @@ text_format_test.Proto2Tests.testPrintAllExtensionsPointy.__unittest_expecting_f
 text_format_test.Proto2Tests.testPrintMessageSet.__unittest_expecting_failure__ = True
 text_format_test.Proto2Tests.testPrintMessageSetAsOneLine.__unittest_expecting_failure__ = True
 text_format_test.Proto2Tests.testPrintMessageSetByFieldNumber.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testMergeAlternativeUrl.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testMergeExpandedAny.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testMergeExpandedAnyDescriptorPoolMissingType.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testMergeExpandedAnyPointyBrackets.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testMergeExpandedAnyRepeated.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testMergeMissingAnyEndToken.__unittest_expecting_failure__ = True
 text_format_test.Proto3Tests.testPrintAndParseMessageInvalidAny.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testPrintMessageExpandAny.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testPrintMessageExpandAnyAsOneLine.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testPrintMessageExpandAnyAsOneLinePointyBrackets.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testPrintMessageExpandAnyDescriptorPoolMissingType.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testPrintMessageExpandAnyPointyBrackets.__unittest_expecting_failure__ = True
-text_format_test.Proto3Tests.testPrintMessageExpandAnyRepeated.__unittest_expecting_failure__ = True
 text_format_test.Proto3Tests.testTopAnyMessage.__unittest_expecting_failure__ = True
 getattr(text_format_test.TextFormatMessageToStringTests, "testCustomOptions" + sep + "0").__unittest_expecting_failure__ = True
 getattr(text_format_test.TextFormatMessageToStringTests, "testCustomOptions" + sep + "1").__unittest_expecting_failure__ = True
@@ -112,13 +99,5 @@ getattr(text_format_test.TextFormatParserTests, "testParseEmptyText" + sep + "1"
 getattr(text_format_test.TextFormatParserTests, "testParseEmptyText" + sep + "0").__unittest_expecting_failure__ = True
 getattr(text_format_test.TextFormatParserTests, "testParseEmptyText" + sep + "1").__unittest_expecting_failure__ = True
 
-# We must skip these tests entirely (rather than running them with
-# __unittest_expecting_failure__) because they error out in setUp():
-#
-#  NotImplementedError: Conversion of message types not yet implemented
-#
-# TODO: change to __unittest_expecting_failure__ when message types can be converted
-#text_format_test.WhitespaceTest.__unittest_skip__ = True
-
 if __name__ == '__main__':
   unittest.main(module=text_format_test, verbosity=2)
diff --git a/python/pb_unit_tests/unknown_fields_test_wrapper.py b/python/pb_unit_tests/unknown_fields_test_wrapper.py
index 368c06012d..f87e3f8994 100644
--- a/python/pb_unit_tests/unknown_fields_test_wrapper.py
+++ b/python/pb_unit_tests/unknown_fields_test_wrapper.py
@@ -26,12 +26,6 @@
 from google.protobuf.internal import unknown_fields_test
 import unittest
 
-# We must skip these tests entirely (rather than running them with
-# __unittest_expecting_failure__) because they error out in setUp():
-#
-#  NotImplementedError: access repeated
-#
-# TODO: change to __unittest_expecting_failure__ when repeated fields are available
 unknown_fields_test.UnknownEnumValuesTest.testCheckUnknownFieldValueForEnum.__unittest_expecting_failure__ = True
 unknown_fields_test.UnknownEnumValuesTest.testRoundTrip.__unittest_expecting_failure__ = True
 unknown_fields_test.UnknownFieldsAccessorsTest.testCheckUnknownFieldValue.__unittest_expecting_failure__ = True
diff --git a/upb/util/def_to_proto.c b/upb/util/def_to_proto.c
index fdde5cc062..71b91a258c 100644
--- a/upb/util/def_to_proto.c
+++ b/upb/util/def_to_proto.c
@@ -392,10 +392,13 @@ static google_protobuf_FileDescriptorProto *filedef_toproto(
   google_protobuf_FileDescriptorProto_set_name(
       proto, strviewdup(ctx, upb_filedef_name(f)));
 
-  size_t n = strlen(upb_filedef_package(f));
-  if (n) {
-    google_protobuf_FileDescriptorProto_set_package(
-        proto, strviewdup(ctx, upb_filedef_package(f)));
+  const char* package = upb_filedef_package(f);
+  if (package) {
+    size_t n = strlen(package);
+    if (n) {
+      google_protobuf_FileDescriptorProto_set_package(
+          proto, strviewdup(ctx, upb_filedef_package(f)));
+    }
   }
 
   if (upb_filedef_syntax(f) == UPB_SYNTAX_PROTO3) {
@@ -403,6 +406,7 @@ static google_protobuf_FileDescriptorProto *filedef_toproto(
                                                    strviewdup(ctx, "proto3"));
   }
 
+  size_t n;
   n = upb_filedef_depcount(f);
   upb_strview *deps = google_protobuf_FileDescriptorProto_resize_dependency(
       proto, n, ctx->arena);