class_docstr: Tests for CopyTo functions of Descriptor.
code: def testCopyToProto_ForeignNestedMessage(self):
      TEST_FOREIGN_NESTED_ASCII = """
        name: 'TestForeignNested'
        field: <
          name: 'foreign_nested'
          number: 1
          label: 1  # Optional
          type: 11  # TYPE_MESSAGE
          type_name: '.protobuf_unittest.TestAllTypes.NestedMessage'
        >
        """
  
      self._InternalTestCopyToProto(
          unittest_pb2.TestForeignNested.DESCRIPTOR,
          descriptor_pb2.DescriptorProto,
          TEST_FOREIGN_NESTED_ASCII,
      )
  
imports: import sys
  from google.protobuf import unittest_custom_options_pb2
  from google.protobuf import unittest_import_pb2
  from google.protobuf import unittest_pb2
  from google.protobuf import descriptor_pb2
  from google.protobuf.internal import api_implementation
  from google.protobuf.internal import test_util
  from google.protobuf import descriptor
  from google.protobuf import descriptor_pool
  from google.protobuf import symbol_database
  from google.protobuf import text_format
label_desc: Use image node_id 5 for calling the DescriptorCopyToProtoTest obj's underlying member method code with example usage: obj.testCopyToProto_ForeignNestedMessage() without return types