diff --git a/codegen/opentelemetry-codegen-json/tests/test_types.py b/codegen/opentelemetry-codegen-json/tests/test_types.py
index a9d8a4eee5e..1e0f8dacdb3 100644
--- a/codegen/opentelemetry-codegen-json/tests/test_types.py
+++ b/codegen/opentelemetry-codegen-json/tests/test_types.py
@@ -3,10 +3,15 @@
 
 # pylint: disable=no-member
 
+import ast
+import builtins
+
 import pytest  # type: ignore
 from google.protobuf import descriptor_pb2 as descriptor
 
 from opentelemetry.codegen.json.types import (
+    PROTO_DEFAULTS,
+    PROTO_TO_PYTHON,
     get_default_value,
     get_json_allowed_types,
     get_python_type,
@@ -17,15 +22,17 @@
     to_json_field_name,
 )
 
+FDP = descriptor.FieldDescriptorProto
+
 
 @pytest.mark.parametrize(
     "proto_type, expected",
     [
-        (descriptor.FieldDescriptorProto.TYPE_DOUBLE, "builtins.float"),
-        (descriptor.FieldDescriptorProto.TYPE_INT64, "builtins.int"),
-        (descriptor.FieldDescriptorProto.TYPE_BOOL, "builtins.bool"),
-        (descriptor.FieldDescriptorProto.TYPE_STRING, "builtins.str"),
-        (descriptor.FieldDescriptorProto.TYPE_BYTES, "builtins.bytes"),
+        (FDP.TYPE_DOUBLE, "builtins.float"),
+        (FDP.TYPE_INT64, "builtins.int"),
+        (FDP.TYPE_BOOL, "builtins.bool"),
+        (FDP.TYPE_STRING, "builtins.str"),
+        (FDP.TYPE_BYTES, "builtins.bytes"),
     ],
 )
 def test_get_python_type(proto_type: int, expected: str) -> None:
@@ -35,28 +42,56 @@ def test_get_python_type(proto_type: int, expected: str) -> None:
 @pytest.mark.parametrize(
     "proto_type, expected",
     [
-        (descriptor.FieldDescriptorProto.TYPE_DOUBLE, "0.0"),
-        (descriptor.FieldDescriptorProto.TYPE_INT64, "0"),
-        (descriptor.FieldDescriptorProto.TYPE_BOOL, "False"),
-        (descriptor.FieldDescriptorProto.TYPE_STRING, '""'),
-        (descriptor.FieldDescriptorProto.TYPE_BYTES, 'b""'),
-        (999, "None"),
+        (FDP.TYPE_DOUBLE, "0.0"),
+        (FDP.TYPE_FLOAT, "0.0"),
+        (FDP.TYPE_INT64, "0"),
+        (FDP.TYPE_UINT32, "0"),
+        (FDP.TYPE_SINT64, "0"),
+        (FDP.TYPE_BOOL, "False"),
+        (FDP.TYPE_STRING, '""'),
+        (FDP.TYPE_BYTES, 'b""'),
     ],
 )
 def test_get_default_value(proto_type: int, expected: str) -> None:
     assert get_default_value(proto_type) == expected
 
 
+@pytest.mark.parametrize(
+    "proto_type",
+    [FDP.TYPE_GROUP, FDP.TYPE_MESSAGE, FDP.TYPE_ENUM],
+)
+def test_get_default_value_types_without_default(proto_type: int) -> None:
+    assert get_default_value(proto_type) == "None"
+
+
+@pytest.mark.parametrize("proto_type", [0, -1, 999, 2**31])
+def test_get_default_value_out_of_range(proto_type: int) -> None:
+    assert get_default_value(proto_type) == "None"
+
+
+def test_every_mapped_type_has_a_default() -> None:
+    # keeps PROTO_TO_PYTHON and PROTO_DEFAULTS from drifting apart
+    assert set(PROTO_TO_PYTHON) == set(PROTO_DEFAULTS)
+
+
+@pytest.mark.parametrize("proto_type", PROTO_DEFAULTS)
+def test_default_is_valid_python_literal(proto_type: int) -> None:
+    # the default is emitted into generated code, so it must parse cleanly
+    value = ast.literal_eval(get_default_value(proto_type))
+    type_name = get_python_type(proto_type).removeprefix("builtins.")
+    assert isinstance(value, getattr(builtins, type_name))
+
+
 @pytest.mark.parametrize(
     "proto_type, expected",
     [
-        (descriptor.FieldDescriptorProto.TYPE_INT64, True),
-        (descriptor.FieldDescriptorProto.TYPE_UINT64, True),
-        (descriptor.FieldDescriptorProto.TYPE_FIXED64, True),
-        (descriptor.FieldDescriptorProto.TYPE_SFIXED64, True),
-        (descriptor.FieldDescriptorProto.TYPE_SINT64, True),
-        (descriptor.FieldDescriptorProto.TYPE_INT32, False),
-        (descriptor.FieldDescriptorProto.TYPE_STRING, False),
+        (FDP.TYPE_INT64, True),
+        (FDP.TYPE_UINT64, True),
+        (FDP.TYPE_FIXED64, True),
+        (FDP.TYPE_SFIXED64, True),
+        (FDP.TYPE_SINT64, True),
+        (FDP.TYPE_INT32, False),
+        (FDP.TYPE_STRING, False),
     ],
 )
 def test_is_int64_type(proto_type: int, expected: bool) -> None:
@@ -66,8 +101,8 @@ def test_is_int64_type(proto_type: int, expected: bool) -> None:
 @pytest.mark.parametrize(
     "proto_type, expected",
     [
-        (descriptor.FieldDescriptorProto.TYPE_BYTES, True),
-        (descriptor.FieldDescriptorProto.TYPE_STRING, False),
+        (FDP.TYPE_BYTES, True),
+        (FDP.TYPE_STRING, False),
     ],
 )
 def test_is_bytes_type(proto_type: int, expected: bool) -> None:
@@ -104,11 +139,11 @@ def test_to_json_field_name(snake_name: str, expected: str) -> None:
 @pytest.mark.parametrize(
     "proto_type, expected",
     [
-        (descriptor.FieldDescriptorProto.TYPE_DOUBLE, True),
-        (descriptor.FieldDescriptorProto.TYPE_INT64, True),
-        (descriptor.FieldDescriptorProto.TYPE_INT32, True),
-        (descriptor.FieldDescriptorProto.TYPE_BOOL, False),
-        (descriptor.FieldDescriptorProto.TYPE_STRING, False),
+        (FDP.TYPE_DOUBLE, True),
+        (FDP.TYPE_INT64, True),
+        (FDP.TYPE_INT32, True),
+        (FDP.TYPE_BOOL, False),
+        (FDP.TYPE_STRING, False),
     ],
 )
 def test_is_numeric_type(proto_type: int, expected: bool) -> None:
@@ -118,25 +153,19 @@ def test_is_numeric_type(proto_type: int, expected: bool) -> None:
 @pytest.mark.parametrize(
     "proto_type, field_name, expected",
     [
-        (descriptor.FieldDescriptorProto.TYPE_BYTES, "data", "builtins.str"),
-        (
-            descriptor.FieldDescriptorProto.TYPE_STRING,
-            "trace_id",
-            "builtins.str",
-        ),
-        (
-            descriptor.FieldDescriptorProto.TYPE_INT64,
-            "count",
-            "(builtins.int, builtins.str)",
-        ),
+        (FDP.TYPE_BYTES, "data", "builtins.str"),
+        (FDP.TYPE_STRING, "trace_id", "builtins.str"),
+        (FDP.TYPE_INT64, "count", "(builtins.int, builtins.str)"),
         (
-            descriptor.FieldDescriptorProto.TYPE_DOUBLE,
+            FDP.TYPE_DOUBLE,
             "value",
             "(builtins.float, builtins.int, builtins.str)",
         ),
-        (descriptor.FieldDescriptorProto.TYPE_BOOL, "flag", "builtins.bool"),
-        (descriptor.FieldDescriptorProto.TYPE_INT32, "id", "builtins.int"),
+        (FDP.TYPE_BOOL, "flag", "builtins.bool"),
+        (FDP.TYPE_INT32, "id", "builtins.int"),
     ],
 )
-def test_get_json_allowed_types(proto_type: int, field_name: str, expected: str) -> None:
-    assert get_json_allowed_types(proto_type, field_name) == expected
+def test_get_json_allowed_types(
+    proto_type: int, field_name: str, expected: str
+) -> None:
+    assert get_json_allowed_types(proto_type, field_name) == expected
\ No newline at end of file