Adding upstream version 1.2+20240521.

Signed-off-by: Daniel Baumann <daniel@debian.org>

tests/inputs/proto3_field_presence_oneof/proto3_field_presence_oneof.json

@@ -0,0 +1,3 @@
+{
+  "nested": {}
+}

tests/inputs/proto3_field_presence_oneof/proto3_field_presence_oneof.proto

@@ -0,0 +1,22 @@
+syntax = "proto3";
+
+package proto3_field_presence_oneof;
+
+message Test {
+    oneof kind {
+        Nested nested = 1;
+        WithOptional with_optional = 2;
+    }
+}
+
+message InnerNested {
+    optional bool a = 1;
+}
+
+message Nested {
+    InnerNested inner = 1;
+}
+
+message WithOptional {
+    optional bool b = 2;
+}

tests/inputs/proto3_field_presence_oneof/test_proto3_field_presence_oneof.py

@@ -0,0 +1,29 @@
+from tests.output_aristaproto.proto3_field_presence_oneof import (
+    InnerNested,
+    Nested,
+    Test,
+    WithOptional,
+)
+
+
+def test_serialization():
+    """Ensure that serialization of fields unset but with explicit field
+    presence do not bloat the serialized payload with length-delimited fields
+    with length 0"""
+
+    def test_empty_nested(message: Test) -> None:
+        # '0a' => tag 1, length delimited
+        # '00' => length: 0
+        assert bytes(message) == bytearray.fromhex("0a 00")
+
+    test_empty_nested(Test(nested=Nested()))
+    test_empty_nested(Test(nested=Nested(inner=None)))
+    test_empty_nested(Test(nested=Nested(inner=InnerNested(a=None))))
+
+    def test_empty_with_optional(message: Test) -> None:
+        # '12' => tag 2, length delimited
+        # '00' => length: 0
+        assert bytes(message) == bytearray.fromhex("12 00")
+
+    test_empty_with_optional(Test(with_optional=WithOptional()))
+    test_empty_with_optional(Test(with_optional=WithOptional(b=None)))