4 files changed, 65 insertions(+), 5 deletions(-)

M runtime/pb/json.lua
M runtime/pb/wkt.lua
M test/conformance/known_failures.txt
M test/conformance_test.lua

@@ 33,9 33,13 @@ local INT64_FAMILY = {int64=true, uint64=true, sint64=true, fixed64=true, sfixed
 -- Helpers
 -- ---------------------------------------------------------------------------
 
--- snake_case -> camelCase (proto field naming convention for JSON).
+-- snake_case -> lowerCamelCase per the proto3 JSON spec. Multi-underscore
+-- runs collapse to one capitalized letter; trailing underscores drop. A
+-- leading underscore causes the next letter to be capitalized so the JSON
+-- name has no leading underscore (e.g. `_field_name3` → `FieldName3`).
 local function to_camel(name)
-    return (name:gsub('_(%w)', function(c) return c:upper() end))
+    name = name:gsub('_+$', '')
+    return (name:gsub('_+(%w)', function(c) return c:upper() end))
 end
 
 -- Lossless stringification of an integer/cdata for JSON output.

@@ 254,6 254,17 @@ end
 local NULL = box.NULL
 M.NULL = NULL
 
+-- google.protobuf.NullValue is a singleton enum (NULL_VALUE = 0). It shows
+-- up as the type of Value's null_value field and as a standalone enum
+-- field type (e.g. oneof_null_value in the conformance test message). We
+-- export a minimal descriptor so the codec layer can route enum decode
+-- through enum.by_name lookups instead of crashing on a nil descriptor.
+M.NullValue_descriptor = {
+    name = 'google.protobuf.NullValue',
+    by_name = {NULL_VALUE = 0},
+    by_value = {[0] = 'NULL_VALUE'},
+}
+
 local STRUCT_MT = {__pb_kind = 'struct'}
 local LIST_MT   = {__pb_kind = 'list'}
 

@@ 18,15 18,12 @@
 #     because of the global JSON-output skip.
 #
 # Re-generate this file after fixes via `just conformance-refresh-failures`.
-Recommended.Proto3.JsonInput.FieldNameWithDoubleUnderscores.ProtobufOutput
-Recommended.Proto3.JsonInput.NullValueInOtherOneofOldFormat.Validator
 Required.Proto3.JsonInput.AllFieldAcceptNull.JsonOutput
 Required.Proto3.JsonInput.AnyNested.JsonOutput
 Required.Proto3.JsonInput.AnyWithInt32ValueWrapper.JsonOutput
 Required.Proto3.JsonInput.AnyWithStruct.JsonOutput
 Required.Proto3.JsonInput.AnyWithValueForInteger.JsonOutput
 Required.Proto3.JsonInput.AnyWithValueForJsonObject.JsonOutput
-Required.Proto3.JsonInput.FieldNameInSnakeCase.ProtobufOutput
 Required.Proto3.JsonInput.Int64FieldMaxValueNotQuoted.JsonOutput
 Required.Proto3.JsonInput.Int64FieldMaxValueNotQuoted.ProtobufOutput
 Required.Proto3.JsonInput.Int64FieldMinValueNotQuoted.JsonOutput

@@ 689,6 689,54 @@ core_g.test_null_value_field_emits_null_value_member = function()
     t.assert_equals(resp.protobuf_payload, '\x92\x13\x02\x08\x00')
 end
 
+-- =========================================================================
+-- Fix 10: lower-camelCase mapping for JSON field names. The proto3 spec
+-- collapses runs of underscores (`__`) and drops trailing underscores; a
+-- leading underscore causes capitalization of the next letter so the
+-- generated JSON name has no leading underscore.
+-- =========================================================================
+
+core_g.test_json_decode_camel_case_drops_double_underscore = function()
+    -- field 404 = field__name4_ → canonical JSON name "fieldName4".
+    -- tag = (404<<3)|0 = 3232 → varint 0xa0 0x19. Plus value varint.
+    local resp = json_to_pb([[{"fieldName4": 4}]])
+    t.assert_not(resp.parse_error, resp.parse_error)
+    t.assert_equals(resp.protobuf_payload, '\xa0\x19\x04')
+end
+
+core_g.test_json_decode_camel_case_leading_underscore_capitalizes = function()
+    -- field 403 = _field_name3 → canonical "FieldName3".
+    -- tag = (403<<3)|0 = 3224 → varint 0x98 0x19.
+    local resp = json_to_pb([[{"FieldName3": 3}]])
+    t.assert_not(resp.parse_error, resp.parse_error)
+    t.assert_equals(resp.protobuf_payload, '\x98\x19\x03')
+end
+
+core_g.test_json_decode_camel_case_trailing_underscore_drops = function()
+    -- field 417 = field_name17__ → canonical "fieldName17".
+    -- tag = (417<<3)|0 = 3336 → varint 0x88 0x1a.
+    local resp = json_to_pb([[{"fieldName17": 17}]])
+    t.assert_not(resp.parse_error, resp.parse_error)
+    t.assert_equals(resp.protobuf_payload, '\x88\x1a\x11')
+end
+
+-- =========================================================================
+-- Fix 11: google.protobuf.NullValue descriptor exposed so enum fields
+-- whose type is NullValue (e.g. oneof_null_value, or Value.null_value)
+-- can be decoded from JSON without indexing a nil descriptor.
+-- =========================================================================
+
+core_g.test_oneof_null_value_decodes_from_json = function()
+    -- oneof_null_value is the singleton enum NullValue (NULL_VALUE=0). With
+    -- the descriptor in place, decode_enum can resolve "NULL_VALUE" → 0.
+    -- Field 120, tag (120<<3)|0 = 960 → varint 0xc0 0x07. Value 0 elides.
+    -- Empty payload is the expected output for a 0-valued enum in a oneof
+    -- — except this is a oneof branch with explicit presence, so it WILL
+    -- emit. Either way, we want no parse_error.
+    local resp = json_to_pb([[{"oneofNullValue": "NULL_VALUE"}]])
+    t.assert_not(resp.parse_error, resp.parse_error)
+end
+
 core_g.test_oneof_merge_still_clears_sibling_branches = function()
     -- The post-fix merge code must still clear oneof siblings: setting
     -- oneof_uint32 first, then merging two oneof_nested_message entries,