Use JSON (de)serializers instead of custom ones for tests

Tests/GRPCInProcessTransportTests/InProcessTransportTests.swift

@@ -80,7 +80,7 @@ struct InProcessTransportTests {
         request: ClientRequest(message: ()),
         descriptor: .peerInfo,
         serializer: VoidSerializer(),
-        deserializer: PeerInfoDeserializer(),
+        deserializer: JSONDeserializer<PeerInfo>(),
         options: .defaults
       ) {
         try $0.message
@@ -142,7 +142,7 @@ private struct TestService: RegistrableRPCService {
     router.registerHandler(
       forMethod: .peerInfo,
       deserializer: VoidDeserializer(),
-      serializer: PeerInfoSerializer(),
+      serializer: JSONSerializer<PeerInfo>(),
       handler: {
         let response = try await self.peerInfo(
           request: ServerRequest<Void>(stream: $0),
@@ -171,22 +171,6 @@ private struct PeerInfo: Codable {
   var remote: String
 }
 
-private struct PeerInfoSerializer: MessageSerializer {
-  func serialize<Bytes: GRPCContiguousBytes>(_ message: PeerInfo) throws -> Bytes {
-    Bytes("\(message.local) \(message.remote)".utf8)
-  }
-}
-
-private struct PeerInfoDeserializer: MessageDeserializer {
-  func deserialize<Bytes: GRPCContiguousBytes>(_ serializedMessageBytes: Bytes) throws -> PeerInfo {
-    let stringPeerInfo = serializedMessageBytes.withUnsafeBytes {
-      String(decoding: $0, as: UTF8.self)
-    }
-    let peerInfoComponents = stringPeerInfo.split(separator: " ")
-    return PeerInfo(local: String(peerInfoComponents[0]), remote: String(peerInfoComponents[1]))
-  }
-}
-
 private struct UTF8Serializer: MessageSerializer {
   func serialize<Bytes: GRPCContiguousBytes>(_ message: String) throws -> Bytes {
     Bytes(message.utf8)

Tests/GRPCInProcessTransportTests/Test Utilities/JSONSerializing.swift

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2025, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import Foundation
+import GRPCCore
+
+struct JSONSerializer<Message: Encodable>: MessageSerializer {
+  private let encoder = JSONEncoder()
+
+  func serialize(_ message: Message) throws -> [UInt8] {
+    let data = try self.encoder.encode(message)
+    return Array(data)
+  }
+}
+
+struct JSONDeserializer<Message: Decodable>: MessageDeserializer {
+  private let decoder = JSONDecoder()
+
+  func deserialize(_ serializedMessageBytes: [UInt8]) throws -> Message {
+    try self.decoder.decode(Message.self, from: Data(serializedMessageBytes))
+  }
+}