A number of types that are `Codable` don't encode correctly

[gsabran]

Describe the bug A number of types that are Codable don't encode correctly. This seems to impact a number of the typed enums that are typically received from an OpenAI compatible server and that are not persisted by a client (unless the client would persist its requests)

For instance ChatQuery.ChatCompletionMessageParam would need a decoding such as

public init(from decoder: Decoder) throws {
    let container = try decoder.container(keyedBy: CodingKeys.self)
    let role = try container.decode(Role.self, forKey: .role)
    switch role {
    case .system:
        self = try .system(.init(from: decoder))
    case .developer:
      self = try .developer(.init(from: decoder))
    case .user:
      self = try .user(.init(from: decoder))
    case .assistant:
      self = try .assistant(.init(from: decoder))
    case .tool:
      self = try .tool(.init(from: decoder))
    }
}

I mostly look at the types in ChatQuery but typically you need to hand write the encoding / decoding for each typed enum as the generated conformances are not correct and only you know about the key used to determine which nested type is right.

As a side note, it could be helpful to have tests that validate that the encoding and decoding of those types gives back the initial value.

Lmk if you want a PR.

[nezhyborets]

Hi @gsabran thanks for the issue, you are definitely right, all the types that are Codable should decode and encode correctly. There is already a tests file that tests encoding and decoding, but it probably doesn't cover the cases you mention. It would be great if you'd make PR with the fixes