message: test: Actually fix tests for serialization
diff: @@ -711,6 +711,7 @@ impl ButtplugMessage for ButtplugMessageUnion {
  }
  }
  +#[cfg(feature = "serialize_json")]
  #[cfg(test)]
  mod test {
  use super::{ButtplugMessageUnion, Error, ErrorCode, Ok};
  @@ -719,20 +720,20 @@ mod test {
  const ERROR_STR: &str =
  "{\"Error\":{\"Id\":0,\"ErrorCode\":1,\"ErrorMessage\":\"Test Error\"}}";
  - #[cfg_attr(feature = "serialize_json", test)]
  + #[test]
  fn test_ok_serialize() {
  let ok = ButtplugMessageUnion::Ok(Ok::new(0));
  let js = serde_json::to_string(&ok).unwrap();
  assert_eq!(OK_STR, js);
  }
  - #[cfg_attr(feature = "serialize_json", test)]
  + #[test]
  fn test_ok_deserialize() {
  let union: ButtplugMessageUnion = serde_json::from_str(&OK_STR).unwrap();
  assert_eq!(ButtplugMessageUnion::Ok(Ok::new(0)), union);
  }
  - #[cfg_attr(feature = "serialize_json", test)]
  + #[test]
  fn test_error_serialize() {
  let error =
  ButtplugMessageUnion::Error(Error::new(ErrorCode::ErrorHandshake, "Test Error"));
  @@ -740,7 +741,7 @@ mod test {
  assert_eq!(ERROR_STR, js);
  }
  - #[cfg_attr(feature = "serialize_json", test)]
  + #[test]
  fn test_error_deserialize() {
  let union: ButtplugMessageUnion = serde_json::from_str(&ERROR_STR).unwrap();
  assert_eq!(
  