Serialize with bip70 (rust-bitcoin#19)

json/src/lib.rs

@@ -1017,6 +1017,7 @@ pub enum StringOrStringArray {
 pub struct GetBlockchainInfoResult {
     /// Current network name as defined in BIP70 (main, test, signet, regtest)
     #[serde(deserialize_with = "deserialize_bip70_network")]
+    #[serde(serialize_with = "serialize_bip70_network")]
     pub chain: Network,
     /// The current number of blocks processed in the server
     pub blocks: u64,
@@ -2190,6 +2191,13 @@ where
     Ok(Some(res))
 }
 
+fn serialize_bip70_network<S>(network: &Network, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: serde::Serializer,
+{
+    serializer.serialize_str(network.to_core_arg())
+}
+
 /// deserialize_bip70_network deserializes a Bitcoin Core network according to BIP70
 /// The accepted input variants are: {"main", "test", "signet", "regtest"}
 fn deserialize_bip70_network<'de, D>(deserializer: D) -> Result<Network, D::Error>