Implementation of the pick_first LB policy

grpc/src/client/load_balancing/mod.rs

@@ -54,6 +54,9 @@
 pub mod child_manager;
 pub mod pick_first;
 
+#[cfg(test)]
+pub mod test_utils;
+
 pub(crate) mod registry;
 use super::{service_config::LbConfig, subchannel::SubchannelStateWatcher};
 pub(crate) use registry::{LbPolicyRegistry, GLOBAL_LB_REGISTRY};
@@ -89,7 +92,7 @@
     pub fn new(json: &str) -> Result<Self, String> {
         match serde_json::from_str(json) {
             Ok(value) => Ok(ParsedJsonLbConfig { value }),
             Err(e) => Err(format!("failed to parse LB config JSON: {}", e)),
         }
     }
 
@@ -108,7 +111,7 @@
         let res: T = match serde_json::from_value(self.value.clone()) {
             Ok(v) => v,
             Err(e) => {
                 return Err(format!("{}", e).into());
             }
         };
         Ok(res)
@@ -209,7 +212,7 @@
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(f, "connectivity_state: {}", self.connectivity_state)?;
         if let Some(err) = &self.last_connection_error {
             write!(f, ", last_connection_error: {}", err)?;
         }
         Ok(())
     }