message: do not use POOL constant
diff: @@ -769,7 +769,6 @@ pub mod tests {
  const SIMPLE_REPLY: &'static str = r#"{"result":{}}"#;
  const REJECT_REPLY: &'static str = r#"{"op":"REJECT", "result": {"reason": "reject"}}"#;
  const NACK_REPLY: &'static str = r#"{"op":"REQNACK", "result": {"reason": "reqnack"}}"#;
  - const POOL: &'static str = "pool1";
  #[derive(Debug)]
  pub struct MockRequestHandler {}
  @@ -879,7 +878,7 @@ pub mod tests {
  let mut path = environment::pool_path(pool_name);
  - path.push(POOL);
  + path.push(pool_name);
  path.set_extension("txn");
  fs::create_dir_all(path.parent().unwrap()).unwrap();
  