auction: add auction_id_exists helper

crates/core/component/auction/src/component/auction.rs

@@ -6,6 +6,8 @@ use std::sync::Arc;
 use tendermint::v0_37::abci;
 use tracing::instrument;
 
+use crate::{auction::id::AuctionId, state_key};
+
 pub struct Auction {}
 impl Auction {}
 
@@ -43,7 +45,15 @@ impl Component for Auction {
 
 /// Extension trait providing read access to auction data.
 #[async_trait]
-pub trait StateReadExt: StateRead {}
+pub trait StateReadExt: StateRead {
+    /// Returns `true` if the suppied `auction_id` is already used.
+    async fn auction_id_exists(&self, auction_id: AuctionId) -> bool {
+        self.get_raw(&state_key::auction_store::by_id(auction_id))
+            .await
+            .expect("no storage errors")
+            .map_or(false, |_| true)
+    }
+}
 
 impl<T: StateRead + ?Sized> StateReadExt for T {}