code review comments

chain/ethereum/src/ingestor.rs

@@ -78,7 +78,7 @@ impl PollingBlockIngestor {
         // To check if there is a new block or not, fetch only the block header since that's cheaper
         // than the full block. This is worthwhile because most of the time there won't be a new
         // block, as we expect the poll interval to be much shorter than the block time.
-        let latest_block = self.latest_block(&logger, &eth_adapter).await?;
+        let latest_block = self.latest_block(logger, &eth_adapter).await?;
 
         if let Some(head_block) = head_block_ptr_opt.as_ref() {
             // If latest block matches head block in store, nothing needs to be done

chain/ethereum/src/network.rs

@@ -80,7 +80,7 @@ pub struct EthereumNetworkAdapters {
 }
 
 impl EthereumNetworkAdapters {
-    pub fn empty() -> Self {
+    pub fn empty_for_testing() -> Self {
         Self {
             chain_id: "".into(),
             manager: ProviderManager::default(),
@@ -150,6 +150,9 @@ impl EthereumNetworkAdapters {
             .filter(|adapter| adapter.get_capacity() > AvailableCapacity::Unavailable)
     }
 
+    /// returns all the available adapters that meet the required capabilities
+    /// if no adapters are available at the time or none that meet the capabilities then
+    /// an empty iterator is returned.
     pub async fn all_cheapest_with(
         &self,
         required_capabilities: &NodeCapabilities,
@@ -164,7 +167,7 @@ impl EthereumNetworkAdapters {
     }
 
     // get all the adapters, don't trigger the ProviderManager's validations because we want
-    // this function to remain sync
+    // this function to remain sync. If no adapters are available an empty iterator is returned.
     pub(crate) fn all_unverified_cheapest_with(
         &self,
         required_capabilities: &NodeCapabilities,

node/src/chain.rs

@@ -426,7 +426,7 @@ pub async fn networks_as_chains(
                 (k, BlockchainKind::Substreams) => k,
                 (k, _) => k,
             })
-            .expect("each chain should have at least 1 adapter");
+            .expect("validation should have checked we have at least one provider");
         (chain_id, adapters, kind)
     });
     for (chain_id, adapters, kind) in chains.into_iter() {

tests/src/fixture/ethereum.rs

@@ -45,7 +45,7 @@ pub async fn chain(
     let static_block_stream = Arc::new(StaticStreamBuilder { chain: blocks });
     let block_stream_builder = Arc::new(MutexBlockStreamBuilder(Mutex::new(static_block_stream)));
 
-    let eth_adapters = Arc::new(EthereumNetworkAdapters::empty());
+    let eth_adapters = Arc::new(EthereumNetworkAdapters::empty_for_testing());
 
     let chain = Chain::new(
         logger_factory,