use genesis_hash as first checkpoint when checkpoints are missing for…

… configured testnets too

zebra-consensus/src/checkpoint/list.rs

@@ -64,15 +64,10 @@ impl ParameterCheckpoint for Network {
     }
 
     fn checkpoint_list(&self) -> CheckpointList {
-        let checkpoints_for_network = match self {
-            Network::Mainnet => MAINNET_CHECKPOINTS,
-            Network::Testnet(params) if !params.is_regtest() => TESTNET_CHECKPOINTS,
-            // Returns only the genesis checkpoint for Regtest
-            Network::Testnet(_params) => {
-                // It's okay to skip checking the hard-coded genesis checkpoint is the genesis checkpoint
-                return CheckpointList::from_list([(block::Height(0), self.genesis_hash())])
-                    .expect("hard-coded checkpoint list parses and validates");
-            }
+        let (checkpoints_for_network, should_fallback_to_genesis_hash_as_checkpoint) = match self {
+            Network::Mainnet => (MAINNET_CHECKPOINTS, false),
+            Network::Testnet(params) if params.is_default_testnet() => (TESTNET_CHECKPOINTS, false),
+            Network::Testnet(_params) => (TESTNET_CHECKPOINTS, true),
         };
 
         // Check that the list starts with the correct genesis block and parses checkpoint list.
@@ -87,6 +82,10 @@ impl ParameterCheckpoint for Network {
             Ok((block::Height(0), hash)) if hash == self.genesis_hash() => checkpoints_for_network
                 .parse()
                 .expect("hard-coded checkpoint list parses and validates"),
+            _ if should_fallback_to_genesis_hash_as_checkpoint => {
+                CheckpointList::from_list([(block::Height(0), self.genesis_hash())])
+                    .expect("hard-coded checkpoint list parses and validates")
+            }
             Ok((block::Height(0), _)) => {
                 panic!("the genesis checkpoint does not match the Mainnet or Testnet genesis hash")
             }