test-validator: Add flag to clone feature set from a cluster (#2480)

* test-validator: Add flag to clone feature set from a cluster

#### Problem

Program devs run into issues when testing, where everything works great
with a solana-test-validator, and then fails once they deploy to a real
cluster. Most times, this happens because the test validator enables all
features by default, and their program depended on a new feature without
their knowledge.

#### Summary of changes

To make local development much easier, add a `--clone-feature-set` flag
to solana-test-validator to easily mimic the functionality on the
cluster targeted with `--url`.

* Add changelog entry

CHANGELOG.md

@@ -23,6 +23,7 @@ Release channels have their own copy of this changelog:
 * Changes
   * SDK: removed the `respan` macro. This was marked as "internal use only" and was no longer used internally.
   * `agave-validator`: Update PoH speed check to compare against current hash rate from a Bank (#2447)
+  * `solana-test-validator`: Add `--clone-feature-set` flag to mimic features from a target cluster (#2480)
 
 ## [2.0.0]
 * Breaking

test-validator/src/lib.rs

@@ -43,6 +43,7 @@ use {
         commitment_config::CommitmentConfig,
         epoch_schedule::EpochSchedule,
         exit::Exit,
+        feature,
         feature_set::FEATURE_NAMES,
         fee_calculator::FeeRateGovernor,
         instruction::{AccountMeta, Instruction},
@@ -428,6 +429,32 @@ impl TestValidatorGenesis {
         Ok(self)
     }
 
+    pub fn clone_feature_set(&mut self, rpc_client: &RpcClient) -> Result<&mut Self, String> {
+        for feature_ids in FEATURE_NAMES
+            .keys()
+            .cloned()
+            .collect::<Vec<Pubkey>>()
+            .chunks(MAX_MULTIPLE_ACCOUNTS)
+        {
+            rpc_client
+                .get_multiple_accounts(feature_ids)
+                .map_err(|err| format!("Failed to fetch: {err}"))?
+                .into_iter()
+                .zip(feature_ids)
+                .for_each(|(maybe_account, feature_id)| {
+                    if maybe_account
+                        .as_ref()
+                        .and_then(feature::from_account)
+                        .and_then(|feature| feature.activated_at)
+                        .is_none()
+                    {
+                        self.deactivate_feature_set.insert(*feature_id);
+                    }
+                });
+        }
+        Ok(self)
+    }
+
     pub fn add_accounts_from_json_files(
         &mut self,
         accounts: &[AccountInfo],

validator/src/bin/solana-test-validator.rs

@@ -281,6 +281,8 @@ fn main() {
             .map(|v| v.into_iter().collect())
             .unwrap_or_default();
 
+    let clone_feature_set = matches.is_present("clone_feature_set");
+
     let warp_slot = if matches.is_present("warp_slot") {
         Some(match matches.value_of("warp_slot") {
             Some(_) => value_t_or_exit!(matches, "warp_slot", Slot),
@@ -511,6 +513,17 @@ fn main() {
         }
     }
 
+    if clone_feature_set {
+        if let Err(e) = genesis.clone_feature_set(
+            cluster_rpc_client
+                .as_ref()
+                .expect("bug: --url argument missing?"),
+        ) {
+            println!("Error: clone_feature_set failed: {e}");
+            exit(1);
+        }
+    }
+
     if let Some(warp_slot) = warp_slot {
         genesis.warp_slot(warp_slot);
     }

validator/src/cli.rs

@@ -2811,6 +2811,17 @@ pub fn test_app<'a>(version: &'a str, default_args: &'a DefaultTestArgs) -> App<
                 .validator(is_parsable::<u64>)
                 .takes_value(true)
                 .help("Override the runtime's account lock limit per transaction"),
+        )
+        .arg(
+            Arg::with_name("clone_feature_set")
+                .long("clone-feature-set")
+                .takes_value(false)
+                .requires("json_rpc_url")
+                .help(
+                    "Copy a feature set from the cluster referenced by the --url \
+                     argument in the genesis configuration. If the ledger \
+                     already exists then this parameter is silently ignored",
+                ),
         );
 }