[program-test] adding method warp_to_epoch (#34620)

* [program-test] adding method warp_to_epoch

* formatting fix

program-test/src/lib.rs

@@ -30,7 +30,7 @@ use {
     solana_sdk::{
         account::{create_account_shared_data_for_test, Account, AccountSharedData},
         account_info::AccountInfo,
-        clock::Slot,
+        clock::{Epoch, Slot},
         entrypoint::{deserialize, ProgramResult, SUCCESS},
         feature_set::FEATURE_NAMES,
         fee_calculator::{FeeCalculator, FeeRateGovernor, DEFAULT_TARGET_LAMPORTS_PER_SIGNATURE},
@@ -1207,6 +1207,14 @@ impl ProgramTestContext {
         Ok(())
     }
 
+    pub fn warp_to_epoch(&mut self, warp_epoch: Epoch) -> Result<(), ProgramTestError> {
+        let warp_slot = self
+            .genesis_config
+            .epoch_schedule
+            .get_first_slot_in_epoch(warp_epoch);
+        self.warp_to_slot(warp_slot)
+    }
+
     /// warp forward one more slot and force reward interval end
     pub fn warp_forward_force_reward_interval_end(&mut self) -> Result<(), ProgramTestError> {
         let mut bank_forks = self.bank_forks.write().unwrap();

program-test/tests/warp.rs

@@ -369,8 +369,15 @@ async fn stake_merge_immediately_after_activation() {
     check_credits_observed(&mut context.banks_client, base_stake_address, 100).await;
     context.increment_vote_account_credits(&vote_address, 100);
 
+    let clock_account = context
+        .banks_client
+        .get_account(clock::id())
+        .await
+        .expect("account exists")
+        .unwrap();
+    let clock: Clock = deserialize(&clock_account.data).unwrap();
+    context.warp_to_epoch(clock.epoch + 1).unwrap();
     current_slot += slots_per_epoch;
-    context.warp_to_slot(current_slot).unwrap();
     context.warp_forward_force_reward_interval_end().unwrap();
 
     // make another stake which will just have its credits observed advanced