Adds a direct check of the cached entries around recompilation.

program-runtime/src/loaded_programs.rs

@@ -1076,6 +1076,14 @@ impl<FG: ForkGraph> LoadedPrograms<FG> {
         }
     }
 
+    /// Returns the `slot_versions` of the second level for the given program id.
+    pub fn get_slot_versions_for_tests(&self, key: &Pubkey) -> &[Arc<LoadedProgram>] {
+        self.entries
+            .get(key)
+            .map(|second_level| second_level.slot_versions.as_ref())
+            .unwrap_or(&[])
+    }
+
     /// This function removes the given entry for the given program from the cache.
     /// The function expects that the program and entry exists in the cache. Otherwise it'll panic.
     fn unload_program_entry(&mut self, program: &Pubkey, remove_entry: &Arc<LoadedProgram>) {

runtime/src/bank/tests.rs

@@ -11935,10 +11935,48 @@ fn test_feature_activation_loaded_programs_recompilation_phase() {
     // Advance the bank to middle of epoch to start the recompilation phase.
     goto_end_of_slot(bank.clone());
     let bank = new_bank_from_parent_with_bank_forks(&bank_forks, bank, &Pubkey::default(), 16);
+    let current_env = bank
+        .loaded_programs_cache
+        .read()
+        .unwrap()
+        .get_environments_for_epoch(0)
+        .program_runtime_v1
+        .clone();
+    let upcoming_env = bank
+        .loaded_programs_cache
+        .read()
+        .unwrap()
+        .get_environments_for_epoch(1)
+        .program_runtime_v1
+        .clone();
 
     // Advance the bank to recompile the program.
+    {
+        let loaded_programs_cache = bank.loaded_programs_cache.read().unwrap();
+        let slot_versions =
+            loaded_programs_cache.get_slot_versions_for_tests(&program_keypair.pubkey());
+        assert_eq!(slot_versions.len(), 1);
+        assert!(Arc::ptr_eq(
+            &slot_versions[0].program.get_environment().unwrap(),
+            &current_env
+        ));
+    }
     goto_end_of_slot(bank.clone());
     let bank = new_from_parent_with_fork_next_slot(bank, bank_forks.as_ref());
+    {
+        let loaded_programs_cache = bank.loaded_programs_cache.read().unwrap();
+        let slot_versions =
+            loaded_programs_cache.get_slot_versions_for_tests(&program_keypair.pubkey());
+        assert_eq!(slot_versions.len(), 2);
+        assert!(Arc::ptr_eq(
+            &slot_versions[0].program.get_environment().unwrap(),
+            &current_env
+        ));
+        assert!(Arc::ptr_eq(
+            &slot_versions[1].program.get_environment().unwrap(),
+            &upcoming_env
+        ));
+    }
 
     // Advance the bank to cross the epoch boundary and activate the feature.
     goto_end_of_slot(bank.clone());