runtime: bank: add tests for adding test builtins on feature activation

runtime/src/bank/builtin_programs.rs

@@ -3,7 +3,10 @@ mod tests {
     use {
         crate::bank::*,
         solana_sdk::{
-            ed25519_program, feature_set::FeatureSet, genesis_config::create_genesis_config,
+            ed25519_program,
+            feature::{self, Feature},
+            feature_set::FeatureSet,
+            genesis_config::create_genesis_config,
         },
     };
 
@@ -62,4 +65,73 @@ mod tests {
         // Simulate starting up from snapshot finishing the initialization for a frozen bank
         bank.finish_init(&genesis_config, None, false);
     }
+
+    #[test]
+    fn test_add_new_builtins_on_feature_activation() {
+        let check_bank_builtin_feature_activation = |builtins: &[BuiltinPrototype]| {
+            let feature_ids = builtins
+                .iter()
+                .filter_map(|builtin| builtin.feature_id)
+                .collect::<HashSet<_>>();
+
+            let mut bank = Bank::new_for_tests_with_config(
+                &GenesisConfig::default(),
+                BankTestConfig::default(),
+            );
+
+            let mut feature_set = FeatureSet::default();
+            feature_ids.iter().for_each(|feature_id| {
+                feature_set.inactive.insert(*feature_id);
+                bank.store_account(
+                    feature_id,
+                    &feature::create_account(&Feature::default(), 42),
+                );
+            });
+            bank.feature_set = Arc::new(feature_set.clone());
+
+            // Assert the builtins have not been enabled yet.
+            builtins.iter().for_each(|builtin| {
+                assert!(bank.builtin_programs.get(&builtin.program_id).is_none());
+            });
+
+            bank.apply_feature_activations(
+                ApplyFeatureActivationsCaller::NewFromParent,
+                false,
+                Some(builtins),
+            );
+
+            // Assert the builtins have been enabled.
+            builtins.iter().for_each(|builtin| {
+                assert!(bank.builtin_programs.get(&builtin.program_id).is_some());
+            });
+        };
+
+        check_bank_builtin_feature_activation(&[]);
+        check_bank_builtin_feature_activation(&[BuiltinPrototype {
+            feature_id: Some(Pubkey::new_unique()),
+            program_id: Pubkey::new_unique(),
+            name: "random_program1",
+            entrypoint: solana_system_program::system_processor::Entrypoint::vm,
+        }]);
+        check_bank_builtin_feature_activation(&[
+            BuiltinPrototype {
+                feature_id: Some(Pubkey::new_unique()),
+                program_id: Pubkey::new_unique(),
+                name: "random_program1",
+                entrypoint: solana_system_program::system_processor::Entrypoint::vm,
+            },
+            BuiltinPrototype {
+                feature_id: Some(Pubkey::new_unique()),
+                program_id: Pubkey::new_unique(),
+                name: "random_program2",
+                entrypoint: solana_system_program::system_processor::Entrypoint::vm,
+            },
+            BuiltinPrototype {
+                feature_id: Some(Pubkey::new_unique()),
+                program_id: Pubkey::new_unique(),
+                name: "random_program3",
+                entrypoint: solana_system_program::system_processor::Entrypoint::vm,
+            },
+        ]);
+    }
 }