add support for return data

harness/src/fuzz/firedancer.rs

@@ -235,6 +235,7 @@ fn parse_fixture_effects(
             .compute_budget
             .compute_unit_limit
             .saturating_sub(effects.compute_units_available),
+        return_data: None, // TODO: Omitted for now.
         resulting_accounts,
     }
 }

harness/src/fuzz/mollusk.rs

@@ -94,6 +94,7 @@ impl From<&FuzzEffects> for InstructionResult {
             execution_time,
             program_result,
             raw_result,
+            return_data: None, // TODO: Omitted for now.
             resulting_accounts,
         }
     }

harness/src/lib.rs

@@ -49,9 +49,14 @@ use {
         sysvar_cache::SysvarCache,
     },
     solana_sdk::{
-        account::AccountSharedData, bpf_loader_upgradeable, feature_set::FeatureSet,
-        fee::FeeStructure, hash::Hash, instruction::Instruction, pubkey::Pubkey,
-        transaction_context::TransactionContext,
+        account::AccountSharedData,
+        bpf_loader_upgradeable,
+        feature_set::FeatureSet,
+        fee::FeeStructure,
+        hash::Hash,
+        instruction::Instruction,
+        pubkey::Pubkey,
+        transaction_context::{TransactionContext, TransactionReturnData},
     },
     solana_timings::ExecuteTimings,
     std::sync::Arc,
@@ -199,6 +204,14 @@ impl Mollusk {
             )
         };
 
+        let return_data = match transaction_context.get_return_data() {
+            (program_id, data) if !data.is_empty() => Some(TransactionReturnData {
+                program_id: *program_id,
+                data: data.to_vec(),
+            }),
+            _ => None,
+        };
+
         let resulting_accounts: Vec<(Pubkey, AccountSharedData)> = accounts
             .iter()
             .map(|(pubkey, account)| {
@@ -218,6 +231,7 @@ impl Mollusk {
             execution_time: timings.details.execute_us,
             program_result: invoke_result.clone().into(),
             raw_result: invoke_result,
+            return_data,
             resulting_accounts,
         }
     }

harness/src/result.rs

@@ -5,6 +5,7 @@ use solana_sdk::{
     instruction::InstructionError,
     program_error::ProgramError,
     pubkey::Pubkey,
+    transaction_context::TransactionReturnData,
 };
 
 /// The result code of the program's execution.
@@ -51,6 +52,8 @@ pub struct InstructionResult {
     pub program_result: ProgramResult,
     /// The raw result of the program's execution.
     pub raw_result: Result<(), InstructionError>,
+    /// The return data produced by the instruction, if any.
+    pub return_data: Option<TransactionReturnData>,
     /// The resulting accounts after executing the instruction.
     ///
     /// This includes all accounts provided to the processor, in the order
@@ -66,6 +69,7 @@ impl Default for InstructionResult {
             execution_time: 0,
             program_result: ProgramResult::Success,
             raw_result: Ok(()),
+            return_data: None,
             resulting_accounts: vec![],
         }
     }
@@ -111,6 +115,20 @@ impl InstructionResult {
                         actual_result, check_result,
                     );
                 }
+                CheckType::ReturnData(return_data) => {
+                    let check_return_data = return_data;
+                    let Some(actual_return_data) = &self.return_data else {
+                        panic!(
+                            "CHECK: return data: got None, expected {:?}",
+                            check_return_data,
+                        );
+                    };
+                    assert_eq!(
+                        actual_return_data, check_return_data,
+                        "CHECK: return_data: got {:?}, expected {:?}",
+                        actual_return_data, check_return_data,
+                    );
+                }
                 CheckType::ResultingAccount(account) => {
                     let pubkey = account.pubkey;
                     let resulting_account = self
@@ -217,6 +235,8 @@ enum CheckType<'a> {
     ExecutionTime(u64),
     /// Check the result code of the program's execution.
     ProgramResult(ProgramResult),
+    /// Check the return data produced by executing the instruction.
+    ReturnData(TransactionReturnData),
     /// Check a resulting account after executing the instruction.
     ResultingAccount(AccountCheck<'a>),
 }
@@ -255,6 +275,11 @@ impl<'a> Check<'a> {
         Check::new(CheckType::ProgramResult(ProgramResult::UnknownError(error)))
     }
 
+    /// Check the return data produced by executing the instruction.
+    pub fn return_data(return_data: TransactionReturnData) -> Self {
+        Check::new(CheckType::ReturnData(return_data))
+    }
+
     /// Check a resulting account after executing the instruction.
     pub fn account(pubkey: &Pubkey) -> AccountCheckBuilder {
         AccountCheckBuilder::new(pubkey)