feat: added AllRentExempt check (#140)

Author: deanmlittle

harness/tests/bpf_program.rs

@@ -159,10 +159,56 @@ fn test_transfer() {
             Check::account(&recipient)
                 .lamports(recipient_lamports + transfer_amount)
                 .build(),
+            Check::all_rent_exempt(),
         ],
     );
 }
 
+#[test]
+#[should_panic(
+    expected = "Account 4vJ9JU1bJJE96FWSJKvHsmmFADCg4gpZQff4P3bkLKi is not rent exempt after \
+                execution (lamports: 1, data_len: 0)"
+)]
+fn test_non_rent_exempt_transfer() {
+    std::env::set_var("SBF_OUT_DIR", "../target/deploy");
+
+    let program_id = Pubkey::new_unique();
+
+    let mollusk = Mollusk::new(&program_id, "test_program_primary");
+
+    let payer = Pubkey::new_unique();
+    let payer_lamports = 100_000_000;
+    let payer_account = Account::new(payer_lamports, 0, &solana_sdk_ids::system_program::id());
+
+    // Use deterministic address for explicit panic matching
+    let recipient = Pubkey::new_from_array([0x01; 32]);
+
+    let instruction_non_rent_exempt = {
+        let mut instruction_data = vec![2];
+        instruction_data.extend_from_slice(&1u64.to_le_bytes());
+        Instruction::new_with_bytes(
+            program_id,
+            &instruction_data,
+            vec![
+                AccountMeta::new(payer, true),
+                AccountMeta::new(recipient, false),
+                AccountMeta::new_readonly(solana_sdk_ids::system_program::id(), false),
+            ],
+        )
+    };
+
+    // Fail non-rent-exempt account.
+    mollusk.process_and_validate_instruction(
+        &instruction_non_rent_exempt,
+        &[
+            (payer, payer_account.clone()),
+            (recipient, Account::default()),
+            keyed_account_for_system_program(),
+        ],
+        &[Check::all_rent_exempt()],
+    );
+}
+
 #[test]
 fn test_close_account() {
     std::env::set_var("SBF_OUT_DIR", "../target/deploy");

result/src/check.rs

@@ -22,6 +22,8 @@ enum CheckType<'a> {
     ReturnData(&'a [u8]),
     /// Check a resulting account after executing the instruction.
     ResultingAccount(AccountCheck<'a>),
+    /// Check that all accounts are rent exempt
+    AllRentExempt,
 }
 
 pub struct Check<'a> {
@@ -72,6 +74,11 @@ impl<'a> Check<'a> {
     pub fn account(pubkey: &Pubkey) -> AccountCheckBuilder {
         AccountCheckBuilder::new(pubkey)
     }
+
+    /// Check that all resulting accounts are rent exempt
+    pub fn all_rent_exempt() -> Self {
+        Check::new(CheckType::AllRentExempt)
+    }
 }
 
 enum AccountStateCheck {
@@ -271,6 +278,22 @@ impl InstructionResult {
                             compare!(c, "account_data_slice", check_data_slice, actual_data_slice,);
                     }
                 }
+                CheckType::AllRentExempt => {
+                    for (pubkey, account) in &self.resulting_accounts {
+                        let is_rent_exempt =
+                            context.is_rent_exempt(account.lamports(), account.data().len());
+                        if !is_rent_exempt {
+                            pass &= throw!(
+                                c,
+                                "Account {} is not rent exempt after execution (lamports: {}, \
+                                 data_len: {})",
+                                pubkey,
+                                account.lamports(),
+                                account.data().len()
+                            );
+                        }
+                    }
+                }
             }
         }
         pass