From 505f77b10874ad386bc129d70afd6ad3bca0e0d7 Mon Sep 17 00:00:00 2001
From: Greg Fitzgerald <greg@solana.com>
Date: Thu, 7 Mar 2019 10:35:28 -0700
Subject: [PATCH] Move a more generic process_transaction to runtime.rs

---
 programs/budget/src/budget_program.rs | 19 ++--------------
 runtime/src/runtime.rs                | 31 ++++++++++++++++++++++++++-
 2 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/programs/budget/src/budget_program.rs b/programs/budget/src/budget_program.rs
index 7d96bdb4f..177d639ed 100644
--- a/programs/budget/src/budget_program.rs
+++ b/programs/budget/src/budget_program.rs
@@ -177,24 +177,9 @@ mod test {
         tx: &Transaction,
         tx_accounts: &mut [Account],
     ) -> Result<(), BudgetError> {
-        for ix in &tx.instructions {
-            let mut ix_accounts = runtime::get_subset_unchecked_mut(tx_accounts, &ix.accounts);
-            let mut keyed_accounts: Vec<_> = ix
-                .accounts
-                .iter()
-                .map(|&index| {
-                    let index = index as usize;
-                    let key = &tx.account_keys[index];
-                    (key, index < tx.signatures.len())
-                })
-                .zip(ix_accounts.iter_mut())
-                .map(|((key, is_signer), account)| KeyedAccount::new(key, is_signer, account))
-                .collect();
-
-            process_instruction(&mut keyed_accounts, &ix.userdata)?;
-        }
-        Ok(())
+        runtime::process_transaction(tx, tx_accounts, process_instruction)
     }
+
     #[test]
     fn test_invalid_instruction() {
         let mut accounts = vec![Account::new(1, 0, id()), Account::new(0, 512, id())];
diff --git a/runtime/src/runtime.rs b/runtime/src/runtime.rs
index 26b706109..2ef8f9216 100644
--- a/runtime/src/runtime.rs
+++ b/runtime/src/runtime.rs
@@ -143,7 +143,7 @@ pub fn has_duplicates<T: PartialEq>(xs: &[T]) -> bool {
 }
 
 /// Get mut references to a subset of elements.
-pub fn get_subset_unchecked_mut<'a, T>(xs: &'a mut [T], indexes: &[u8]) -> Vec<&'a mut T> {
+fn get_subset_unchecked_mut<'a, T>(xs: &'a mut [T], indexes: &[u8]) -> Vec<&'a mut T> {
     // Since the compiler doesn't know the indexes are unique, dereferencing
     // multiple mut elements is assumed to be unsafe. If, however, all
     // indexes are unique, it's perfectly safe. The returned elements will share
@@ -188,6 +188,35 @@ pub fn execute_transaction(
     Ok(())
 }
 
+/// A utility function for unit-tests. Same as execute_transaction(), but bypasses the loaders
+/// for easier usage and better stack traces.
+pub fn process_transaction<F, E>(
+    tx: &Transaction,
+    tx_accounts: &mut [Account],
+    process_instruction: F,
+) -> Result<(), E>
+where
+    F: Fn(&mut [KeyedAccount], &[u8]) -> Result<(), E>,
+{
+    for ix in &tx.instructions {
+        let mut ix_accounts = get_subset_unchecked_mut(tx_accounts, &ix.accounts);
+        let mut keyed_accounts: Vec<_> = ix
+            .accounts
+            .iter()
+            .map(|&index| {
+                let index = index as usize;
+                let key = &tx.account_keys[index];
+                (key, index < tx.signatures.len())
+            })
+            .zip(ix_accounts.iter_mut())
+            .map(|((key, is_signer), account)| KeyedAccount::new(key, is_signer, account))
+            .collect();
+
+        process_instruction(&mut keyed_accounts, &ix.userdata)?;
+    }
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;