From b0babf996224d5cfca4ed93bed21df47cb67cbb4 Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Tue, 29 Jun 2021 15:17:53 +0200
Subject: [PATCH] Add convenience method for signing transaction

---
 abc/transactions.nim       | 3 +++
 tests/testTransactions.nim | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/abc/transactions.nim b/abc/transactions.nim
index 92f65f8..bdf741e 100644
--- a/abc/transactions.nim
+++ b/abc/transactions.nim
@@ -67,6 +67,9 @@ func toBytes*(transaction: Transaction): seq[byte] =
 func hash*(transaction: Transaction): TxHash =
   TxHash(sha256.digest(transaction.toBytes))
 
+func sign*(key: PrivateKey, transaction: var Transaction) =
+  transaction.add(key.sign(transaction.hash.toBytes))
+
 func hasValidSignature*(transaction: Transaction): bool =
   if transaction.inputs.len == 0:
     return false
diff --git a/tests/testTransactions.nim b/tests/testTransactions.nim
index 1281328..b914022 100644
--- a/tests/testTransactions.nim
+++ b/tests/testTransactions.nim
@@ -55,6 +55,12 @@ suite "Transactions":
     transaction.add(sig2)
     check transaction.signature == aggregate(sig1, sig2)
 
+  test "transaction can be signed by a private key":
+    let key = PrivateKey.example
+    var transaction = Transaction.example
+    key.sign(transaction)
+    check transaction.signature == key.sign(transaction.hash.toBytes)
+
   test "transaction signature can be checked for validity":
     let genesis = !Transaction.init({alice: 32.u256, bob: 10.u256})
     check not genesis.hasValidSignature()