test: Add Wallet Unlock Context Manager

Add Context Manager to manage wallet locking/unlocking with passphrase

test/functional/test_framework/wallet_util.py

@@ -122,3 +122,22 @@ def generate_keypair(compressed=True, wif=False):
     if wif:
         privkey = bytes_to_wif(privkey.get_bytes(), compressed)
     return privkey, pubkey
+
+class WalletUnlock():
+    """
+    A context manager for unlocking a wallet with a passphrase and automatically locking it afterward.
+    """
+
+    MAXIMUM_TIMEOUT = 999000
+
+    def __init__(self, wallet, passphrase, timeout=MAXIMUM_TIMEOUT):
+        self.wallet = wallet
+        self.passphrase = passphrase
+        self.timeout = timeout
+
+    def __enter__(self):
+        self.wallet.walletpassphrase(self.passphrase, self.timeout)
+
+    def __exit__(self, *args):
+        _ = args
+        self.wallet.walletlock()