Merge bitcoin/bitcoin#28617: test: Add Wallet Unlock Context Manager

004903ebad test: Add Wallet Unlock Context Manager (Brandon Odiwuor)

Pull request description:

  Fixes #28601, see https://github.com/bitcoin/bitcoin/pull/28403#discussion_r1325426430

  Add Context Manager to manage the locking and unlocking of locked wallets with a passphrase during testing.

ACKs for top commit:
  kevkevinpal:
    lgtm ACK [004903e](https://github.com/bitcoin/bitcoin/pull/28617/commits/004903ebade38ba47c5ddc17b756d605b963528e)
  maflcko:
    lgtm ACK 004903ebad

Tree-SHA512: ab234c167e71531df0d974ff9a31d444f7ce2a1d05aba5ea868cc9452f139845eeb24ca058d88f058bc02482b762adf2d99e63a6640b872cc71a57a0068abfe8

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()