test: use MiniWallet for mining_prioritisetransaction.py

This test can now be run even with the Bitcoin Core wallet disabled.

test/functional/test_framework/util.py

@@ -552,24 +552,22 @@ def gen_return_txouts():
 
 # Create a spend of each passed-in utxo, splicing in "txouts" to each raw
 # transaction to make it large.  See gen_return_txouts() above.
-def create_lots_of_big_transactions(node, txouts, utxos, num, fee):
-    addr = node.getnewaddress()
+def create_lots_of_big_transactions(mini_wallet, node, fee, tx_batch_size, txouts, utxos=None):
+    from .messages import COIN
+    fee_sats = int(fee * COIN)
     txids = []
-    from .messages import tx_from_hex
-    for _ in range(num):
-        t = utxos.pop()
-        inputs = [{"txid": t["txid"], "vout": t["vout"]}]
-        outputs = {}
-        change = t['amount'] - fee
-        outputs[addr] = satoshi_round(change)
-        rawtx = node.createrawtransaction(inputs, outputs)
-        tx = tx_from_hex(rawtx)
-        for txout in txouts:
-            tx.vout.append(txout)
-        newtx = tx.serialize().hex()
-        signresult = node.signrawtransactionwithwallet(newtx, None, "NONE")
-        txid = node.sendrawtransaction(signresult["hex"], 0)
-        txids.append(txid)
+    use_internal_utxos = utxos is None
+    for _ in range(tx_batch_size):
+        tx = mini_wallet.create_self_transfer(
+                from_node=node,
+                utxo_to_spend=None if use_internal_utxos else utxos.pop(),
+                fee_rate=0,
+                mempool_valid=False)['tx']
+        tx.vout[0].nValue -= fee_sats
+        tx.vout.extend(txouts)
+        res = node.testmempoolaccept([tx.serialize().hex()])[0]
+        assert_equal(res['fees']['base'], fee)
+        txids.append(node.sendrawtransaction(tx.serialize().hex()))
     return txids