test: misc interface_ipc_mining.py improvements

- clarify run_ipc_option_override_test description: https://github.com/bitcoin/bitcoin/pull/33965#discussion_r2784515535
- trailing comma after includes: https://github.com/bitcoin/bitcoin/pull/34452#discussion_r2775183035
- include order: https://github.com/bitcoin/bitcoin/pull/34452#discussion_r2774730966
- reuse the shared miniwallet in the low block height test: https://github.com/bitcoin/bitcoin/pull/34860#discussion_r3255163123

test/functional/interface_ipc_mining.py

@@ -9,35 +9,35 @@ from contextlib import AsyncExitStack
 from io import BytesIO
 from test_framework.blocktools import NULL_OUTPOINT, script_BIP34_coinbase_height
 from test_framework.messages import (
-    MAX_BLOCK_WEIGHT,
     CBlockHeader,
+    COIN,
     CTransaction,
     CTxIn,
-    CTxOut,
     CTxInWitness,
-    ser_uint256,
-    COIN,
+    CTxOut,
+    MAX_BLOCK_WEIGHT,
     from_hex,
     msg_headers,
+    ser_uint256,
 )
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
     assert_greater_than_or_equal,
-    assert_not_equal
+    assert_not_equal,
 )
 from test_framework.wallet import MiniWallet
 from test_framework.p2p import P2PInterface
 from test_framework.ipc_util import (
+    assert_capnp_failed,
     destroying,
-    mining_create_block_template,
     load_capnp_modules,
+    make_mining_ctx,
+    mining_create_block_template,
     mining_get_block,
     mining_get_coinbase_tx,
     mining_wait_next_template,
     wait_and_do,
-    make_mining_ctx,
-    assert_capnp_failed
 )
 
 # Test may be skipped and not have capnp installed
@@ -291,8 +291,9 @@ class IPCMiningTest(BitcoinTestFramework):
 
     def run_ipc_option_override_test(self):
         self.log.info("Running IPC option override test")
-        # Set an absurd reserved weight. `-blockreservedweight` is RPC-only, so
-        # with this setting RPC templates would be empty. IPC clients set
+        # Confirm that BlockCreateOptions.blockReservedWeight takes precedence
+        # over -blockreservedweight. Set an absurdly high -blockreservedweight
+        # value that would result in empty blocks to verify this. IPC clients set
         # blockReservedWeight per template request and are unaffected; later in
         # the test the IPC template includes a mempool transaction.
         self.restart_node(0, extra_args=[f"-blockreservedweight={MAX_BLOCK_WEIGHT}"])
@@ -421,8 +422,6 @@ class IPCMiningTest(BitcoinTestFramework):
         node.wait_for_rpc_connection()
         assert_equal(node.getblockcount(), 0)
 
-        miniwallet = MiniWallet(node)
-
         async def async_routine():
             ctx, mining = await make_mining_ctx(self)
             opts = self.capnp_modules['mining'].BlockCreateOptions()
@@ -437,7 +436,7 @@ class IPCMiningTest(BitcoinTestFramework):
                     block = await mining_get_block(template, ctx)
                     # Heights <= 16 need extra nonce padding.
                     extra_nonce = b'\xaa\xbb\xcc\xdd' if height <= 16 else b""
-                    coinbase = await self.build_coinbase_test(template, ctx, miniwallet, extra_nonce=extra_nonce)
+                    coinbase = await self.build_coinbase_test(template, ctx, self.miniwallet, extra_nonce=extra_nonce)
                     block.vtx[0] = coinbase
                     block.hashMerkleRoot = block.calc_merkle_root()
                     block.solve()