refactor: test: use _ variable for unused loop counters

substitutes "for x in range(N):" by "for _ in range(N):"
indicates to the reader that a block is just repeated N times, and
that the loop counter is not used in the body

35 files changed, 83 insertions, 83 deletions

diff --git a/test/functional/example_test.py b/test/functional/example_test.py
index 5d782026dc..34e4999329 100755
--- a/test/functional/example_test.py
+++ b/test/functional/example_test.py
@@ -166,7 +166,7 @@ class ExampleTest(BitcoinTestFramework):
 
         height = self.nodes[0].getblockcount()
 
-        for i in range(10):
+        for _ in range(10):
             # Use the mininode and blocktools functionality to manually build a block
             # Calling the generate() rpc is easier, but this allows us to exactly
             # control the blocks and transactions.
diff --git a/test/functional/feature_assumevalid.py b/test/functional/feature_assumevalid.py
index 79777f5582..f19ee12f95 100755
--- a/test/functional/feature_assumevalid.py
+++ b/test/functional/feature_assumevalid.py
@@ -123,7 +123,7 @@ class AssumeValidTest(BitcoinTestFramework):
         height += 1
 
         # Bury the block 100 deep so the coinbase output is spendable
-        for i in range(100):
+        for _ in range(100):
             block = create_block(self.tip, create_coinbase(height), self.block_time)
             block.solve()
             self.blocks.append(block)
@@ -149,7 +149,7 @@ class AssumeValidTest(BitcoinTestFramework):
         height += 1
 
         # Bury the assumed valid block 2100 deep
-        for i in range(2100):
+        for _ in range(2100):
             block = create_block(self.tip, create_coinbase(height), self.block_time)
             block.nVersion = 4
             block.solve()
diff --git a/test/functional/feature_bip68_sequence.py b/test/functional/feature_bip68_sequence.py
index 19cdc10935..1253c45418 100755
--- a/test/functional/feature_bip68_sequence.py
+++ b/test/functional/feature_bip68_sequence.py
@@ -141,7 +141,7 @@ class BIP68Test(BitcoinTestFramework):
         # some of those inputs to be sequence locked (and randomly choose
         # between height/time locking). Small random chance of making the locks
         # all pass.
-        for i in range(400):
+        for _ in range(400):
             # Randomly choose up to 10 inputs
             num_inputs = random.randint(1, 10)
             random.shuffle(utxos)
@@ -260,7 +260,7 @@ class BIP68Test(BitcoinTestFramework):
         # Use prioritisetransaction to lower the effective feerate to 0
         self.nodes[0].prioritisetransaction(txid=tx2.hash, fee_delta=int(-self.relayfee*COIN))
         cur_time = int(time.time())
-        for i in range(10):
+        for _ in range(10):
             self.nodes[0].setmocktime(cur_time + 600)
             self.nodes[0].generate(1)
             cur_time += 600
diff --git a/test/functional/feature_block.py b/test/functional/feature_block.py
index 6619d83dc4..c74761869b 100755
--- a/test/functional/feature_block.py
+++ b/test/functional/feature_block.py
@@ -125,7 +125,7 @@ class FullBlockTest(BitcoinTestFramework):
 
         # collect spendable outputs now to avoid cluttering the code later on
         out = []
-        for i in range(NUM_OUTPUTS_TO_COLLECT):
+        for _ in range(NUM_OUTPUTS_TO_COLLECT):
             out.append(self.get_spendable_output())
 
         # Start by building a couple of blocks on top (which output is spent is
diff --git a/test/functional/feature_csv_activation.py b/test/functional/feature_csv_activation.py
index c6852ef017..dfb3683143 100755
--- a/test/functional/feature_csv_activation.py
+++ b/test/functional/feature_csv_activation.py
@@ -161,7 +161,7 @@ class BIP68_112_113Test(BitcoinTestFramework):
 
     def generate_blocks(self, number):
         test_blocks = []
-        for i in range(number):
+        for _ in range(number):
             block = self.create_test_block([])
             test_blocks.append(block)
             self.last_block_time += 600
@@ -209,22 +209,22 @@ class BIP68_112_113Test(BitcoinTestFramework):
         # Note we reuse inputs for v1 and v2 txs so must test these separately
         # 16 normal inputs
         bip68inputs = []
-        for i in range(16):
+        for _ in range(16):
             bip68inputs.append(send_generic_input_tx(self.nodes[0], self.coinbase_blocks, self.nodeaddress))
 
         # 2 sets of 16 inputs with 10 OP_CSV OP_DROP (actually will be prepended to spending scriptSig)
         bip112basicinputs = []
-        for j in range(2):
+        for _ in range(2):
             inputs = []
-            for i in range(16):
+            for _ in range(16):
                 inputs.append(send_generic_input_tx(self.nodes[0], self.coinbase_blocks, self.nodeaddress))
             bip112basicinputs.append(inputs)
 
         # 2 sets of 16 varied inputs with (relative_lock_time) OP_CSV OP_DROP (actually will be prepended to spending scriptSig)
         bip112diverseinputs = []
-        for j in range(2):
+        for _ in range(2):
             inputs = []
-            for i in range(16):
+            for _ in range(16):
                 inputs.append(send_generic_input_tx(self.nodes[0], self.coinbase_blocks, self.nodeaddress))
             bip112diverseinputs.append(inputs)
 
diff --git a/test/functional/feature_dbcrash.py b/test/functional/feature_dbcrash.py
index 7b38e09bf9..7a2e35c095 100755
--- a/test/functional/feature_dbcrash.py
+++ b/test/functional/feature_dbcrash.py
@@ -195,7 +195,7 @@ class ChainstateWriteCrashTest(BitcoinTestFramework):
         while len(utxo_list) >= 2 and num_transactions < count:
             tx = CTransaction()
             input_amount = 0
-            for i in range(2):
+            for _ in range(2):
                 utxo = utxo_list.pop()
                 tx.vin.append(CTxIn(COutPoint(int(utxo['txid'], 16), utxo['vout'])))
                 input_amount += int(utxo['amount'] * COIN)
@@ -205,7 +205,7 @@ class ChainstateWriteCrashTest(BitcoinTestFramework):
                 # Sanity check -- if we chose inputs that are too small, skip
                 continue
 
-            for i in range(3):
+            for _ in range(3):
                 tx.vout.append(CTxOut(output_amount, hex_str_to_bytes(utxo['scriptPubKey'])))
 
             # Sign and send the transaction to get into the mempool
diff --git a/test/functional/feature_fee_estimation.py b/test/functional/feature_fee_estimation.py
index 3cf0fb8f7b..702a1d9995 100755
--- a/test/functional/feature_fee_estimation.py
+++ b/test/functional/feature_fee_estimation.py
@@ -176,9 +176,9 @@ class EstimateFeeTest(BitcoinTestFramework):
         # We shuffle our confirmed txout set before each set of transactions
         # small_txpuzzle_randfee will use the transactions that have inputs already in the chain when possible
         # resorting to tx's that depend on the mempool when those run out
-        for i in range(numblocks):
+        for _ in range(numblocks):
             random.shuffle(self.confutxo)
-            for j in range(random.randrange(100 - 50, 100 + 50)):
+            for _ in range(random.randrange(100 - 50, 100 + 50)):
                 from_index = random.randint(1, 2)
                 (txhex, fee) = small_txpuzzle_randfee(self.nodes[from_index], self.confutxo,
                                                       self.memutxo, Decimal("0.005"), min_fee, min_fee)
@@ -243,7 +243,7 @@ class EstimateFeeTest(BitcoinTestFramework):
         self.confutxo = self.txouts  # Start with the set of confirmed txouts after splitting
         self.log.info("Will output estimates for 1/2/3/6/15/25 blocks")
 
-        for i in range(2):
+        for _ in range(2):
             self.log.info("Creating transactions and mining them with a block size that can't keep up")
             # Create transactions and mine 10 small blocks with node 2, but create txs faster than we can mine
             self.transact_and_mine(10, self.nodes[2])
diff --git a/test/functional/feature_maxuploadtarget.py b/test/functional/feature_maxuploadtarget.py
index 5538d6d3b4..0dc2839191 100755
--- a/test/functional/feature_maxuploadtarget.py
+++ b/test/functional/feature_maxuploadtarget.py
@@ -104,7 +104,7 @@ class MaxUploadTest(BitcoinTestFramework):
         assert_equal(len(self.nodes[0].getpeerinfo()), 3)
         # At most a couple more tries should succeed (depending on how long
         # the test has been running so far).
-        for i in range(3):
+        for _ in range(3):
             p2p_conns[0].send_message(getdata_request)
         p2p_conns[0].wait_for_disconnect()
         assert_equal(len(self.nodes[0].getpeerinfo()), 2)
diff --git a/test/functional/feature_pruning.py b/test/functional/feature_pruning.py
index e46e5aacc8..02fa88f7c8 100755
--- a/test/functional/feature_pruning.py
+++ b/test/functional/feature_pruning.py
@@ -147,7 +147,7 @@ class PruneTest(BitcoinTestFramework):
         # Create stale blocks in manageable sized chunks
         self.log.info("Mine 24 (stale) blocks on Node 1, followed by 25 (main chain) block reorg from Node 0, for 12 rounds")
 
-        for j in range(12):
+        for _ in range(12):
             # Disconnect node 0 so it can mine a longer reorg chain without knowing about node 1's soon-to-be-stale chain
             # Node 2 stays connected, so it hears about the stale blocks and then reorg's when node0 reconnects
             disconnect_nodes(self.nodes[0], 1)
diff --git a/test/functional/feature_rbf.py b/test/functional/feature_rbf.py
index acf551ef69..1b531ad51d 100755
--- a/test/functional/feature_rbf.py
+++ b/test/functional/feature_rbf.py
@@ -376,7 +376,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
         split_value = int((initial_nValue-fee)/(MAX_REPLACEMENT_LIMIT+1))
 
         outputs = []
-        for i in range(MAX_REPLACEMENT_LIMIT+1):
+        for _ in range(MAX_REPLACEMENT_LIMIT+1):
             outputs.append(CTxOut(split_value, CScript([1])))
 
         splitting_tx = CTransaction()
diff --git a/test/functional/feature_segwit.py b/test/functional/feature_segwit.py
index 5195d20dcb..0842972779 100755
--- a/test/functional/feature_segwit.py
+++ b/test/functional/feature_segwit.py
@@ -126,11 +126,11 @@ class SegWitTest(BitcoinTestFramework):
             assert_equal(bip173_ms_addr, script_to_p2wsh(multiscript))
             p2sh_ids.append([])
             wit_ids.append([])
-            for v in range(2):
+            for _ in range(2):
                 p2sh_ids[i].append([])
                 wit_ids[i].append([])
 
-        for i in range(5):
+        for _ in range(5):
             for n in range(3):
                 for v in range(2):
                     wit_ids[n][v].append(send_to_witness(v, self.nodes[0], find_spendable_utxo(self.nodes[0], 50), self.pubkey[n], False, Decimal("49.999")))
diff --git a/test/functional/mempool_package_onemore.py b/test/functional/mempool_package_onemore.py
index 0739d7e29b..e956fe07d2 100755
--- a/test/functional/mempool_package_onemore.py
+++ b/test/functional/mempool_package_onemore.py
@@ -31,7 +31,7 @@ class MempoolPackagesTest(BitcoinTestFramework):
         for (txid, vout) in zip(parent_txids, vouts):
             inputs.append({'txid' : txid, 'vout' : vout})
         outputs = {}
-        for i in range(num_outputs):
+        for _ in range(num_outputs):
             outputs[node.getnewaddress()] = send_value
         rawtx = node.createrawtransaction(inputs, outputs, 0, True)
         signedtx = node.signrawtransactionwithwallet(rawtx)
diff --git a/test/functional/mempool_packages.py b/test/functional/mempool_packages.py
index 542d24f4be..98dac30ace 100755
--- a/test/functional/mempool_packages.py
+++ b/test/functional/mempool_packages.py
@@ -48,7 +48,7 @@ class MempoolPackagesTest(BitcoinTestFramework):
         send_value = satoshi_round((value - fee)/num_outputs)
         inputs = [ {'txid' : parent_txid, 'vout' : vout} ]
         outputs = {}
-        for i in range(num_outputs):
+        for _ in range(num_outputs):
             outputs[node.getnewaddress()] = send_value
         rawtx = node.createrawtransaction(inputs, outputs)
         signedtx = node.signrawtransactionwithwallet(rawtx)
@@ -70,7 +70,7 @@ class MempoolPackagesTest(BitcoinTestFramework):
         # MAX_ANCESTORS transactions off a confirmed tx should be fine
         chain = []
         witness_chain = []
-        for i in range(MAX_ANCESTORS):
+        for _ in range(MAX_ANCESTORS):
             (txid, sent_value) = self.chain_transaction(self.nodes[0], txid, 0, value, fee, 1)
             value = sent_value
             chain.append(txid)
@@ -245,7 +245,7 @@ class MempoolPackagesTest(BitcoinTestFramework):
 
         # Sign and send up to MAX_DESCENDANT transactions chained off the parent tx
         chain = [] # save sent txs for the purpose of checking node1's mempool later (see below)
-        for i in range(MAX_DESCENDANTS - 1):
+        for _ in range(MAX_DESCENDANTS - 1):
             utxo = transaction_package.pop(0)
             (txid, sent_value) = self.chain_transaction(self.nodes[0], utxo['txid'], utxo['vout'], utxo['amount'], fee, 10)
             chain.append(txid)
@@ -312,7 +312,7 @@ class MempoolPackagesTest(BitcoinTestFramework):
         send_value = satoshi_round((value - fee)/2)
         inputs = [ {'txid' : txid, 'vout' : vout} ]
         outputs = {}
-        for i in range(2):
+        for _ in range(2):
             outputs[self.nodes[0].getnewaddress()] = send_value
         rawtx = self.nodes[0].createrawtransaction(inputs, outputs)
         signedtx = self.nodes[0].signrawtransactionwithwallet(rawtx)
@@ -326,7 +326,7 @@ class MempoolPackagesTest(BitcoinTestFramework):
         # Create tx2-7
         vout = 1
         txid = tx0_id
-        for i in range(6):
+        for _ in range(6):
             (txid, sent_value) = self.chain_transaction(self.nodes[0], txid, vout, value, fee, 1)
             vout = 0
             value = sent_value
diff --git a/test/functional/mempool_persist.py b/test/functional/mempool_persist.py
index 5d00648aed..85c4d6d570 100755
--- a/test/functional/mempool_persist.py
+++ b/test/functional/mempool_persist.py
@@ -62,7 +62,7 @@ class MempoolPersistTest(BitcoinTestFramework):
     def run_test(self):
         self.log.debug("Send 5 transactions from node2 (to its own address)")
         tx_creation_time_lower = int(time.time())
-        for i in range(5):
+        for _ in range(5):
             last_txid = self.nodes[2].sendtoaddress(self.nodes[2].getnewaddress(), Decimal("10"))
         node2_balance = self.nodes[2].getbalance()
         self.sync_all()
diff --git a/test/functional/mempool_updatefromblock.py b/test/functional/mempool_updatefromblock.py
index 8a703ef009..8baf974a0a 100755
--- a/test/functional/mempool_updatefromblock.py
+++ b/test/functional/mempool_updatefromblock.py
@@ -73,7 +73,7 @@ class MempoolUpdateFromBlockTest(BitcoinTestFramework):
                 n_outputs = size - tx_count
                 output_value = ((inputs_value - fee) / Decimal(n_outputs)).quantize(Decimal('0.00000001'))
                 outputs = {}
-                for n in range(0, n_outputs):
+                for _ in range(n_outputs):
                     outputs[self.nodes[0].getnewaddress()] = output_value
             else:
                 output_value = (inputs_value - fee).quantize(Decimal('0.00000001'))
diff --git a/test/functional/p2p_compactblocks.py b/test/functional/p2p_compactblocks.py
index 0b3738b572..71457ba988 100755
--- a/test/functional/p2p_compactblocks.py
+++ b/test/functional/p2p_compactblocks.py
@@ -125,7 +125,7 @@ class CompactBlocksTest(BitcoinTestFramework):
         out_value = total_value // 10
         tx = CTransaction()
         tx.vin.append(CTxIn(COutPoint(block.vtx[0].sha256, 0), b''))
-        for i in range(10):
+        for _ in range(10):
             tx.vout.append(CTxOut(out_value, CScript([OP_TRUE])))
         tx.rehash()
 
@@ -266,7 +266,7 @@ class CompactBlocksTest(BitcoinTestFramework):
         address = node.getnewaddress()
 
         segwit_tx_generated = False
-        for i in range(num_transactions):
+        for _ in range(num_transactions):
             txid = node.sendtoaddress(address, 0.1)
             hex_tx = node.gettransaction(txid)["hex"]
             tx = FromHex(CTransaction(), hex_tx)
@@ -418,7 +418,7 @@ class CompactBlocksTest(BitcoinTestFramework):
     def build_block_with_transactions(self, node, utxo, num_transactions):
         block = self.build_block_on_tip(node)
 
-        for i in range(num_transactions):
+        for _ in range(num_transactions):
             tx = CTransaction()
             tx.vin.append(CTxIn(COutPoint(utxo[0], utxo[1]), b''))
             tx.vout.append(CTxOut(utxo[2] - 1000, CScript([OP_TRUE, OP_DROP] * 15 + [OP_TRUE])))
@@ -627,7 +627,7 @@ class CompactBlocksTest(BitcoinTestFramework):
         # Test that requesting old compactblocks doesn't work.
         MAX_CMPCTBLOCK_DEPTH = 5
         new_blocks = []
-        for i in range(MAX_CMPCTBLOCK_DEPTH + 1):
+        for _ in range(MAX_CMPCTBLOCK_DEPTH + 1):
             test_node.clear_block_announcement()
             new_blocks.append(node.generate(1)[0])
             wait_until(test_node.received_block_announcement, timeout=30, lock=mininode_lock)
diff --git a/test/functional/p2p_feefilter.py b/test/functional/p2p_feefilter.py
index 73afe9adc4..0b51d8f4bb 100755
--- a/test/functional/p2p_feefilter.py
+++ b/test/functional/p2p_feefilter.py
@@ -19,7 +19,7 @@ def hashToHex(hash):
 
 # Wait up to 60 secs to see if the testnode has received all the expected invs
 def allInvsMatch(invsExpected, testnode):
-    for x in range(60):
+    for _ in range(60):
         with mininode_lock:
             if (sorted(invsExpected) == sorted(testnode.txinvs)):
                 return True
@@ -91,7 +91,7 @@ class FeeFilterTest(BitcoinTestFramework):
         # Test that invs are received by test connection for all txs at
         # feerate of .2 sat/byte
         node1.settxfee(Decimal("0.00000200"))
-        txids = [node1.sendtoaddress(node1.getnewaddress(), 1) for x in range(3)]
+        txids = [node1.sendtoaddress(node1.getnewaddress(), 1) for _ in range(3)]
         assert allInvsMatch(txids, conn)
         conn.clear_invs()
 
@@ -100,14 +100,14 @@ class FeeFilterTest(BitcoinTestFramework):
 
         # Test that txs are still being received by test connection (paying .15 sat/byte)
         node1.settxfee(Decimal("0.00000150"))
-        txids = [node1.sendtoaddress(node1.getnewaddress(), 1) for x in range(3)]
+        txids = [node1.sendtoaddress(node1.getnewaddress(), 1) for _ in range(3)]
         assert allInvsMatch(txids, conn)
         conn.clear_invs()
 
         # Change tx fee rate to .1 sat/byte and test they are no longer received
         # by the test connection
         node1.settxfee(Decimal("0.00000100"))
-        [node1.sendtoaddress(node1.getnewaddress(), 1) for x in range(3)]
+        [node1.sendtoaddress(node1.getnewaddress(), 1) for _ in range(3)]
         self.sync_mempools()  # must be sure node 0 has received all txs
 
         # Send one transaction from node0 that should be received, so that we
@@ -124,7 +124,7 @@ class FeeFilterTest(BitcoinTestFramework):
 
         # Remove fee filter and check that txs are received again
         conn.send_and_ping(msg_feefilter(0))
-        txids = [node1.sendtoaddress(node1.getnewaddress(), 1) for x in range(3)]
+        txids = [node1.sendtoaddress(node1.getnewaddress(), 1) for _ in range(3)]
         assert allInvsMatch(txids, conn)
         conn.clear_invs()
 
diff --git a/test/functional/p2p_segwit.py b/test/functional/p2p_segwit.py
index 728212ca23..d70c32d8f3 100755
--- a/test/functional/p2p_segwit.py
+++ b/test/functional/p2p_segwit.py
@@ -942,7 +942,7 @@ class SegWitTest(BitcoinTestFramework):
         parent_tx = CTransaction()
         parent_tx.vin.append(CTxIn(prevout, b""))
         child_value = int(value / NUM_OUTPUTS)
-        for i in range(NUM_OUTPUTS):
+        for _ in range(NUM_OUTPUTS):
             parent_tx.vout.append(CTxOut(child_value, script_pubkey))
         parent_tx.vout[0].nValue -= 50000
         assert parent_tx.vout[0].nValue > 0
@@ -952,7 +952,7 @@ class SegWitTest(BitcoinTestFramework):
         for i in range(NUM_OUTPUTS):
             child_tx.vin.append(CTxIn(COutPoint(parent_tx.sha256, i), b""))
         child_tx.vout = [CTxOut(value - 100000, CScript([OP_TRUE]))]
-        for i in range(NUM_OUTPUTS):
+        for _ in range(NUM_OUTPUTS):
             child_tx.wit.vtxinwit.append(CTxInWitness())
             child_tx.wit.vtxinwit[-1].scriptWitness.stack = [b'a' * 195] * (2 * NUM_DROPS) + [witness_program]
         child_tx.rehash()
@@ -1199,7 +1199,7 @@ class SegWitTest(BitcoinTestFramework):
         tx = CTransaction()
         tx.vin.append(CTxIn(COutPoint(self.utxo[0].sha256, self.utxo[0].n), b""))
         value = self.utxo[0].nValue
-        for i in range(10):
+        for _ in range(10):
             tx.vout.append(CTxOut(int(value / 10), script_pubkey))
         tx.vout[0].nValue -= 1000
         assert tx.vout[0].nValue >= 0
@@ -1372,7 +1372,7 @@ class SegWitTest(BitcoinTestFramework):
             tx = CTransaction()
             tx.vin.append(CTxIn(COutPoint(self.utxo[0].sha256, self.utxo[0].n), b""))
             split_value = (self.utxo[0].nValue - 4000) // NUM_SEGWIT_VERSIONS
-            for i in range(NUM_SEGWIT_VERSIONS):
+            for _ in range(NUM_SEGWIT_VERSIONS):
                 tx.vout.append(CTxOut(split_value, CScript([OP_TRUE])))
             tx.rehash()
             block = self.build_next_block()
@@ -1646,7 +1646,7 @@ class SegWitTest(BitcoinTestFramework):
         tx = CTransaction()
         tx.vin.append(CTxIn(COutPoint(prev_utxo.sha256, prev_utxo.n), b""))
         split_value = prev_utxo.nValue // NUM_SIGHASH_TESTS
-        for i in range(NUM_SIGHASH_TESTS):
+        for _ in range(NUM_SIGHASH_TESTS):
             tx.vout.append(CTxOut(split_value, script_pubkey))
         tx.wit.vtxinwit.append(CTxInWitness())
         sign_p2pk_witness_input(witness_program, tx, 0, SIGHASH_ALL, prev_utxo.nValue, key)
@@ -1676,7 +1676,7 @@ class SegWitTest(BitcoinTestFramework):
                 tx.wit.vtxinwit.append(CTxInWitness())
                 total_value += temp_utxos[i].nValue
             split_value = total_value // num_outputs
-            for i in range(num_outputs):
+            for _ in range(num_outputs):
                 tx.vout.append(CTxOut(split_value, script_pubkey))
             for i in range(num_inputs):
                 # Now try to sign each input, using a random hashtype.
@@ -1974,7 +1974,7 @@ class SegWitTest(BitcoinTestFramework):
         split_value = self.utxo[0].nValue // outputs
         tx = CTransaction()
         tx.vin.append(CTxIn(COutPoint(self.utxo[0].sha256, self.utxo[0].n), b""))
-        for i in range(outputs):
+        for _ in range(outputs):
             tx.vout.append(CTxOut(split_value, script_pubkey))
         tx.vout[-2].scriptPubKey = script_pubkey_toomany
         tx.vout[-1].scriptPubKey = script_pubkey_justright
@@ -2060,7 +2060,7 @@ class SegWitTest(BitcoinTestFramework):
                 if (len(tx.wit.vtxinwit) != len(tx.vin)):
                     # vtxinwit must have the same length as vin
                     tx.wit.vtxinwit = tx.wit.vtxinwit[:len(tx.vin)]
-                    for i in range(len(tx.wit.vtxinwit), len(tx.vin)):
+                    for _ in range(len(tx.wit.vtxinwit), len(tx.vin)):
                         tx.wit.vtxinwit.append(CTxInWitness())
                 r += tx.wit.serialize()
             r += struct.pack("<I", tx.nLockTime)
diff --git a/test/functional/p2p_sendheaders.py b/test/functional/p2p_sendheaders.py
index 481b1c1841..126a46bd53 100755
--- a/test/functional/p2p_sendheaders.py
+++ b/test/functional/p2p_sendheaders.py
@@ -328,7 +328,7 @@ class SendHeadersTest(BitcoinTestFramework):
             for j in range(2):
                 self.log.debug("Part 2.{}.{}: starting...".format(i, j))
                 blocks = []
-                for b in range(i + 1):
+                for _ in range(i + 1):
                     blocks.append(create_block(tip, create_coinbase(height), block_time))
                     blocks[-1].solve()
                     tip = blocks[-1].sha256
@@ -443,7 +443,7 @@ class SendHeadersTest(BitcoinTestFramework):
 
         # Create 2 blocks.  Send the blocks, then send the headers.
         blocks = []
-        for b in range(2):
+        for _ in range(2):
             blocks.append(create_block(tip, create_coinbase(height), block_time))
             blocks[-1].solve()
             tip = blocks[-1].sha256
@@ -461,7 +461,7 @@ class SendHeadersTest(BitcoinTestFramework):
 
         # This time, direct fetch should work
         blocks = []
-        for b in range(3):
+        for _ in range(3):
             blocks.append(create_block(tip, create_coinbase(height), block_time))
             blocks[-1].solve()
             tip = blocks[-1].sha256
@@ -482,7 +482,7 @@ class SendHeadersTest(BitcoinTestFramework):
         blocks = []
 
         # Create extra blocks for later
-        for b in range(20):
+        for _ in range(20):
             blocks.append(create_block(tip, create_coinbase(height), block_time))
             blocks[-1].solve()
             tip = blocks[-1].sha256
@@ -529,7 +529,7 @@ class SendHeadersTest(BitcoinTestFramework):
             test_node.last_message.pop("getdata", None)
             blocks = []
             # Create two more blocks.
-            for j in range(2):
+            for _ in range(2):
                 blocks.append(create_block(tip, create_coinbase(height), block_time))
                 blocks[-1].solve()
                 tip = blocks[-1].sha256
@@ -550,7 +550,7 @@ class SendHeadersTest(BitcoinTestFramework):
         # Now we test that if we repeatedly don't send connecting headers, we
         # don't go into an infinite loop trying to get them to connect.
         MAX_UNCONNECTING_HEADERS = 10
-        for j in range(MAX_UNCONNECTING_HEADERS + 1):
+        for _ in range(MAX_UNCONNECTING_HEADERS + 1):
             blocks.append(create_block(tip, create_coinbase(height), block_time))
             blocks[-1].solve()
             tip = blocks[-1].sha256
diff --git a/test/functional/p2p_tx_download.py b/test/functional/p2p_tx_download.py
index 2527edc135..3ea1c6e5e7 100755
--- a/test/functional/p2p_tx_download.py
+++ b/test/functional/p2p_tx_download.py
@@ -162,7 +162,7 @@ class TxDownloadTest(BitcoinTestFramework):
         # Setup the p2p connections
         self.peers = []
         for node in self.nodes:
-            for i in range(NUM_INBOUND):
+            for _ in range(NUM_INBOUND):
                 self.peers.append(node.add_p2p_connection(TestP2PConn()))
 
         self.log.info("Nodes are setup with {} incoming connections each".format(NUM_INBOUND))
diff --git a/test/functional/rpc_fundrawtransaction.py b/test/functional/rpc_fundrawtransaction.py
index 57c8f511ac..2a0971b808 100755
--- a/test/functional/rpc_fundrawtransaction.py
+++ b/test/functional/rpc_fundrawtransaction.py
@@ -554,7 +554,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         self.nodes[1].generate(1)
         self.sync_all()
 
-        for i in range(0,20):
+        for _ in range(20):
             self.nodes[0].sendtoaddress(self.nodes[1].getnewaddress(), 0.01)
         self.nodes[0].generate(1)
         self.sync_all()
@@ -582,7 +582,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         self.nodes[1].generate(1)
         self.sync_all()
 
-        for i in range(0,20):
+        for _ in range(20):
             self.nodes[0].sendtoaddress(self.nodes[1].getnewaddress(), 0.01)
         self.nodes[0].generate(1)
         self.sync_all()
diff --git a/test/functional/rpc_generateblock.py b/test/functional/rpc_generateblock.py
index aa58c0af9d..08ff0fba50 100755
--- a/test/functional/rpc_generateblock.py
+++ b/test/functional/rpc_generateblock.py
@@ -55,7 +55,7 @@ class GenerateBlockTest(BitcoinTestFramework):
         node.generatetoaddress(110, address)
 
         # Generate some extra mempool transactions to verify they don't get mined
-        for i in range(10):
+        for _ in range(10):
             node.sendtoaddress(address, 0.001)
 
         self.log.info('Generate block with txid')
diff --git a/test/functional/rpc_psbt.py b/test/functional/rpc_psbt.py
index 4d985dd1b1..f7f23bc8f4 100755
--- a/test/functional/rpc_psbt.py
+++ b/test/functional/rpc_psbt.py
@@ -430,7 +430,7 @@ class PSBTTest(BitcoinTestFramework):
         # Check that joining shuffles the inputs and outputs
         # 10 attempts should be enough to get a shuffled join
         shuffled = False
-        for i in range(0, 10):
+        for _ in range(10):
             shuffled_joined = self.nodes[0].joinpsbts([psbt, psbt2])
             shuffled |= joined != shuffled_joined
             if shuffled:
diff --git a/test/functional/test_framework/messages.py b/test/functional/test_framework/messages.py
index 2462a9a6db..da956a94de 100755
--- a/test/functional/test_framework/messages.py
+++ b/test/functional/test_framework/messages.py
@@ -111,7 +111,7 @@ def deser_uint256(f):
 
 def ser_uint256(u):
     rs = b""
-    for i in range(8):
+    for _ in range(8):
         rs += struct.pack("<I", u & 0xFFFFFFFF)
         u >>= 32
     return rs
@@ -134,7 +134,7 @@ def uint256_from_compact(c):
 def deser_vector(f, c):
     nit = deser_compact_size(f)
     r = []
-    for i in range(nit):
+    for _ in range(nit):
         t = c()
         t.deserialize(f)
         r.append(t)
@@ -157,7 +157,7 @@ def ser_vector(l, ser_function_name=None):
 def deser_uint256_vector(f):
     nit = deser_compact_size(f)
     r = []
-    for i in range(nit):
+    for _ in range(nit):
         t = deser_uint256(f)
         r.append(t)
     return r
@@ -173,7 +173,7 @@ def ser_uint256_vector(l):
 def deser_string_vector(f):
     nit = deser_compact_size(f)
     r = []
-    for i in range(nit):
+    for _ in range(nit):
         t = deser_string(f)
         r.append(t)
     return r
@@ -467,7 +467,7 @@ class CTransaction:
         else:
             self.vout = deser_vector(f, CTxOut)
         if flags != 0:
-            self.wit.vtxinwit = [CTxInWitness() for i in range(len(self.vin))]
+            self.wit.vtxinwit = [CTxInWitness() for _ in range(len(self.vin))]
             self.wit.deserialize(f)
         else:
             self.wit = CTxWitness()
@@ -500,7 +500,7 @@ class CTransaction:
             if (len(self.wit.vtxinwit) != len(self.vin)):
                 # vtxinwit must have the same length as vin
                 self.wit.vtxinwit = self.wit.vtxinwit[:len(self.vin)]
-                for i in range(len(self.wit.vtxinwit), len(self.vin)):
+                for _ in range(len(self.wit.vtxinwit), len(self.vin)):
                     self.wit.vtxinwit.append(CTxInWitness())
             r += self.wit.serialize()
         r += struct.pack("<I", self.nLockTime)
@@ -735,7 +735,7 @@ class P2PHeaderAndShortIDs:
         self.header.deserialize(f)
         self.nonce = struct.unpack("<Q", f.read(8))[0]
         self.shortids_length = deser_compact_size(f)
-        for i in range(self.shortids_length):
+        for _ in range(self.shortids_length):
             # shortids are defined to be 6 bytes in the spec, so append
             # two zero bytes and read it in as an 8-byte number
             self.shortids.append(struct.unpack("<Q", f.read(6) + b'\x00\x00')[0])
@@ -852,7 +852,7 @@ class BlockTransactionsRequest:
     def deserialize(self, f):
         self.blockhash = deser_uint256(f)
         indexes_length = deser_compact_size(f)
-        for i in range(indexes_length):
+        for _ in range(indexes_length):
             self.indexes.append(deser_compact_size(f))
 
     def serialize(self):
diff --git a/test/functional/test_framework/script.py b/test/functional/test_framework/script.py
index cc5f8307d3..5e35ba0fce 100644
--- a/test/functional/test_framework/script.py
+++ b/test/functional/test_framework/script.py
@@ -646,7 +646,7 @@ def LegacySignatureHash(script, txTo, inIdx, hashtype):
 
         tmp = txtmp.vout[outIdx]
         txtmp.vout = []
-        for i in range(outIdx):
+        for _ in range(outIdx):
             txtmp.vout.append(CTxOut(-1))
         txtmp.vout.append(tmp)
 
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
index 506057f1fa..3362b41209 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -529,7 +529,7 @@ def create_confirmed_utxos(fee, node, count):
     addr2 = node.getnewaddress()
     if iterations <= 0:
         return utxos
-    for i in range(iterations):
+    for _ in range(iterations):
         t = utxos.pop()
         inputs = []
         inputs.append({"txid": t["txid"], "vout": t["vout"]})
@@ -556,7 +556,7 @@ def gen_return_txouts():
     # So we have big transactions (and therefore can't fit very many into each block)
     # create one script_pubkey
     script_pubkey = "6a4d0200"  # OP_RETURN OP_PUSH2 512 bytes
-    for i in range(512):
+    for _ in range(512):
         script_pubkey = script_pubkey + "01"
     # concatenate 128 txouts of above script_pubkey which we'll insert before the txout for change
     txouts = []
@@ -564,7 +564,7 @@ def gen_return_txouts():
     txout = CTxOut()
     txout.nValue = 0
     txout.scriptPubKey = hex_str_to_bytes(script_pubkey)
-    for k in range(128):
+    for _ in range(128):
         txouts.append(txout)
     return txouts
 
diff --git a/test/functional/wallet_backup.py b/test/functional/wallet_backup.py
index 9dd91b2495..4766355335 100755
--- a/test/functional/wallet_backup.py
+++ b/test/functional/wallet_backup.py
@@ -129,7 +129,7 @@ class WalletBackupTest(BitcoinTestFramework):
 
         self.log.info("Creating transactions")
         # Five rounds of sending each other transactions.
-        for i in range(5):
+        for _ in range(5):
             self.do_one_round()
 
         self.log.info("Backing up")
@@ -142,7 +142,7 @@ class WalletBackupTest(BitcoinTestFramework):
         self.nodes[2].dumpwallet(os.path.join(self.nodes[2].datadir, 'wallet.dump'))
 
         self.log.info("More transactions")
-        for i in range(5):
+        for _ in range(5):
             self.do_one_round()
 
         # Generate 101 more blocks, so any fees paid mature
diff --git a/test/functional/wallet_basic.py b/test/functional/wallet_basic.py
index 81382d94ad..d9a8b58a84 100755
--- a/test/functional/wallet_basic.py
+++ b/test/functional/wallet_basic.py
@@ -569,7 +569,7 @@ class WalletTest(BitcoinTestFramework):
         # So we should be able to generate exactly chainlimit txs for each original output
         sending_addr = self.nodes[1].getnewaddress()
         txid_list = []
-        for i in range(chainlimit * 2):
+        for _ in range(chainlimit * 2):
             txid_list.append(self.nodes[0].sendtoaddress(sending_addr, Decimal('0.0001')))
         assert_equal(self.nodes[0].getmempoolinfo()['size'], chainlimit * 2)
         assert_equal(len(txid_list), chainlimit * 2)
diff --git a/test/functional/wallet_bumpfee.py b/test/functional/wallet_bumpfee.py
index 72c85b8832..0ef78b0e1c 100755
--- a/test/functional/wallet_bumpfee.py
+++ b/test/functional/wallet_bumpfee.py
@@ -62,7 +62,7 @@ class BumpFeeTest(BitcoinTestFramework):
         self.log.info("Mining blocks...")
         peer_node.generate(110)
         self.sync_all()
-        for i in range(25):
+        for _ in range(25):
             peer_node.sendtoaddress(rbf_node_address, 0.001)
         self.sync_all()
         peer_node.generate(1)
diff --git a/test/functional/wallet_create_tx.py b/test/functional/wallet_create_tx.py
index 330de8b0fc..ed9159726a 100755
--- a/test/functional/wallet_create_tx.py
+++ b/test/functional/wallet_create_tx.py
@@ -45,7 +45,7 @@ class CreateTxWalletTest(BitcoinTestFramework):
 
     def test_tx_size_too_large(self):
         # More than 10kB of outputs, so that we hit -maxtxfee with a high feerate
-        outputs = {self.nodes[0].getnewaddress(address_type='bech32'): 0.000025 for i in range(400)}
+        outputs = {self.nodes[0].getnewaddress(address_type='bech32'): 0.000025 for _ in range(400)}
         raw_tx = self.nodes[0].createrawtransaction(inputs=[], outputs=outputs)
 
         for fee_setting in ['-minrelaytxfee=0.01', '-mintxfee=0.01', '-paytxfee=0.01']:
diff --git a/test/functional/wallet_descriptor.py b/test/functional/wallet_descriptor.py
index 289ccf43ec..9c63e8f7d3 100755
--- a/test/functional/wallet_descriptor.py
+++ b/test/functional/wallet_descriptor.py
@@ -107,7 +107,7 @@ class WalletDescriptorTest(BitcoinTestFramework):
         assert_equal(info2['desc'], info3['desc'])
 
         self.log.info("Test that getnewaddress still works after keypool is exhausted in an encrypted wallet")
-        for i in range(0, 500):
+        for _ in range(500):
             send_wrpc.getnewaddress()
 
         self.log.info("Test that unlock is needed when deriving only hardened keys in an encrypted wallet")
@@ -120,7 +120,7 @@ class WalletDescriptorTest(BitcoinTestFramework):
         }])
         send_wrpc.walletlock()
         # Exhaust keypool of 100
-        for i in range(0, 100):
+        for _ in range(100):
             send_wrpc.getnewaddress(address_type='bech32')
         # This should now error
         assert_raises_rpc_error(-12, "Keypool ran out, please call keypoolrefill first", send_wrpc.getnewaddress, '', 'bech32')
diff --git a/test/functional/wallet_dump.py b/test/functional/wallet_dump.py
index 6bfb468823..06f01ef191 100755
--- a/test/functional/wallet_dump.py
+++ b/test/functional/wallet_dump.py
@@ -116,7 +116,7 @@ class WalletDumpTest(BitcoinTestFramework):
         test_addr_count = 10
         addrs = []
         for address_type in ['legacy', 'p2sh-segwit', 'bech32']:
-            for i in range(0, test_addr_count):
+            for _ in range(test_addr_count):
                 addr = self.nodes[0].getnewaddress(address_type=address_type)
                 vaddr = self.nodes[0].getaddressinfo(addr)  # required to get hd keypath
                 addrs.append(vaddr)
diff --git a/test/functional/wallet_groups.py b/test/functional/wallet_groups.py
index 9dd55b4ab1..b6fe295127 100755
--- a/test/functional/wallet_groups.py
+++ b/test/functional/wallet_groups.py
@@ -27,8 +27,8 @@ class WalletGroupTest(BitcoinTestFramework):
         self.nodes[0].generate(110)
 
         # Get some addresses from the two nodes
-        addr1 = [self.nodes[1].getnewaddress() for i in range(3)]
-        addr2 = [self.nodes[2].getnewaddress() for i in range(3)]
+        addr1 = [self.nodes[1].getnewaddress() for _ in range(3)]
+        addr2 = [self.nodes[2].getnewaddress() for _ in range(3)]
         addrs = addr1 + addr2
 
         # Send 1 + 0.5 coin to each address
@@ -71,7 +71,7 @@ class WalletGroupTest(BitcoinTestFramework):
 
         # Fill node2's wallet with 10000 outputs corresponding to the same
         # scriptPubKey
-        for i in range(5):
+        for _ in range(5):
             raw_tx = self.nodes[0].createrawtransaction([{"txid":"0"*64, "vout":0}], [{addr2[0]: 0.05}])
             tx = FromHex(CTransaction(), raw_tx)
             tx.vin = []
diff --git a/test/functional/wallet_labels.py b/test/functional/wallet_labels.py
index fb4a1f9792..cff59bd1c1 100755
--- a/test/functional/wallet_labels.py
+++ b/test/functional/wallet_labels.py
@@ -118,7 +118,7 @@ class WalletLabelsTest(BitcoinTestFramework):
         if not self.options.descriptors:
             for label in labels:
                 addresses = []
-                for x in range(10):
+                for _ in range(10):
                     addresses.append(node.getnewaddress())
                 multisig_address = node.addmultisigaddress(5, addresses, label.name)['address']
                 label.add_address(multisig_address)
diff --git a/test/functional/wallet_multiwallet.py b/test/functional/wallet_multiwallet.py
index a54396cad3..1872545cdb 100755
--- a/test/functional/wallet_multiwallet.py
+++ b/test/functional/wallet_multiwallet.py
@@ -26,7 +26,7 @@ FEATURE_LATEST = 169900
 got_loading_error = False
 def test_load_unload(node, name):
     global got_loading_error
-    for i in range(10):
+    for _ in range(10):
         if got_loading_error:
             return
         try: