text: #!/usr/bin/env python2
  # Copyright (c) 2014-2015 The Bitcoin Core developers
  # Distributed under the MIT software license, see the accompanying
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #
  # Test fee estimation code
  #
  
  from test_framework.test_framework import BitcoinTestFramework
  from test_framework.util import *
  
  # Construct 2 trivial P2SH's and the ScriptSigs that spend them
  # So we can create many many transactions without needing to spend
  # time signing.
  P2SH_1 = "2MySexEGVzZpRgNQ1JdjdP5bRETznm3roQ2" # P2SH of "OP_1 OP_DROP"
  P2SH_2 = "2NBdpwq8Aoo1EEKEXPNrKvr5xQr3M9UfcZA" # P2SH of "OP_2 OP_DROP"
  # Associated ScriptSig's to spend satisfy P2SH_1 and P2SH_2
  # 4 bytes of OP_TRUE and push 2-byte redeem script of "OP_1 OP_DROP" or "OP_2 OP_DROP"
  SCRIPT_SIG = ["0451025175", "0451025275"]
  
  def small_txpuzzle_randfee(from_node, conflist, unconflist, amount, min_fee, fee_increment):
      '''
      Create and send a transaction with a random fee.
      The transaction pays to a trival P2SH script, and assumes that its inputs
      are of the same form.
      The function takes a list of confirmed outputs and unconfirmed outputs
      and attempts to use the confirmed list first for its inputs.
      It adds the newly created outputs to the unconfirmed list.
      Returns (raw transaction, fee)
      '''
      # It's best to exponentially distribute our random fees
      # because the buckets are exponentially spaced.
      # Exponentially distributed from 1-128 * fee_increment
      rand_fee = float(fee_increment)*(1.1892**random.randint(0,28))
      # Total fee ranges from min_fee to min_fee + 127*fee_increment
      fee = min_fee - fee_increment + satoshi_round(rand_fee)
      inputs = []
      total_in = Decimal("0.00000000")
      while total_in <= (amount + fee) and len(conflist) > 0:
          t = conflist.pop(0)
          total_in += t["amount"]
          inputs.append({ "txid" : t["txid"], "vout" : t["vout"]} )
      if total_in <= amount + fee:
          while total_in <= (amount + fee) and len(unconflist) > 0:
              t = unconflist.pop(0)
              total_in += t["amount"]
              inputs.append({ "txid" : t["txid"], "vout" : t["vout"]} )
          if total_in <= amount + fee:
              raise RuntimeError("Insufficient funds: need %d, have %d"%(amount+fee, total_in))
      outputs = {}
      outputs[P2SH_1] = total_in - amount - fee
      outputs[P2SH_2] = amount
      rawtx = from_node.createrawtransaction(inputs, outputs)
      # Createrawtransaction constructions a transaction that is ready to be signed
      # These transactions don't need to be signed, but we still have to insert the ScriptSig
      # that will satisfy the ScriptPubKey.
      completetx = rawtx[0:10]
      inputnum = 0
      for inp in inputs:
          completetx += rawtx[10+82*inputnum:82+82*inputnum]
          completetx += SCRIPT_SIG[inp["vout"]]
          completetx += rawtx[84+82*inputnum:92+82*inputnum]
          inputnum += 1
      completetx += rawtx[10+82*inputnum:]
      txid = from_node.sendrawtransaction(completetx, True)
      unconflist.append({ "txid" : txid, "vout" : 0 , "amount" : total_in - amount - fee})
      unconflist.append({ "txid" : txid, "vout" : 1 , "amount" : amount})
  
      return (completetx, fee)
  
  def split_inputs(from_node, txins, txouts, initial_split = False):
      '''
      We need to generate a lot of very small inputs so we can generate a ton of transactions
      and they will have low priority.
      This function takes an input from txins, and creates and sends a transaction
      which splits the value into 2 outputs which are appended to txouts.
      '''
      prevtxout = txins.pop()
      inputs = []
      outputs = {}
      inputs.append({ "txid" : prevtxout["txid"], "vout" : prevtxout["vout"] })
      half_change = satoshi_round(prevtxout["amount"]/2)
      rem_change = prevtxout["amount"] - half_change  - Decimal("0.00001000")
      outputs[P2SH_1] = half_change
      outputs[P2SH_2] = rem_change
      rawtx = from_node.createrawtransaction(inputs, outputs)
      # If this is the initial split we actually need to sign the transaction
      # Otherwise we just need to insert the property ScriptSig
      if (initial_split) :
          completetx = from_node.signrawtransaction(rawtx)["hex"]
      else :
          completetx = rawtx[0:82] + SCRIPT_SIG[prevtxout["vout"]] + rawtx[84:]
      txid = from_node.sendrawtransaction(completetx, True)
      txouts.append({ "txid" : txid, "vout" : 0 , "amount" : half_change})
      txouts.append({ "txid" : txid, "vout" : 1 , "amount" : rem_change})
  
  def check_estimates(node, fees_seen, max_invalid, print_estimates = True):
      '''
      This function calls estimatefee and verifies that the estimates
      meet certain invariants.
      '''
      all_estimates = [ node.estimatefee(i) for i in range(1,26) ]
      if print_estimates:
          print([str(all_estimates[e-1]) for e in [1,2,3,6,15,25]])
      delta = 1.0e-6 # account for rounding error
      last_e = max(fees_seen)
      for e in [x for x in all_estimates if x >= 0]:
          # Estimates should be within the bounds of what transactions fees actually were:
          if float(e)+delta < min(fees_seen) or float(e)-delta > max(fees_seen):
              raise AssertionError("Estimated fee (%f) out of range (%f,%f)"
                                   %(float(e), min(fees_seen), max(fees_seen)))
          # Estimates should be monotonically decreasing
          if float(e)-delta > last_e:
              raise AssertionError("Estimated fee (%f) larger than last fee (%f) for lower number of confirms"
                                   %(float(e),float(last_e)))
          last_e = e
      valid_estimate = False
      invalid_estimates = 0
      for i,e in enumerate(all_estimates): # estimate is for i+1
          if e >= 0:
              valid_estimate = True
              # estimatesmartfee should return the same result
              assert_equal(node.estimatesmartfee(i+1)["feerate"], e)
  
          else:
              invalid_estimates += 1
  
              # estimatesmartfee should still be valid
              approx_estimate = node.estimatesmartfee(i+1)["feerate"]
              answer_found = node.estimatesmartfee(i+1)["blocks"]
              assert(approx_estimate > 0)
              assert(answer_found > i+1)
  
              # Once we're at a high enough confirmation count that we can give an estimate
              # We should have estimates for all higher confirmation counts
              if valid_estimate:
                  raise AssertionError("Invalid estimate appears at higher confirm count than valid estimate")
  
      # Check on the expected number of different confirmation counts
      # that we might not have valid estimates for
      if invalid_estimates > max_invalid:
          raise AssertionError("More than (%d) invalid estimates"%(max_invalid))
      return all_estimates
  
  
  class EstimateFeeTest(BitcoinTestFramework):
  
      def setup_network(self):
          '''
          We'll setup the network to have 3 nodes that all mine with different parameters.
          But first we need to use one node to create a lot of small low priority outputs
          which we will use to generate our transactions.
          '''
          self.nodes = []
          # Use node0 to mine blocks for input splitting
          self.nodes.append(start_node(0, self.options.tmpdir, ["-maxorphantx=1000",
                                                                "-relaypriority=0", "-whitelist=127.0.0.1"]))
  
          print("This test is time consuming, please be patient")
          print("Splitting inputs to small size so we can generate low priority tx's")
          self.txouts = []
          self.txouts2 = []
          # Split a coinbase into two transaction puzzle outputs
          split_inputs(self.nodes[0], self.nodes[0].listunspent(0), self.txouts, True)
  
          # Mine
          while (len(self.nodes[0].getrawmempool()) > 0):
              self.nodes[0].generate(1)
  
          # Repeatedly split those 2 outputs, doubling twice for each rep
          # Use txouts to monitor the available utxo, since these won't be tracked in wallet
          reps = 0
          while (reps < 5):
              #Double txouts to txouts2
              while (len(self.txouts)>0):
                  split_inputs(self.nodes[0], self.txouts, self.txouts2)
              while (len(self.nodes[0].getrawmempool()) > 0):
                  self.nodes[0].generate(1)
              #Double txouts2 to txouts
              while (len(self.txouts2)>0):
                  split_inputs(self.nodes[0], self.txouts2, self.txouts)
              while (len(self.nodes[0].getrawmempool()) > 0):
                  self.nodes[0].generate(1)
              reps += 1
          print("Finished splitting")
  
          # Now we can connect the other nodes, didn't want to connect them earlier
          # so the estimates would not be affected by the splitting transactions
          # Node1 mines small blocks but that are bigger than the expected transaction rate,
          # and allows free transactions.
          # NOTE: the CreateNewBlock code starts counting block size at 1,000 bytes,
          # (17k is room enough for 110 or so transactions)
          self.nodes.append(start_node(1, self.options.tmpdir,
                                       ["-blockprioritysize=1500", "-blockmaxsize=17000",
                                        "-maxorphantx=1000", "-relaypriority=0", "-debug=estimatefee"]))
          connect_nodes(self.nodes[1], 0)
  
          # Node2 is a stingy miner, that
          # produces too small blocks (room for only 55 or so transactions)
          node2args = ["-blockprioritysize=0", "-blockmaxsize=8000", "-maxorphantx=1000", "-relaypriority=0"]
  
          self.nodes.append(start_node(2, self.options.tmpdir, node2args))
          connect_nodes(self.nodes[0], 2)
          connect_nodes(self.nodes[2], 1)
  
          self.is_network_split = False
          self.sync_all()
  
      def transact_and_mine(self, numblocks, mining_node):
          min_fee = Decimal("0.00001")
          # We will now mine numblocks blocks generating on average 100 transactions between each block
          # 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):
              random.shuffle(self.confutxo)
              for j 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)
                  tx_kbytes = (len(txhex) // 2) / 1000.0
                  self.fees_per_kb.append(float(fee)/tx_kbytes)
              sync_mempools(self.nodes[0:3],.1)
              mined = mining_node.getblock(mining_node.generate(1)[0],True)["tx"]
              sync_blocks(self.nodes[0:3],.1)
              #update which txouts are confirmed
              newmem = []
              for utx in self.memutxo:
                  if utx["txid"] in mined:
                      self.confutxo.append(utx)
                  else:
                      newmem.append(utx)
              self.memutxo = newmem
  
      def run_test(self):
          self.fees_per_kb = []
          self.memutxo = []
          self.confutxo = self.txouts # Start with the set of confirmed txouts after splitting
          print("Will output estimates for 1/2/3/6/15/25 blocks")
  
          for i in xrange(2):
              print("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])
              check_estimates(self.nodes[1], self.fees_per_kb, 14)
  
              print("Creating transactions and mining them at a block size that is just big enough")
              # Generate transactions while mining 10 more blocks, this time with node1
              # which mines blocks with capacity just above the rate that transactions are being created
              self.transact_and_mine(10, self.nodes[1])
              check_estimates(self.nodes[1], self.fees_per_kb, 2)
  
          # Finish by mining a normal-sized block:
          while len(self.nodes[1].getrawmempool()) > 0:
              self.nodes[1].generate(1)
  
          sync_blocks(self.nodes[0:3],.1)
          print("Final estimates after emptying mempools")
          check_estimates(self.nodes[1], self.fees_per_kb, 2)
  
  if __name__ == '__main__':
      EstimateFeeTest().main()
  