message: test: Add log messages to test/functional/tool_wallet.py
  and update code comments as per Python PEP 8 style guide.
diff: #!/usr/bin/env python3
  -# Copyright (c) 2018 The Bitcoin Core developers
  +# Copyright (c) 2018-2019 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 bitcoin-wallet."""
  +
  import subprocess
  import textwrap
  @@ -37,18 +38,18 @@ class ToolWalletTest(BitcoinTestFramework):
  assert_equal(stdout, output)
  def run_test(self):
  -
  + self.log.info('Testing that various invalid commands raise with specific error messages')
  self.assert_raises_tool_error('Invalid command: foo', 'foo')
  - # `bitcoin-wallet help` is an error. Use `bitcoin-wallet -help`
  + # `bitcoin-wallet help` raises an error. Use `bitcoin-wallet -help`.
  self.assert_raises_tool_error('Invalid command: help', 'help')
  self.assert_raises_tool_error('Error: two methods provided (info and create). Only one method should be provided.', 'info', 'create')
  self.assert_raises_tool_error('Error parsing command line arguments: Invalid parameter -foo', '-foo')
  self.assert_raises_tool_error('Error loading wallet.dat. Is wallet being used by other process?', '-wallet=wallet.dat', 'info')
  self.assert_raises_tool_error('Error: no wallet file at nonexistent.dat', '-wallet=nonexistent.dat', 'info')
  - # stop the node to close the wallet to call info command
  + # Stop the node to close the wallet to call the info command.
  self.stop_node(0)
  -
  + self.log.info('Calling wallet tool info, testing output')
  out = textwrap.dedent('''\
  Wallet info
  ===========
  @@ -60,11 +61,13 @@ class ToolWalletTest(BitcoinTestFramework):
  ''')
  self.assert_tool_output(out, '-wallet=wallet.dat', 'info')
  - # mutate the wallet to check the info command output changes accordingly
  + # Mutate wallet to verify info command output changes accordingly.
  self.start_node(0)
  + self.log.info('Generating transaction to mutate wallet')
  self.nodes[0].generate(1)
  self.stop_node(0)
  + self.log.info('Calling wallet tool info after generating a transaction, testing output')
  out = textwrap.dedent('''\
  Wallet info
  ===========
  @@ -76,6 +79,7 @@ class ToolWalletTest(BitcoinTestFramework):
  ''')
  self.assert_tool_output(out, '-wallet=wallet.dat', 'info')
  + self.log.info('Calling wallet tool create on an existing wallet, testing output')
  out = textwrap.dedent('''\
  Topping up keypool...
  Wallet info
  @@ -88,7 +92,10 @@ class ToolWalletTest(BitcoinTestFramework):
  ''')
  self.assert_tool_output(out, '-wallet=foo', 'create')
  + self.log.info('Starting node with arg -wallet=foo')
  self.start_node(0, ['-wallet=foo'])
  +
  + self.log.info('Calling getwalletinfo on a different wallet ("foo"), testing output')
  out = self.nodes[0].getwalletinfo()
  self.stop_node(0)
  