No longer create a default wallet. The default wallet will still be
loaded if it exists and not other wallets were specified (anywhere,
including settings.json, bitcoin.conf, and command line).
Tests are updated to be started with -wallet= if they need the default
wallet.
Added test to wallet_startup.py testing that no default wallet is
created and that it is loaded if it exists and no other wallets were
specified.
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
approaches part of #16613 ("Functional test suite bottlenecks")
The majority of the test time is spent in sync_mempools() after sending to
addresses, i.e. the bottleneck is in relaying transactions. By whitelisting the
peers via -whitelist, the inventory is transmissioned immediately rather than
on average every 5 seconds, speeding up the test by at least a factor of two:
before:
$ time ./wallet_backup.py
real 2m2.523s
user 0m6.093s
sys 0m2.454s
with this PR:
$ time ./wallet_backup_with_whitelist.py
real 0m36.570s
user 0m5.365s
sys 0m1.696s
Note that the test is not deterministic (the sendtoaddress RPC in function
one_send() is executed with a probability of 50%), hence the times could vary
between individual runs.