Fixes a couple of bugs from the introduction of TestNode:
- test scripts were no longer able to specify a custom timeout for
starting a node. Therefore tests with nodes that take a long time to
start up (eg pruning.py) would fail.
- the test for whether a node has failed on start up was broken
by changing 'assert x is None' to 'assert not x'. Since
subprocess.poll() can return None (indicating the node is still running)
or 0 (indicating the node exited with return code 0), this was a
regression.
This commit moves functions start_node, start_nodes, stop_node and
stop_nodes functions into the BitcoinTestFramework class. It also moves
the bitcoind_processes dict and coverage variables into BitcoinTestFramework.
Adds new functional test, dbcrash.py, which uses -dbcrashratio to exercise the
logic for recovering from a crash during chainstate flush.
dbcrash.py is added to the extended tests, as it may take ~10 minutes to run
Use _Exit() instead of exit() for crash simulation
This eliminates stderr output such as:
terminate called without an active exception
or
Assertion failed: (!pthread_mutex_destroy(&m)), function ~recursive_mutex, file /usr/local/include/boost/thread/pthread/recursive_mutex.hpp, line 104.
Eliminating the stderr output on crash simulation allows testing with
test_runner.py, which reports a test as failed if stderr is produced.
