This commit fixes the module-level docstrings for the tests and helper
modules in qa. Many of these tests were uncommented previously - this
commit ensures that every test case has at least a minimum level of
commenting.
In my ever-growing list of test failures, I was seeing this one intermittently.
```
Running 2nd level testscript pruning.py...
Initializing test directory /tmp/testY5ypCv
Warning! This test requires 4GB of disk space and takes over 30 mins (up to 2 hours)
Mining a big blockchain of 995 blocks
Check that we haven't started pruning yet because we're below PruneAfterHeight
Success
Though we're already using more than 550MB, current usage: 587
Mining 25 more blocks should cause the first block file to be pruned
Assertion failed: blk00000.dat not pruned when it should be
File "/home/error/bitcoinxt-0.11D/qa/rpc-tests/test_framework/test_framework.py", line 118, in main
self.run_test()
File "/home/error/bitcoinxt-0.11D/qa/rpc-tests/pruning.py", line 272, in run_test
self.test_height_min()
File "/home/error/bitcoinxt-0.11D/qa/rpc-tests/pruning.py", line 94, in test_height_min
raise AssertionError("blk00000.dat not pruned when it should be")
Stopping nodes
Failed
```
After digging into the test, I found that the code is waiting 10 seconds for blk00000.dat to be deleted, and then throwing this failure if it still exists after 10 seconds.
I increased this amount, had the script print the actual time taken, and ran the test a few more times. The time taken ranged between 8 to 12 seconds. So, I feel that this timeout is too short.
After changing the timeout to 30 seconds, the test passes consistently.
(cherry picked from commit 3469911c89a48dd2fefe4d1c2a0c176256e14ee0)
This adds a -prune=N option to bitcoind, which if set to N>0 will enable block
file pruning. When pruning is enabled, block and undo files will be deleted to
try to keep total space used by those files to below the prune target (N, in
MB) specified by the user, subject to some constraints:
- The last 288 blocks on the main chain are always kept (MIN_BLOCKS_TO_KEEP),
- N must be at least 550MB (chosen as a value for the target that could
reasonably be met, with some assumptions about block sizes, orphan rates,
etc; see comment in main.h),
- No blocks are pruned until chainActive is at least 100,000 blocks long (on
mainnet; defined separately for mainnet, testnet, and regtest in chainparams
as nPruneAfterHeight).
This unsets NODE_NETWORK if pruning is enabled.
Also included is an RPC test for pruning (pruning.py).
Thanks to @rdponticelli for earlier work on this feature; this is based in
part off that work.
