The file test/functional/example_test.py is a heavily commented example of a test case that uses both the RPC and P2P interfaces. If you are writing your first test, copy that file and modify to fit your needs.
Running test/functional/test_runner.py
with the --coverage
argument tracks which RPCs are
called by the tests and prints a report of uncovered RPCs in the summary. This
can be used (along with the --extended
argument) to find out which RPCs we
don't have test cases for.
- Where possible, try to adhere to PEP-8 guidelines
- Use a python linter like flake8 before submitting PRs to catch common style nits (eg trailing whitespace, unused imports, etc)
- The oldest supported Python version is specified in doc/dependencies.md. Consider using pyenv, which checks .python-version, to prevent accidentally introducing modern syntax from an unsupported Python version. The Travis linter also checks this, but possibly not in all cases.
- See the python lint script that checks for violations that could lead to bugs and issues in the test code.
- Use type hints in your code to improve code readability and to detect possible bugs earlier.
- Avoid wildcard imports
- Use a module-level docstring to describe what the test is testing, and how it is testing it.
- When subclassing the BitcoinTestFramework, place overrides for the
set_test_params()
,add_options()
andsetup_xxxx()
methods at the top of the subclass, then locally-defined helper methods, then therun_test()
method. - Use
'{}'.format(x)
for string formatting, not'%s' % x
.
- Name the test
<area>_test.py
, where area can be one of the following:feature
for tests for full features that aren't wallet/mining/mempool, egfeature_rbf.py
interface
for tests for other interfaces (REST, ZMQ, etc), eginterface_rest.py
mempool
for tests for mempool behaviour, egmempool_reorg.py
mining
for tests for mining features, egmining_prioritisetransaction.py
p2p
for tests that explicitly test the p2p interface, egp2p_disconnect_ban.py
rpc
for tests for individual RPC methods or features, egrpc_listtransactions.py
tool
for tests for tools, egtool_wallet.py
wallet
for tests for wallet features, egwallet_keypool.py
- Use an underscore to separate words
- exception: for tests for specific RPCs or command line options which don't include underscores, name the test after the exact RPC or argument name, eg
rpc_decodescript.py
, notrpc_decode_script.py
- exception: for tests for specific RPCs or command line options which don't include underscores, name the test after the exact RPC or argument name, eg
- Don't use the redundant word
test
in the name, eginterface_zmq.py
, notinterface_zmq_test.py
- Instead of inline comments or no test documentation at all, log the comments to the test log, e.g.
self.log.info('Create enough transactions to fill a block')
. Logs make the test code easier to read and the test logic easier to debug. - Set
self.num_nodes
to the minimum number of nodes necessary for the test. Having additional unrequired nodes adds to the execution time of the test as well as memory/CPU/disk requirements (which is important when running tests in parallel). - Avoid stop-starting the nodes multiple times during the test if possible. A stop-start takes several seconds, so doing it several times blows up the runtime of the test.
- Set the
self.setup_clean_chain
variable inset_test_params()
to control whether or not to use the cached data directories. The cached data directories contain a 200-block pre-mined blockchain and wallets for four nodes. Each node has 25 mature blocks (25x50=1250 BTC) in its wallet. - When calling RPCs with lots of arguments, consider using named keyword arguments instead of positional arguments to make the intent of the call clear to readers.
- Many of the core test framework classes such as
CBlock
andCTransaction
don't allow new attributes to be added to their objects at runtime like typical Python objects allow. This helps prevent unpredictable side effects from typographical errors or usage of the objects outside of their intended purpose.
Test writers may find it helpful to refer to the definitions for the RPC and P2P messages. These can be found in the following source files:
/src/rpc/*
for RPCs/src/wallet/rpc*
for wallet RPCsProcessMessage()
in/src/net_processing.cpp
for parsing P2P messages
-
messages.py contains all the definitions for objects that pass over the network (
CBlock
,CTransaction
, etc, along with the network-level wrappers for them,msg_block
,msg_tx
, etc). -
P2P tests have two threads. One thread handles all network communication with the bitcoind(s) being tested in a callback-based event loop; the other implements the test logic.
-
P2PConnection
is the class used to connect to a bitcoind.P2PInterface
contains the higher level logic for processing P2P payloads and connecting to the Bitcoin Core node application logic. For custom behaviour, subclass the P2PInterface object and override the callback methods. -
Can be used to write tests where specific P2P protocol behavior is tested. Examples tests are p2p_unrequested_blocks.py, p2p_compactblocks.py.
The TestShell
class exposes the BitcoinTestFramework
functionality to interactive Python3 environments and can be used to prototype
tests. This may be especially useful in a REPL environment with session logging
utilities, such as
IPython.
The logs of such interactive sessions can later be adapted into permanent test
cases.
The following are useful modules for test developers. They are located in test/functional/test_framework/.
Taken from the python-bitcoinrpc repository.
Base class for functional tests.
Generally useful functions.
Test objects for interacting with a bitcoind node over the p2p interface.
Utilities for manipulating transaction scripts (originally from python-bitcoinlib)
Test-only secp256k1 elliptic curve implementation
Helper functions for creating blocks and transactions.
An easy way to profile node performance during functional tests is provided
for Linux platforms using perf
.
Perf will sample the running node and will generate profile data in the node's
datadir. The profile data can then be presented using perf report
or a graphical
tool like hotspot.
There are two ways of invoking perf: one is to use the --perf
flag when
running tests, which will profile each node during the entire test run: perf
begins to profile when the node starts and ends when it shuts down. The other
way is the use the profile_with_perf
context manager, e.g.
with node.profile_with_perf("send-big-msgs"):
# Perform activity on the node you're interested in profiling, e.g.:
for _ in range(10000):
node.p2p.send_message(some_large_message)
To see useful textual output, run
perf report -i /path/to/datadir/send-big-msgs.perf.data.xxxx --stdio | c++filt | less
- Installing perf
- Perf examples
- Hotspot: a GUI for perf output analysis