Functional tests

The /test/ (/test/) directory contains integration tests that test bitcoind and its utilities in their entirety. It does not contain unit tests, which can be found in /src/test (/src/test), /src/wallet/test (/src/wallet/test), etc.

There are currently two sets of tests in the /test/ (/test/) directory:

• functional (/test/functional) which test the functionality of bitcoind and bitcoin-qt by interacting with them through the RPC and P2P interfaces.
• util (/test/util) which tests the bitcoin utilities, currently only bitcoin-tx.

The util tests are run as part of make check target. The functional tests are run by the Teamcity continuous build process whenever a diff is created or updated on Phabricator. Both sets of tests can also be run locally.

Running functional tests locally

Build for your system first. Be sure to enable wallet, utils and daemon when you configure. Tests will not run otherwise.

Functional tests

Dependencies

The ZMQ functional test requires a python ZMQ library. To install it:

• On Unix, run sudo apt-get install python3-zmq
• On mac OS, run pip3 install pyzmq

Running the tests

Individual tests can be run through the test_runner harness, eg:

test/functional/test_runner.py example_test

You can run any combination (incl. duplicates) of tests by calling:

test/functional/test_runner.py <testname1> <testname2> <testname3> ...

Run the regression test suite with:

test/functional/test_runner.py

Run all possible tests with

test/functional/test_runner.py --extended

By default, the test_runner will run many tests in parallel. To specify how many jobs to run, append --jobs=n

The individual tests and the test_runner harness have many command-line options. Run test/functional/test_runner.py -h to see them all.

Troubleshooting and debugging test failures

Debug & iterate faster

Don’t wait longer than you need to identify issues. Save yourself time while debugging:

Use –failfast when running many tests

Stop on first test failure:

test/functional/test_runner.py --failfast

Use –timeout-factor when debugging timeouts

Don’t wait for the default timeout (60 seconds) for every failure when debugging an issue you know about. Use –timeout-factor while you iterate on a solution:

test/functional/test_runner.py --timeout-factor=0.3 abc_rpc_isfinal

Use –repeat when debugging intermittent issues

Run a test multiple times in parallel to look for intermittent issues.

test/functional/test_runner.py --repeat 100 p2p_leak

Resource contention

The P2P and RPC ports used by the bitcoind nodes-under-test are chosen to make conflicts with other processes unlikely. However, if there is another bitcoind process running on the system (perhaps from a previous test which hasn’t successfully killed all its bitcoind nodes), then there may be a port conflict which will cause the test to fail. It is recommended that you run the tests on a system where no other bitcoind processes are running.

On linux, the test framework will warn if there is another bitcoind process running when the tests are started.

If there are zombie bitcoind processes after test failure, you can kill them by running the following commands. Note that these commands will kill all bitcoind processes running on the system, so should not be used if any non-test bitcoind processes are being run.

killall bitcoind

or

pkill -9 bitcoind

Data directory cache

A pre-mined blockchain with 200 blocks is generated the first time a functional test is run and is stored in test/cache. This speeds up test startup times since new blockchains don’t need to be generated for each test. However, the cache may get into a bad state, in which case tests will fail. If this happens, remove the cache directory (and make sure bitcoind processes are stopped as above):

rm -rf test/cache
killall bitcoind

Test logging

The tests contain logging at different levels (debug, info, warning, etc). By default:

• When run through the test_runner harness, all logs are written to test_framework.log and no logs are output to the console.
• When run directly, all logs are written to test_framework.log and INFO level and above are output to the console.
• When run by our CI, no logs are output to the console. However, if a test fails, the test_framework.log and bitcoind debug.logs will all be dumped to the console to help troubleshooting.

These log files can be located under the test data directory (which is always printed in the first line of test output):

• <test data directory>/test_framework.log
• <test data directory>/node<node number>/regtest/debug.log.

The node number identifies the relevant test node, starting from node0, which corresponds to its position in the nodes list of the specific test, e.g. self.nodes[0].

To change the level of logs output to the console, use the -l command line argument.

test_framework.log and bitcoind debug.logs can be combined into a single aggregate log by running the combine_logs.py script. The output can be plain text, colorized text or html. For example:

test/functional/combine_logs.py -c <test data directory> | less -r

will pipe the colorized logs from the test into less.

The last failed test data directory can also be accessed via the ./lastfailure symlink to avoid copy-pasting a new directory on each iterated test run.

Use --tracerpc to trace out all the RPC calls and responses to the console. For some tests (eg any that use submitblock to submit a full block over RPC), this can result in a lot of screen output.

By default, the test data directory will be deleted after a successful run. Use --nocleanup to leave the test data directory intact. The test data directory is never deleted after a failed test.

Attaching a debugger

A python debugger can be attached to tests at any point. Just add the line:

import pdb; pdb.set_trace()

anywhere in the test. You will then be able to inspect variables, as well as call methods that interact with the bitcoind nodes-under-test.

If further introspection of the bitcoind instances themselves becomes necessary, this can be accomplished by first setting a pdb breakpoint at an appropriate location, running the test to that point, then using gdb (or lldb on macOS) to attach to the process and debug.

For instance, to attach to self.node[1] during a run you can get the pid of the node within pdb.

(pdb) self.node[1].process.pid

Alternatively, you can find the pid by inspecting the temp folder for the specific test you are running. The path to that folder is printed at the beginning of every test run:

2017-06-27 14:13:56.686000 TestFramework (INFO): Initializing test directory /tmp/user/1000/testo9vsdjo3

Use the path to find the pid file in the temp folder:

cat /tmp/user/1000/testo9vsdjo3/node1/regtest/bitcoind.pid

Then you can use the pid to start gdb:

gdb /home/example/bitcoind <pid>

Note: gdb attach step may require sudo. To get rid of this, you can run:

echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope

Often while debugging rpc calls from functional tests, the test might reach timeout before process can return a response. Use --timeout-factor=0 to disable all rpc timeouts for that particular functional test. Ex: test/functional/test_runner.py wallet_hd --timeout-factor=0.

Benchmarking and profiling with perf

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

See also:

• Installing perf
• Perf examples
• Hotspot: a GUI for perf output analysis

Prevent using deprecated features

Python will issue a DeprecationWarning when a deprecated feature is encountered in a script. By default, this warning message is ignored and not displayed to the user. This behavior can be changed by setting the environment variable PYTHONWARNINGS as follow:

PYTHONWARNINGS=default::DeprecationWarning

The warning message will now be printed to the sys.stderr output.

Util tests

Util tests can be run locally by running test/util/bitcoin-util-test.py. Use the -v option for verbose output.

Writing functional tests

Example test

The file test/functional/example_test.py (/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.

Coverage

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.

Style guidelines

• 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)
• Use type hints in your code to improve code readability and to detect possible bugs earlier.
• Avoid wildcard imports where possible
• 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() and setup_xxxx() methods at the top of the subclass, then locally-defined helper methods, then the run_test() method.

Naming guidelines

• 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, eg feature_rbf.py
  • interface for tests for other interfaces (REST, ZMQ, etc), eg interface_rest.py
  • mempool for tests for mempool behaviour, eg mempool_reorg.py
  • mining for tests for mining features, eg mining_prioritisetransaction.py
  • p2p for tests that explicitly test the p2p interface, eg p2p_disconnect_ban.py
  • rpc for tests for individual RPC methods or features, eg rpc_listtransactions.py
  • tool for tests for tools, eg tool_wallet.py
  • wallet for tests for wallet features, eg wallet_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, not rpc_decode_script.py
• Don’t use the redundant word test in the name, eg interface_zmq.py, not interface_zmq_test.py

General test-writing advice

• 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 in set_test_params() to True to initialize an empty blockchain and start from the Genesis block, rather than load a premined blockchain from cache with the default value of False. The cached data directories contain a 200-block pre-mined blockchain with the spendable mining rewards being split between four nodes. Each node has 25 mature block subsidies (25x50=1250 BTC) in its wallet. Using them is much more efficient than mining blocks in your test.
• 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 and CTransaction 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.

RPC and P2P definitions

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 RPCs
• ProcessMessage() in /src/net_processing.cpp for parsing P2P messages

Using the P2P interface

• P2Ps can be used to test specific P2P protocol behavior. p2p.py (/test/functional/test_framework/p2p.py) contains test framework p2p objects and messages.py (/test/functional/test_framework/messages.py) contains all the definitions for objects passed 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.

P2PConnections can be used as such:

p2p_conn = node.add_p2p_connection(P2PInterface())
p2p_conn.send_and_ping(msg)

They can also be referenced by indexing into a TestNode’s p2ps list, which contains the list of test framework p2p objects connected to itself (it does not include any TestNodes):

node.p2ps[0].sync_with_ping()

More examples can be found in p2p_unrequested_blocks.py (/test/functional/p2p_unrequested_blocks.py), p2p_compactblocks.py (/test/functional/p2p_compactblocks.py).

Prototyping tests

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.

Test framework modules

The following are useful modules for test developers. They are located in test/functional/test_framework/ (/test/functional/test_framework).

authproxy.py (/test/functional/test_framework/authproxy.py)

Taken from the python-bitcoinrpc repository.

test_framework.py (/test/functional/test_framework/test_framework.py)

Base class for functional tests.

util.py (/test/functional/test_framework/util.py)

Generally useful functions.

p2p.py (/test/functional/test_framework/p2p.py)

Test objects for interacting with a bitcoind node over the p2p interface.

script.py (/test/functional/test_framework/script.py)

Utilities for manipulating transaction scripts (originally from python-bitcoinlib)

key.py (/test/functional/test_framework/key.py)

Test-only secp256k1 elliptic curve implementation

blocktools.py (/test/functional/test_framework/blocktools.py)

Helper functions for creating blocks and transactions.