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Functional tests

The /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/wallet/test, etc.

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

  • functional which test the functionality of bitcoind and bitcoin-qt by interacting with them through the RPC and P2P interfaces.
  • 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


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 by directly calling the test script, eg:


or can be run through the test_runner harness, eg:

test/functional/ example_test

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

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

Run the regression test suite with:


Run all possible tests with

test/functional/ --extended

By default, up to 4 tests will be run in parallel by test_runner. To specify how many jobs to run, append --jobs=n

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

Troubleshooting and debugging test failures

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


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 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 on Travis, 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.

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 script. The output can be plain text, colorized text or html. For example: -c <test data directory> | less -r

will pipe the colorized logs from the test into less.

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 to attach to the process and debug.

For instance, to attach to self.node[1] during a run:

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

use the directory path to get the pid from the pid file:

cat /tmp/user/1000/testo9vsdjo3/node1/regtest/
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
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:


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

Util tests

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

Writing functional tests

Example test

The 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 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)
  • 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 BitcoinTestFramwork, 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>_<subject>.py, where <area> can be one of the following:
    • feature for tests for full features that aren't wallet/mining/mempool, eg
    • interface for tests for other interfaces (REST, ZMQ, etc), eg
    • mempool for tests for mempool behaviour, eg
    • mining for tests for mining features, eg
    • p2p for tests that explicitly test the p2p interface, eg
    • rpc for tests for individual RPC methods or features, eg
    • wallet for tests for wallet features, eg
  • 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, not
  • Don't use the redundant word test in the name, eg, not

General test-writing advice

  • 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 or on Travis).
  • 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 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 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

  • 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. Example tests are,

test-framework modules


Taken from the python-bitcoinrpc repository.


Base class for functional tests.


Generally useful functions.


Basic code to support P2P connectivity to a bitcoind.


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


Wrapper around OpenSSL EC_Key (originally from python-bitcoinlib)


Helpers for


Helper functions for creating blocks and transactions.

Running functional tests in an emulator

Cross-compiled binaries can be tested with qemu or wine.



sudo apt install qemu-user-static

In your build directory, run:

cmake -GNinja .. \
   -DCMAKE_TOOLCHAIN_FILE=../cmake/platforms/LinuxAArch64.cmake \
   -DCMAKE_CROSSCOMPILING_EMULATOR=$(command -v qemu-aarch64-static) \

To run functional tests:

QEMU_LD_PREFIX=/usr/aarch64-linux-gnu ninja check-functional