dash/test/functional/README.md
Wladimir J. van der Laan 7be2b2456a Merge #13281: test: Move linters to test/lint, add readme
fa3c910bfeab00703c947c5200a64c21225b50ef test: Move linters to test/lint, add readme (MarcoFalke)

Pull request description:

  This moves the checks and linters from `devtools` to a subfolder in `test`. (Motivated by my opinion that the dev tools are mostly for generating code and updating the repo whereas the linters are read-only checks.)

  Also, adds a readme to clarify that checks and linters are only meant to prevent bugs and user facing issues, not merely stylistic preference or inconsistencies. (This is motivated by the diversity in developers and work flows as well as existing code styles. It would be too disruptive to change all existing code to a single style or too burdensome to force all developers to adhere to a single style. Also note that our style guide is changing, so locking in at the wrong style "too early" would only waste resources.)

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2020-07-29 10:59:04 -05:00

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# Functional tests
### Writing Functional Tests
#### Example test
The [example_test.py](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_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](https://www.python.org/dev/peps/pep-0008/)
- Use a python linter like flake8 before submitting PRs to catch common style
nits (eg trailing whitespace, unused imports, etc)
- See [the python lint script](/test/lint/lint-python.sh) that checks for violations that
could lead to bugs and issues in the test code.
- 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.
- Use `'{}'.format(x)` for string formatting, not `'%s' % x`.
#### 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`
- `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
- 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 (25x500=12500 DASH) 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.
#### 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
- `mininode.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 dashd(s) being tested (using python's asyncore package); the other
implements the test logic.
- `P2PConnection` is the class used to connect to a dashd. `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.
- Call `network_thread_start()` after all `P2PInterface` objects are created to
start the networking thread. (Continue with the test logic in your existing
thread.)
- Can be used to write tests where specific P2P protocol behavior is tested.
Examples tests are `p2p_unrequested_blocks.py`, `p2p_compactblocks.py`.
### test-framework modules
#### [test_framework/authproxy.py](test_framework/authproxy.py)
Taken from the [python-bitcoinrpc repository](https://github.com/jgarzik/python-bitcoinrpc).
#### [test_framework/test_framework.py](test_framework/test_framework.py)
Base class for functional tests.
#### [test_framework/util.py](test_framework/util.py)
Generally useful functions.
#### [test_framework/mininode.py](test_framework/mininode.py)
Basic code to support P2P connectivity to a dashd.
#### [test_framework/script.py](test_framework/script.py)
Utilities for manipulating transaction scripts (originally from python-bitcoinlib)
#### [test_framework/key.py](test_framework/key.py)
Wrapper around OpenSSL EC_Key (originally from python-bitcoinlib)
#### [test_framework/bignum.py](test_framework/bignum.py)
Helpers for script.py
#### [test_framework/blocktools.py](test_framework/blocktools.py)
Helper functions for creating blocks and transactions.