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.

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.

- 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)

- The oldest supported Python version is specified in [doc/dependencies.md](/doc/dependencies.md).

Consider using [pyenv](https://github.com/pyenv/pyenv), which checks [.python-version](/.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](https://github.com/bitcoin/bitcoin/pull/14884#discussion_r239585126).

- 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

- 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`.

- 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`

- 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.

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

- `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 pivxd(s) being tested in a callback-based event loop; the other

implements the test logic.

- `P2PConnection` is the class used to connect to a pivxd. `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`.

Base class for functional tests.

Basic code to support P2P connectivity to a pivxd.