dash/test/functional/README.md
MarcoFalke 40420195be
Merge #19804: test/refactor: reference p2p objects explicitly and remove confusing Test_Node.p2p property
10d61505fe77880d6989115defa5e08417f3de2d [test] remove confusing p2p property (gzhao408)
549d30faf04612d9589c81edf9770c99e3221885 scripted-diff: replace p2p with p2ps[0] in p2p_invalid_tx (gzhao408)
7a0de46aeafb351cffa3410e1aae9809fd4698ad [doc] sample code for test framework p2p objects (gzhao408)
784f757994c1306bb6584b14c0c78617d6248432 [refactor] clarify tests by referencing p2p objects directly (gzhao408)

Pull request description:

  The `TestNode` has a `p2p` property which is an alias for `p2ps[0]`.

  I think this should be removed because it can be confusing and misleading (to both the test writer and reviewer), especially if a TestNode has multiple p2ps connected (which is the case for many tests).
  Another example is when a test has multiple subtests that connect 1 p2p and use the `p2p` property to reference it. If the subtests don't completely clean up after themselves, the subtests may affect one another.

  The best way to refer to a connected p2p is use the object returned by `add_p2p_connection` like this:
  ```py
  p2p_conn = node.add_p2p_connection(P2PInterface())
  ```
  A good example is [p2p_invalid_locator.py](https://github.com/bitcoin/bitcoin/blob/master/test/functional/p2p_invalid_locator.py), which cleans up after itself (waits in both `wait_for_disconnect` and in `disconnect_p2ps`) but wouldn't need so much complexity if it just referenced the connections directly.

  If there is only one connected, it's not really that tedious to just use `node.p2ps[0]` instead of `node.p2p` (and it can always be aliased inside the test itself).

ACKs for top commit:
  robot-dreams:
    utACK 10d61505fe77880d6989115defa5e08417f3de2d
  jnewbery:
    utACK 10d61505fe77880d6989115defa5e08417f3de2d
  guggero:
    Concept ACK 10d61505.

Tree-SHA512: 5965548929794ec660dae03467640cb2156d7d826cefd26d3a126472cbc2494b855c1d26bbb7b412281fbdc92b9798b9765a85c27bc1a97f7798f27f64db6f13
2024-01-27 22:55:29 -06:00

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Markdown

# Functional tests
### Writing Functional Tests
#### Example test
The file [test/functional/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/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](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.
- Use [type hints](https://docs.python.org/3/library/typing.html) 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()` and `setup_xxxx()` methods at the top of
the subclass, then locally-defined helper methods, then the `run_test()` method.
- Use `f'{x}'` for string formatting in preference to `'{}'.format(x)` or `'%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`
- `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](/test/README.md#test-logging).
- 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 (25x500=12500 DASH) 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
- `P2P`s can be used to test specific P2P protocol behavior.
[p2p.py](test_framework/p2p.py) contains test framework p2p objects and
[messages.py](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 dashd(s) being tested in a callback-based event loop; 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.
`P2PConnection`s can be used as such:
```python
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 `TestNode`s):
```python
node.p2ps[0].sync_with_ping()
```
More examples can be found in [p2p_unrequested_blocks.py](p2p_unrequested_blocks.py),
[p2p_compactblocks.py](p2p_compactblocks.py).
#### Prototyping tests
The [`TestShell`](test-shell.md) 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](https://ipython.readthedocs.io/en/stable/interactive/reference.html#session-logging-and-restoring).
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_framework).
#### [authproxy.py](test_framework/authproxy.py)
Taken from the [python-bitcoinrpc repository](https://github.com/jgarzik/python-bitcoinrpc).
#### [test_framework.py](test_framework/test_framework.py)
Base class for functional tests.
#### [util.py](test_framework/util.py)
Generally useful functions.
#### [p2p.py](test_framework/p2p.py)
Test objects for interacting with a dashd node over the p2p interface.
#### [script.py](test_framework/script.py)
Utilities for manipulating transaction scripts (originally from python-bitcoinlib)
#### [key.py](test_framework/key.py)
Test-only secp256k1 elliptic curve implementation
#### [blocktools.py](test_framework/blocktools.py)
Helper functions for creating blocks and transactions.
### Benchmarking 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](https://github.com/KDAB/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.
```python
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.p2ps[0].send_message(some_large_message)
```
To see useful textual output, run
```sh
perf report -i /path/to/datadir/send-big-msgs.perf.data.xxxx --stdio | c++filt | less
```
#### See also:
- [Installing perf](https://askubuntu.com/q/50145)
- [Perf examples](http://www.brendangregg.com/perf.html)
- [Hotspot](https://github.com/KDAB/hotspot): a GUI for perf output analysis