The 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.
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.
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-accept-block.py, p2p-compactblocks.py.
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