[tests] Update functional tests documentation

1 files changed, 110 insertions, 64 deletions

diff --git a/test/functional/README.md b/test/functional/README.md
index e6c4849702..96fe0becce 100644
--- a/test/functional/README.md
+++ b/test/functional/README.md
@@ -1,108 +1,154 @@
-Regression tests
-================
+# Functional tests
 
-### [test_framework/authproxy.py](test_framework/authproxy.py)
-Taken from the [python-bitcoinrpc repository](https://github.com/jgarzik/python-bitcoinrpc).
+### Writing Functional Tests
 
-### [test_framework/test_framework.py](test_framework/test_framework.py)
-Base class for new regression tests.
+#### Example test
 
-### [test_framework/util.py](test_framework/util.py)
-Generally useful functions.
+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.
 
-### [test_framework/mininode.py](test_framework/mininode.py)
-Basic code to support p2p connectivity to a bitcoind.
+#### Coverage
 
-### [test_framework/comptool.py](test_framework/comptool.py)
-Framework for comparison-tool style, p2p tests.
+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.
 
-### [test_framework/script.py](test_framework/script.py)
-Utilities for manipulating transaction scripts (originally from python-bitcoinlib)
+#### Style guidelines
 
-### [test_framework/blockstore.py](test_framework/blockstore.py)
-Implements disk-backed block and tx storage.
+- 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)
+- 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
+  `__init__()`, and `setup_xxxx()` methods at the top of the subclass, then
+  locally-defined helper methods, then the `run_test()` method.
 
-### [test_framework/key.py](test_framework/key.py)
-Wrapper around OpenSSL EC_Key (originally from python-bitcoinlib)
+#### General test-writing advice
 
-### [test_framework/bignum.py](test_framework/bignum.py)
-Helpers for script.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 `__init__()` 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.
 
-### [test_framework/blocktools.py](test_framework/blocktools.py)
-Helper functions for creating blocks and transactions.
+#### RPC and P2P definitions
 
-P2P test design notes
----------------------
+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:
 
-## Mininode
+- `/src/rpc/*` for RPCs
+- `/src/wallet/rpc*` for wallet RPCs
+- `ProcessMessage()` in `/src/net_processing.cpp` for parsing P2P messages
 
-* ```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).
+#### Using the P2P interface
 
-* P2P tests have two threads.  One thread handles all network communication
+- `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 bitcoind(s) being tested (using python's asyncore package); the other
 implements the test logic.
 
-* ```NodeConn``` is the class used to connect to a bitcoind.  If you implement
-a callback class that derives from ```NodeConnCB``` and pass that to the
-```NodeConn``` object, your code will receive the appropriate callbacks when
+- `NodeConn` is the class used to connect to a bitcoind.  If you implement
+a callback class that derives from `NodeConnCB` and pass that to the
+`NodeConn` object, your code will receive the appropriate callbacks when
 events of interest arrive.
 
-* You can pass the same handler to multiple ```NodeConn```'s if you like, or pass
-different ones to each -- whatever makes the most sense for your test.
-
-* Call ```NetworkThread.start()``` after all ```NodeConn``` objects are created to
+- Call `NetworkThread.start()` after all `NodeConn` objects are created to
 start the networking thread.  (Continue with the test logic in your existing
 thread.)
 
-* RPC calls are available in p2p tests.
+- Can be used to write tests where specific P2P protocol behavior is tested.
+Examples tests are `p2p-accept-block.py`, `p2p-compactblocks.py`.
 
-* Can be used to write free-form tests, where specific p2p-protocol behavior
-is tested.  Examples: ```p2p-accept-block.py```, ```p2p-compactblocks.py```.
+#### Comptool
 
-## Comptool
+- Comptool is a Testing framework for writing tests that compare the block/tx acceptance
+behavior of a bitcoind against 1 or more other bitcoind instances. It should not be used
+to write static tests with known outcomes, since that type of test is easier to write and
+maintain using the standard BitcoinTestFramework.
 
-* Testing framework for writing tests that compare the block/tx acceptance
-behavior of a bitcoind against 1 or more other bitcoind instances, or against
-known outcomes, or both.
-
-* Set the ```num_nodes``` variable (defined in ```ComparisonTestFramework```) to start up
-1 or more nodes.  If using 1 node, then ```--testbinary``` can be used as a command line
+- Set the `num_nodes` variable (defined in `ComparisonTestFramework`) to start up
+1 or more nodes.  If using 1 node, then `--testbinary` can be used as a command line
 option to change the bitcoind binary used by the test.  If using 2 or more nodes,
-then ```--refbinary``` can be optionally used to change the bitcoind that will be used
+then `--refbinary` can be optionally used to change the bitcoind that will be used
 on nodes 2 and up.
 
-* Implement a (generator) function called ```get_tests()``` which yields ```TestInstance```s.
-Each ```TestInstance``` consists of:
-  - a list of ```[object, outcome, hash]``` entries
-    * ```object``` is a ```CBlock```, ```CTransaction```, or
-    ```CBlockHeader```.  ```CBlock```'s and ```CTransaction```'s are tested for
-    acceptance.  ```CBlockHeader```s can be used so that the test runner can deliver
+- Implement a (generator) function called `get_tests()` which yields `TestInstance`s.
+Each `TestInstance` consists of:
+  - a list of `[object, outcome, hash]` entries
+    * `object` is a `CBlock`, `CTransaction`, or
+    `CBlockHeader`.  `CBlock`'s and `CTransaction`'s are tested for
+    acceptance.  `CBlockHeader`s can be used so that the test runner can deliver
     complete headers-chains when requested from the bitcoind, to allow writing
     tests where blocks can be delivered out of order but still processed by
     headers-first bitcoind's.
-    * ```outcome``` is ```True```, ```False```, or ```None```.  If ```True```
-    or ```False```, the tip is compared with the expected tip -- either the
+    * `outcome` is `True`, `False`, or `None`.  If `True`
+    or `False`, the tip is compared with the expected tip -- either the
     block passed in, or the hash specified as the optional 3rd entry.  If
-    ```None``` is specified, then the test will compare all the bitcoind's
+    `None` is specified, then the test will compare all the bitcoind's
     being tested to see if they all agree on what the best tip is.
-    * ```hash``` is the block hash of the tip to compare against. Optional to
+    * `hash` is the block hash of the tip to compare against. Optional to
     specify; if left out then the hash of the block passed in will be used as
     the expected tip.  This allows for specifying an expected tip while testing
     the handling of either invalid blocks or blocks delivered out of order,
     which complete a longer chain.
-  - ```sync_every_block```: ```True/False```.  If ```False```, then all blocks
+  - `sync_every_block`: `True/False`.  If `False`, then all blocks
     are inv'ed together, and the test runner waits until the node receives the
     last one, and tests only the last block for tip acceptance using the
-    outcome and specified tip.  If ```True```, then each block is tested in
+    outcome and specified tip.  If `True`, then each block is tested in
     sequence and synced (this is slower when processing many blocks).
-  - ```sync_every_transaction```: ```True/False```.  Analogous to
-    ```sync_every_block```, except if the outcome on the last tx is "None",
+  - `sync_every_transaction`: `True/False`.  Analogous to
+    `sync_every_block`, except if the outcome on the last tx is "None",
     then the contents of the entire mempool are compared across all bitcoind
-    connections.  If ```True``` or ```False```, then only the last tx's
+    connections.  If `True` or `False`, then only the last tx's
     acceptance is tested against the given outcome.
 
-* For examples of tests written in this framework, see
-  ```invalidblockrequest.py``` and ```p2p-fullblocktest.py```.
+- For examples of tests written in this framework, see
+  `invalidblockrequest.py` and `p2p-fullblocktest.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 bitcoind.
+
+#### [test_framework/comptool.py](test_framework/comptool.py)
+Framework for comparison-tool style, P2P tests.
+
+#### [test_framework/script.py](test_framework/script.py)
+Utilities for manipulating transaction scripts (originally from python-bitcoinlib)
+
+#### [test_framework/blockstore.py](test_framework/blockstore.py)
+Implements disk-backed block and tx storage.
+
+#### [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.