[tests] add example test

test/functional/example_test.py

@@ -0,0 +1,219 @@
+#!/usr/bin/env python3
+# Copyright (c) 2017 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""An example functional test
+
+The module-level docstring should include a high-level description of
+what the test is doing. It's the first thing people see when they open
+the file and should give the reader information about *what* the test
+is testing and *how* it's being tested
+"""
+# Imports should be in PEP8 ordering (std library first, then third party
+# libraries then local imports).
+from collections import defaultdict
+
+# Avoid wildcard * imports if possible
+from test_framework.blocktools import (create_block, create_coinbase)
+from test_framework.mininode import (
+    CInv,
+    NetworkThread,
+    NodeConn,
+    NodeConnCB,
+    mininode_lock,
+    msg_block,
+    msg_getdata,
+    wait_until,
+)
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+    connect_nodes,
+    p2p_port,
+)
+
+# NodeConnCB is a class containing callbacks to be executed when a P2P
+# message is received from the node-under-test. Subclass NodeConnCB and
+# override the on_*() methods if you need custom behaviour.
+class BaseNode(NodeConnCB):
+    def __init__(self):
+        """Initialize the NodeConnCB
+
+        Used to inialize custom properties for the Node that aren't
+        included by default in the base class. Be aware that the NodeConnCB
+        base class already stores a counter for each P2P message type and the
+        last received message of each type, which should be sufficient for the
+        needs of most tests.
+
+        Call super().__init__() first for standard initialization and then
+        initialize custom properties."""
+        super().__init__()
+        # Stores a dictionary of all blocks received
+        self.block_receive_map = defaultdict(int)
+
+    def on_block(self, conn, message):
+        """Override the standard on_block callback
+
+        Store the hash of a received block in the dictionary."""
+        message.block.calc_sha256()
+        self.block_receive_map[message.block.sha256] += 1
+
+def custom_function():
+    """Do some custom behaviour
+
+    If this function is more generally useful for other tests, consider
+    moving it to a module in test_framework."""
+    # self.log.info("running custom_function")  # Oops! Can't run self.log outside the BitcoinTestFramework
+    pass
+
+class ExampleTest(BitcoinTestFramework):
+    # Each functional test is a subclass of the BitcoinTestFramework class.
+
+    # Override the __init__(), add_options(), setup_chain(), setup_network()
+    # and setup_nodes() methods to customize the test setup as required.
+
+    def __init__(self):
+        """Initialize the test
+
+        Call super().__init__() first, and then override any test parameters
+        for your individual test."""
+        super().__init__()
+        self.setup_clean_chain = True
+        self.num_nodes = 3
+        # Use self.extra_args to change command-line arguments for the nodes
+        self.extra_args = [[], ["-logips"], []]
+
+        # self.log.info("I've finished __init__")  # Oops! Can't run self.log before run_test()
+
+    # Use add_options() to add specific command-line options for your test.
+    # In practice this is not used very much, since the tests are mostly written
+    # to be run in automated environments without command-line options.
+    # def add_options()
+    #     pass
+
+    # Use setup_chain() to customize the node data directories. In practice
+    # this is not used very much since the default behaviour is almost always
+    # fine
+    # def setup_chain():
+    #     pass
+
+    def setup_network(self):
+        """Setup the test network topology
+
+        Often you won't need to override this, since the standard network topology
+        (linear: node0 <-> node1 <-> node2 <-> ...) is fine for most tests.
+
+        If you do override this method, remember to start the nodes, assign
+        them to self.nodes, connect them and then sync."""
+
+        self.setup_nodes()
+
+        # In this test, we're not connecting node2 to node0 or node1. Calls to
+        # sync_all() should not include node2, since we're not expecting it to
+        # sync.
+        connect_nodes(self.nodes[0], 1)
+        self.sync_all([self.nodes[0:1]])
+
+    # Use setup_nodes() to customize the node start behaviour (for example if
+    # you don't want to start all nodes at the start of the test).
+    # def setup_nodes():
+    #     pass
+
+    def custom_method(self):
+        """Do some custom behaviour for this test
+
+        Define it in a method here because you're going to use it repeatedly.
+        If you think it's useful in general, consider moving it to the base
+        BitcoinTestFramework class so other tests can use it."""
+
+        self.log.info("Running custom_method")
+
+    def run_test(self):
+        """Main test logic"""
+
+        # Create a P2P connection to one of the nodes
+        node0 = BaseNode()
+        connections = []
+        connections.append(NodeConn('127.0.0.1', p2p_port(0), self.nodes[0], node0))
+        node0.add_connection(connections[0])
+
+        # Start up network handling in another thread. This needs to be called
+        # after the P2P connections have been created.
+        NetworkThread().start()
+        # wait_for_verack ensures that the P2P connection is fully up.
+        node0.wait_for_verack()
+
+        # Generating a block on one of the nodes will get us out of IBD
+        blocks = [int(self.nodes[0].generate(nblocks=1)[0], 16)]
+        self.sync_all([self.nodes[0:1]])
+
+        # Notice above how we called an RPC by calling a method with the same
+        # name on the node object. Notice also how we used a keyword argument
+        # to specify a named RPC argument. Neither of those are defined on the
+        # node object. Instead there's some __getattr__() magic going on under
+        # the covers to dispatch unrecognised attribute calls to the RPC
+        # interface.
+
+        # Logs are nice. Do plenty of them. They can be used in place of comments for
+        # breaking the test into sub-sections.
+        self.log.info("Starting test!")
+
+        self.log.info("Calling a custom function")
+        custom_function()
+
+        self.log.info("Calling a custom method")
+        self.custom_method()
+
+        self.log.info("Create some blocks")
+        self.tip = int(self.nodes[0].getbestblockhash(), 16)
+        self.block_time = self.nodes[0].getblock(self.nodes[0].getbestblockhash())['time'] + 1
+
+        height = 1
+
+        for i in range(10):
+            # Use the mininode and blocktools functionality to manually build a block
+            # Calling the generate() rpc is easier, but this allows us to exactly
+            # control the blocks and transactions.
+            block = create_block(self.tip, create_coinbase(height), self.block_time)
+            block.solve()
+            block_message = msg_block(block)
+            # Send message is used to send a P2P message to the node over our NodeConn connection
+            node0.send_message(block_message)
+            self.tip = block.sha256
+            blocks.append(self.tip)
+            self.block_time += 1
+            height += 1
+
+        self.log.info("Wait for node1 to reach current tip (height 11) using RPC")
+        self.nodes[1].waitforblockheight(11)
+
+        self.log.info("Connect node2 and node1")
+        connect_nodes(self.nodes[1], 2)
+
+        self.log.info("Add P2P connection to node2")
+        node2 = BaseNode()
+        connections.append(NodeConn('127.0.0.1', p2p_port(2), self.nodes[2], node2))
+        node2.add_connection(connections[1])
+        node2.wait_for_verack()
+
+        self.log.info("Wait for node2 reach current tip. Test that it has propogated all the blocks to us")
+
+        for block in blocks:
+            getdata_request = msg_getdata()
+            getdata_request.inv.append(CInv(2, block))
+            node2.send_message(getdata_request)
+
+        # wait_until() will loop until a predicate condition is met. Use it to test properties of the
+        # NodeConnCB objects.
+        assert wait_until(lambda: sorted(blocks) == sorted(list(node2.block_receive_map.keys())), timeout=5)
+
+        self.log.info("Check that each block was received only once")
+        # The network thread uses a global lock on data access to the NodeConn objects when sending and receiving
+        # messages. The test thread should acquire the global lock before accessing any NodeConn data to avoid locking
+        # and synchronization issues. Note wait_until() acquires this global lock when testing the predicate.
+        with mininode_lock:
+            for block in node2.block_receive_map.values():
+                assert_equal(block, 1)
+
+if __name__ == '__main__':
+    ExampleTest().main()

test/functional/test_runner.py

@@ -137,6 +137,7 @@ EXTENDED_SCRIPTS = [
     'bip65-cltv-p2p.py',
     'bipdersig-p2p.py',
     'bipdersig.py',
+    'example_test.py',
     'getblocktemplate_proposals.py',
     'txn_doublespend.py',
     'txn_clone.py --mineblock',