1 files changed, 89 insertions, 0 deletions
diff --git a/test/functional/feature_minchainwork.py b/test/functional/feature_minchainwork.py
new file mode 100755
index 0000000000..90a3de0e0d
--- /dev/null
+++ b/test/functional/feature_minchainwork.py
@@ -0,0 +1,89 @@
+#!/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.
+"""Test logic for setting nMinimumChainWork on command line.
+
+Nodes don't consider themselves out of "initial block download" until
+their active chain has more work than nMinimumChainWork.
+
+Nodes don't download blocks from a peer unless the peer's best known block
+has more work than nMinimumChainWork.
+
+While in initial block download, nodes won't relay blocks to their peers, so
+test that this parameter functions as intended by verifying that block relay
+only succeeds past a given node once its nMinimumChainWork has been exceeded.
+"""
+
+import time
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import connect_nodes, assert_equal
+
+# 2 hashes required per regtest block (with no difficulty adjustment)
+REGTEST_WORK_PER_BLOCK = 2
+
+class MinimumChainWorkTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 3
+
+        self.extra_args = [[], ["-minimumchainwork=0x65"], ["-minimumchainwork=0x65"]]
+        self.node_min_work = [0, 101, 101]
+
+    def setup_network(self):
+        # This test relies on the chain setup being:
+        # node0 <- node1 <- node2
+        # Before leaving IBD, nodes prefer to download blocks from outbound
+        # peers, so ensure that we're mining on an outbound peer and testing
+        # block relay to inbound peers.
+        self.setup_nodes()
+        for i in range(self.num_nodes-1):
+            connect_nodes(self.nodes[i+1], i)
+
+    def run_test(self):
+        # Start building a chain on node0.  node2 shouldn't be able to sync until node1's
+        # minchainwork is exceeded
+        starting_chain_work = REGTEST_WORK_PER_BLOCK # Genesis block's work
+        self.log.info("Testing relay across node %d (minChainWork = %d)", 1, self.node_min_work[1])
+
+        starting_blockcount = self.nodes[2].getblockcount()
+
+        num_blocks_to_generate = int((self.node_min_work[1] - starting_chain_work) / REGTEST_WORK_PER_BLOCK)
+        self.log.info("Generating %d blocks on node0", num_blocks_to_generate)
+        hashes = self.nodes[0].generate(num_blocks_to_generate)
+
+        self.log.info("Node0 current chain work: %s", self.nodes[0].getblockheader(hashes[-1])['chainwork'])
+
+        # Sleep a few seconds and verify that node2 didn't get any new blocks
+        # or headers.  We sleep, rather than sync_blocks(node0, node1) because
+        # it's reasonable either way for node1 to get the blocks, or not get
+        # them (since they're below node1's minchainwork).
+        time.sleep(3)
+
+        self.log.info("Verifying node 2 has no more blocks than before")
+        self.log.info("Blockcounts: %s", [n.getblockcount() for n in self.nodes])
+        # Node2 shouldn't have any new headers yet, because node1 should not
+        # have relayed anything.
+        assert_equal(len(self.nodes[2].getchaintips()), 1)
+        assert_equal(self.nodes[2].getchaintips()[0]['height'], 0)
+
+        assert self.nodes[1].getbestblockhash() != self.nodes[0].getbestblockhash()
+        assert_equal(self.nodes[2].getblockcount(), starting_blockcount)
+
+        self.log.info("Generating one more block")
+        self.nodes[0].generate(1)
+
+        self.log.info("Verifying nodes are all synced")
+
+        # Because nodes in regtest are all manual connections (eg using
+        # addnode), node1 should not have disconnected node0. If not for that,
+        # we'd expect node1 to have disconnected node0 for serving an
+        # insufficient work chain, in which case we'd need to reconnect them to
+        # continue the test.
+
+        self.sync_all()
+        self.log.info("Blockcounts: %s", [n.getblockcount() for n in self.nodes])
+
+if __name__ == '__main__':
+    MinimumChainWorkTest().main()