[tests] Fix intermittent rpc_net.py failure.

rpc_net.py would intermittently fail on Travis, probably
due to assuming that two consecutive RPC calls were atomic.
Fix this by only testing that amounts are bounded above and
below rather than equal.

Author: jnewbery

test/functional/rpc_net.py

@@ -10,6 +10,7 @@
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
+    assert_greater_than_or_equal,
     assert_raises_rpc_error,
     connect_nodes_bi,
     p2p_port,
@@ -33,26 +34,34 @@ def _test_connection_count(self):
         assert_equal(self.nodes[0].getconnectioncount(), 2)
 
     def _test_getnettotals(self):
-        # check that getnettotals totalbytesrecv and totalbytessent
-        # are consistent with getpeerinfo
+        # getnettotals totalbytesrecv and totalbytessent should be
+        # consistent with getpeerinfo. Since the RPC calls are not atomic,
+        # and messages might have been recvd or sent between RPC calls, call
+        # getnettotals before and after and verify that the returned values
+        # from getpeerinfo are bounded by those values.
+        net_totals_before = self.nodes[0].getnettotals()
         peer_info = self.nodes[0].getpeerinfo()
+        net_totals_after = self.nodes[0].getnettotals()
         assert_equal(len(peer_info), 2)
-        net_totals = self.nodes[0].getnettotals()
-        assert_equal(sum([peer['bytesrecv'] for peer in peer_info]),
-                     net_totals['totalbytesrecv'])
-        assert_equal(sum([peer['bytessent'] for peer in peer_info]),
-                     net_totals['totalbytessent'])
+        peers_recv = sum([peer['bytesrecv'] for peer in peer_info])
+        peers_sent = sum([peer['bytessent'] for peer in peer_info])
+
+        assert_greater_than_or_equal(peers_recv, net_totals_before['totalbytesrecv'])
+        assert_greater_than_or_equal(net_totals_after['totalbytesrecv'], peers_recv)
+        assert_greater_than_or_equal(peers_sent, net_totals_before['totalbytessent'])
+        assert_greater_than_or_equal(net_totals_after['totalbytessent'], peers_sent)
+
         # test getnettotals and getpeerinfo by doing a ping
         # the bytes sent/received should change
         # note ping and pong are 32 bytes each
         self.nodes[0].ping()
-        wait_until(lambda: (net_totals['totalbytessent'] + 32*2) == self.nodes[0].getnettotals()['totalbytessent'], timeout=1)
-        wait_until(lambda: (net_totals['totalbytesrecv'] + 32*2) == self.nodes[0].getnettotals()['totalbytesrecv'], timeout=1)
+        wait_until(lambda: (self.nodes[0].getnettotals()['totalbytessent'] >= net_totals_after['totalbytessent'] + 32 * 2), timeout=1)
+        wait_until(lambda: (self.nodes[0].getnettotals()['totalbytesrecv'] >= net_totals_after['totalbytesrecv'] + 32 * 2), timeout=1)
 
         peer_info_after_ping = self.nodes[0].getpeerinfo()
         for before, after in zip(peer_info, peer_info_after_ping):
-            assert_equal(before['bytesrecv_per_msg']['pong'] + 32, after['bytesrecv_per_msg']['pong'])
-            assert_equal(before['bytessent_per_msg']['ping'] + 32, after['bytessent_per_msg']['ping'])
+            assert_greater_than_or_equal(after['bytesrecv_per_msg']['pong'], before['bytesrecv_per_msg']['pong'] + 32)
+            assert_greater_than_or_equal(after['bytessent_per_msg']['ping'], before['bytessent_per_msg']['ping'] + 32)
 
     def _test_getnetworkinginfo(self):
         assert_equal(self.nodes[0].getnetworkinfo()['networkactive'], True)
@@ -78,8 +87,7 @@ def _test_getaddednodeinfo(self):
         assert_equal(len(added_nodes), 1)
         assert_equal(added_nodes[0]['addednode'], ip_port)
         # check that a non-existent node returns an error
-        assert_raises_rpc_error(-24, "Node has not been added",
-                              self.nodes[0].getaddednodeinfo, '1.1.1.1')
+        assert_raises_rpc_error(-24, "Node has not been added", self.nodes[0].getaddednodeinfo, '1.1.1.1')
 
     def _test_getpeerinfo(self):
         peer_info = [x.getpeerinfo() for x in self.nodes]