Add demo of attack on BA liveness

issue: amiller/HoneyBadgerBFT#59

test/demo_attack_issue59.py

@@ -0,0 +1,57 @@
+import random
+
+import gevent
+from gevent.queue import Queue
+from pytest import mark
+
+
+@mark.demo
+def test_issue59_attack_demo(mocker, monkeypatch):
+    from .byzantine import byz_ba_issue_59, broadcast_router
+    from .test_binaryagreement import _make_coins
+    from honeybadgerbft.core import binaryagreement
+
+    def mocked_conf_message_receiver(**kwargs):
+        pass
+
+    def mocked_conf_phase_handler(**kwargs):
+        return kwargs['values']
+
+    monkeypatch.setattr(
+        binaryagreement, 'handle_conf_messages', mocked_conf_message_receiver)
+    monkeypatch.setattr(
+        binaryagreement, 'wait_for_conf_values', mocked_conf_phase_handler)
+
+    N = 4
+    f = 1
+    seed = None
+    sid = 'sidA'
+    rnd = random.Random(seed)
+    sends, recvs = broadcast_router(N)
+    threads = []
+    inputs = []
+    outputs = []
+
+    coins_seed = rnd.random()
+    coins = _make_coins(sid+'COIN', N, f, coins_seed)
+
+    for i in range(4):
+        inputs.append(Queue())
+        outputs.append(Queue())
+
+    byz_thread = gevent.spawn(byz_ba_issue_59, sid, 3, N, f, coins[3],
+                              inputs[3].get, outputs[3].put_nowait, sends[3], recvs[3])
+    threads.append(byz_thread)
+
+    for i in (2, 0, 1):
+        t = gevent.spawn(binaryagreement.binaryagreement, sid, i, N, f, coins[i],
+                         inputs[i].get, outputs[i].put_nowait, sends[i], recvs[i])
+        threads.append(t)
+
+    inputs[0].put(0)    # A_0
+    inputs[1].put(0)    # A_1
+    inputs[2].put(1)    # B
+    inputs[3].put(0)    # F (x)
+
+    for i in range(N):
+        outputs[i].get()