Refactor iosim code so clock advancing is built-in.

src/twisted/test/iosim.py

@@ -6,7 +6,7 @@
 Utilities and helpers for simulating a network
 """
 
-
+from typing import Optional
 import itertools
 
 try:
@@ -20,6 +20,7 @@
 from twisted.internet.endpoints import TCP4ClientEndpoint, TCP4ServerEndpoint
 from twisted.internet.error import ConnectionRefusedError
 from twisted.internet.protocol import Factory, Protocol
+from twisted.internet.task import Clock
 from twisted.internet.testing import MemoryReactorClock
 from twisted.python.failure import Failure
 
@@ -284,12 +285,15 @@ class IOPump:
     Perhaps this is a utility worthy of being in protocol.py?
     """
 
-    def __init__(self, client, server, clientIO, serverIO, debug):
+    def __init__(self, client, server, clientIO, serverIO, debug, clock=None):
         self.client = client
         self.server = server
         self.clientIO = clientIO
         self.serverIO = serverIO
         self.debug = debug
+        if clock is None:
+            clock = MemoryReactorClock()
+        self.clock = clock
 
     def flush(self, debug=False):
         """
@@ -298,7 +302,7 @@ def flush(self, debug=False):
         Returns whether any data was moved.
         """
         result = False
-        for x in range(1000):
+        for _ in range(1000):
             if self.pump(debug):
                 result = True
             else:
@@ -309,10 +313,11 @@ def flush(self, debug=False):
 
     def pump(self, debug=False):
         """
-        Move data back and forth.
+        Move data back and forth, and increase clock slightly.
 
         Returns whether any data was moved.
         """
+        self.clock.advance(0.000001)
         if self.debug or debug:
             print("-- GLUG --")
         sData = self.serverIO.getOutBuffer()
@@ -356,6 +361,7 @@ def connect(
     clientTransport,
     debug=False,
     greet=True,
+    clock=None,
 ):
     """
     Create a new L{IOPump} connecting two protocols.
@@ -383,14 +389,22 @@ def connect(
         post-server-greeting state?
     @type greet: L{bool}
 
+    @param clock: An optional L{Clock}. Pumping the resulting L{IOPump} will
+        also increase clock time by a small increment.
+
     @return: An L{IOPump} which connects C{serverProtocol} and
         C{clientProtocol} and delivers bytes between them when it is pumped.
     @rtype: L{IOPump}
     """
     serverProtocol.makeConnection(serverTransport)
     clientProtocol.makeConnection(clientTransport)
     pump = IOPump(
-        clientProtocol, serverProtocol, clientTransport, serverTransport, debug
+        clientProtocol,
+        serverProtocol,
+        clientTransport,
+        serverTransport,
+        debug,
+        clock=clock,
     )
     if greet:
         # Kick off server greeting, etc
@@ -405,6 +419,7 @@ def connectedServerAndClient(
     serverTransportFactory=makeFakeServer,
     debug=False,
     greet=True,
+    clock: Optional[Clock] = None,
 ):
     """
     Connect a given server and client class to each other.
@@ -435,6 +450,9 @@ def connectedServerAndClient(
         post-server-greeting state?
     @type greet: L{bool}
 
+    @param clock: An optional L{Clock}. Pumping the resulting L{IOPump} will
+        also increase clock time by a small increment.
+
     @return: the client protocol, the server protocol, and an L{IOPump} which,
         when its C{pump} and C{flush} methods are called, will move data
         between the created client and server protocol instances.
@@ -444,7 +462,7 @@ def connectedServerAndClient(
     s = ServerClass()
     cio = clientTransportFactory(c)
     sio = serverTransportFactory(s)
-    return c, s, connect(s, sio, c, cio, debug, greet)
+    return c, s, connect(s, sio, c, cio, debug, greet, clock=clock)
 
 
 def _factoriesShouldConnect(clientInfo, serverInfo):

src/twisted/test/test_iosim.py

@@ -12,7 +12,8 @@
 
 from twisted.internet.interfaces import IPushProducer
 from twisted.internet.protocol import Protocol
-from twisted.test.iosim import FakeTransport, connect
+from twisted.internet.task import Clock
+from twisted.test.iosim import FakeTransport, connect, connectedServerAndClient
 from twisted.trial.unittest import TestCase
 
 
@@ -299,3 +300,15 @@ def test_clientStreamingProducer(self) -> None:
         (stream producer) registered with the client transport.
         """
         self._testStreamingProducer(mode="client")
+
+    def test_timeAdvances(self) -> None:
+        """
+        L{IOPump.pump} advances time in the given L{Clock}.
+        """
+        time_passed = []
+        clock = Clock()
+        _, _, pump = connectedServerAndClient(Protocol, Protocol, clock=clock)
+        clock.callLater(0, lambda: time_passed.append(True))
+        self.assertFalse(time_passed)
+        pump.pump()
+        self.assertTrue(time_passed)

src/twisted/test/test_sslverify.py

@@ -300,14 +300,8 @@ def connectionLost(self, reason):
     sProto, cProto, pump = connectedServerAndClient(
         lambda: serverFactory.buildProtocol(None),
         lambda: clientFactory.buildProtocol(None),
+        clock=clock
     )
-
-    # Need time to pass for flushing to work:
-    def flush(pump_flush=pump.flush):
-        clock.advance(0)
-        pump_flush()
-
-    pump.flush = flush
     pump.flush()
 
     return sProto, cProto, serverWrappedProto, clientWrappedProto, pump
@@ -2087,14 +2081,8 @@ def connectionLost(self, reason):
         cProto, sProto, pump = connectedServerAndClient(
             lambda: serverTLSFactory.buildProtocol(None),
             lambda: clientTLSFactory.buildProtocol(None),
+            clock=clock
         )
-
-        # Need time to pass for flushing to work:
-        def flush(pump_flush=pump.flush):
-            clock.advance(0)
-            pump_flush()
-
-        pump.flush = flush
         pump.flush()
 
         return cProto, sProto, clientWrappedProto, serverWrappedProto, pump

src/twisted/web/test/test_agent.py

@@ -892,8 +892,14 @@ def accumulator():
         wrapper = serverWrapper(accumulator, reactor).buildProtocol(None)
         serverTransport = FakeTransport(wrapper, True)
         wrapper.makeConnection(serverTransport)
-        pump = IOPump(clientProtocol, wrapper, clientTransport, serverTransport, False)
-        reactor.advance(0)
+        pump = IOPump(
+            clientProtocol,
+            wrapper,
+            clientTransport,
+            serverTransport,
+            False,
+            clock=reactor,
+        )
         pump.flush()
         self.assertNoResult(deferred)
         lines = accumulator.currentProtocol.data.split(b"\r\n")
@@ -907,7 +913,6 @@ def accumulator():
             b"\r\nContent-length: 12\r\n\r\n"
             b"hello world!"
         )
-        reactor.advance(0)
         pump.flush()
         response = self.successResultOf(deferred)
         self.assertEquals(