Fixed flaky StunRequestTests which depended on the wall clock

webrtc/p2p/base/stunrequest_unittest.cc

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/p2p/base/stunrequest.h"
+#include "webrtc/base/fakeclock.h"
 #include "webrtc/base/gunit.h"
 #include "webrtc/base/helpers.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/ssladapter.h"
 #include "webrtc/base/timeutils.h"
 
 using namespace cricket;
 
-// STUN timeout (with all retries) is 9500ms.
-// Add some margin of error for slow bots.
-// TODO(deadbeef): Use simulated clock instead of just increasing timeouts to
-// fix flaky tests.
-static const int kTimeoutMs = 15000;
-
 class StunRequestTest : public testing::Test,
                         public sigslot::has_slots<> {
  public:
   StunRequestTest()
       : manager_(rtc::Thread::Current()),
         request_count_(0), response_(NULL),
         success_(false), failure_(false), timeout_(false) {
     manager_.SignalSendPacket.connect(this, &StunRequestTest::OnSendPacket);
   }
 
@@ skipping 107 matching lines @@
   EXPECT_TRUE(response_ == NULL);
   EXPECT_FALSE(success_);
   EXPECT_FALSE(failure_);
   EXPECT_FALSE(timeout_);
   delete res;
 }
 
 // Test that requests are sent at the right times, and that the 9th request
 // (sent at 7900 ms) can be properly replied to.
 TEST_F(StunRequestTest, TestBackoff) {
+  const int MAX_TIMEOUT_MS = 10000;
+  rtc::ScopedFakeClock fake_clock;
   StunMessage* req = CreateStunMessage(STUN_BINDING_REQUEST, NULL);
 
   int64_t start = rtc::TimeMillis();
   manager_.Send(new StunRequestThunker(req, this));
   StunMessage* res = CreateStunMessage(STUN_BINDING_RESPONSE, req);
   for (int i = 0; i < 9; ++i) {
-    while (request_count_ == i)
-      rtc::Thread::Current()->ProcessMessages(1);
+    EXPECT_TRUE_SIMULATED_WAIT(request_count_ != i, MAX_TIMEOUT_MS, fake_clock);
     int64_t elapsed = rtc::TimeMillis() - start;
     LOG(LS_INFO) << "STUN request #" << (i + 1)
                  << " sent at " << elapsed << " ms";
-    EXPECT_GE(TotalDelay(i + 1), elapsed);
+    EXPECT_EQ(TotalDelay(i), elapsed);
   }
   EXPECT_TRUE(manager_.CheckResponse(res));
 
   EXPECT_TRUE(response_ == res);
   EXPECT_TRUE(success_);
   EXPECT_FALSE(failure_);
   EXPECT_FALSE(timeout_);
   delete res;
 }
 
 // Test that we timeout properly if no response is received in 9500 ms.
 TEST_F(StunRequestTest, TestTimeout) {
+  rtc::ScopedFakeClock fake_clock;
   StunMessage* req = CreateStunMessage(STUN_BINDING_REQUEST, NULL);
   StunMessage* res = CreateStunMessage(STUN_BINDING_RESPONSE, req);
 
   manager_.Send(new StunRequestThunker(req, this));
-  rtc::Thread::Current()->ProcessMessages(kTimeoutMs);
+  // Simulate the 9500 ms STUN timeout
+  SIMULATED_WAIT(false, 9500, fake_clock);
+
   EXPECT_FALSE(manager_.CheckResponse(res));
-
   EXPECT_TRUE(response_ == NULL);
   EXPECT_FALSE(success_);
   EXPECT_FALSE(failure_);
   EXPECT_TRUE(timeout_);
   delete res;
 }
 
 // Regression test for specific crash where we receive a response with the
 // same id as a request that doesn't have an underlying StunMessage yet.
 TEST_F(StunRequestTest, TestNoEmptyRequest) {
   StunRequestThunker* request = new StunRequestThunker(this);
 
   manager_.SendDelayed(request, 100);
 
   StunMessage dummy_req;
   dummy_req.SetTransactionID(request->id());
   StunMessage* res = CreateStunMessage(STUN_BINDING_RESPONSE, &dummy_req);
 
   EXPECT_TRUE(manager_.CheckResponse(res));
 
   EXPECT_TRUE(response_ == res);
   EXPECT_TRUE(success_);
   EXPECT_FALSE(failure_);
   EXPECT_FALSE(timeout_);
   delete res;
 }