Coalesced mouse wheel event has the position of the most recent event.

content/common/input/event_with_latency_info_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/common/input/event_with_latency_info.h"
 
 #include <limits>
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
@@ skipping 295 matching lines @@
   // WebMouseWheelEvent objects with same values except different deltaX and
   // deltaY should coalesce.
   EXPECT_TRUE(CanCoalesce(mouse_wheel_0, mouse_wheel_1));
 
   // WebMouseWheelEvent objects with different modifiers should not coalesce.
   mouse_wheel_0 = CreateMouseWheel(1, 1);
   mouse_wheel_1 = CreateMouseWheel(1, 1);
   mouse_wheel_0.event.modifiers = WebInputEvent::ControlKey;
   mouse_wheel_1.event.modifiers = WebInputEvent::ShiftKey;
   EXPECT_FALSE(CanCoalesce(mouse_wheel_0, mouse_wheel_1));
+
+  // Coalesced event has the position of the most recent event.
+  mouse_wheel_0 = CreateMouseWheel(1, 1);
+  mouse_wheel_0.event.x = 1;
+  mouse_wheel_0.event.y = 1;
+  mouse_wheel_1 = CreateMouseWheel(2, 2);
+  mouse_wheel_1.event.x = 2;
+  mouse_wheel_1.event.y = 2;
+  EXPECT_TRUE(CanCoalesce(mouse_wheel_0, mouse_wheel_1));
+  Coalesce(mouse_wheel_0, &mouse_wheel_1);

[dtapuska, 2016/08/19 01:41:41]

Ultimately this coalescing test could probably be a little more verbose checking
the delta and the other items are added correctly..

And testing that all the conditionals of CanCoalese are tested.

[tdresser, 2016/08/19 12:43:30]

The naming here is a bit confusing.

We might want to rename the events something like mouse_wheel_old,
mouse_wheel_new.

[sahel, 2016/08/19 15:17:56]

Done.

[sahel, 2016/08/19 15:17:57]

Then naming is consistent with the rest of the unittests. I'll change the names
of the events for all unittests to be more meaningful in a separate patch. 

+  EXPECT_EQ(1, mouse_wheel_1.event.x);
+  EXPECT_EQ(1, mouse_wheel_1.event.y);
 }
 
 // Coalescing preserves the newer timestamp.
 TEST_F(EventWithLatencyInfoTest, TimestampCoalescing) {
   MouseWheelEventWithLatencyInfo mouse_wheel_0 = CreateMouseWheel(1, 1);
   mouse_wheel_0.event.timeStampSeconds = 5.0;
   MouseWheelEventWithLatencyInfo mouse_wheel_1 = CreateMouseWheel(2, 2);
   mouse_wheel_1.event.timeStampSeconds = 10.0;
 
   EXPECT_TRUE(CanCoalesce(mouse_wheel_0, mouse_wheel_1));
   Coalesce(mouse_wheel_1, &mouse_wheel_0);
   EXPECT_EQ(10.0, mouse_wheel_0.event.timeStampSeconds);
 }
 
 }  // namespace
 }  // namespace content