Added touch event permutations test to touch_exploration_controller.

ui/chromeos/touch_exploration_controller_unittest.cc

Index: ui/chromeos/touch_exploration_controller_unittest.cc
diff --git a/ui/chromeos/touch_exploration_controller_unittest.cc b/ui/chromeos/touch_exploration_controller_unittest.cc
index 10da4b1f3a7f5a272d86d88d1a10daae2f1d1e22..fcf0bb20f9c730b5b20b778a09b9cbe6c97ff849 100644
--- a/ui/chromeos/touch_exploration_controller_unittest.cc
+++ b/ui/chromeos/touch_exploration_controller_unittest.cc
@@ -13,6 +13,7 @@
 #include "ui/aura/window.h"
 #include "ui/events/event.h"
 #include "ui/events/event_utils.h"
+#include "ui/events/test/events_test_utils.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_surface.h"
@@ -57,6 +58,16 @@ class EventCapturer : public ui::EventHandler {
   DISALLOW_COPY_AND_ASSIGN(EventCapturer);
 };
 
+int Factorial(int n) {
+  if (n <= 0)
+    return 0;
+  if (n == 1)
+    return 1;
+  if (n == 2)
+      return 2;
+  return n * Factorial(n - 1);
+}
+
 }  // namespace
 
 class TouchExplorationTest : public aura::test::AuraTestBase {
@@ -948,4 +959,86 @@ TEST_F(TouchExplorationTest, Passthrough) {
   EXPECT_TRUE(IsInNoFingersDownState());
 }
 
+TEST_F(TouchExplorationTest, AllFingerPermutations) {
+  SwitchTouchExplorationMode(true);
+
+  // We will test all permutations of events from three different fingers
+  // to ensure that we return to NO_FINGERS_DOWN when fingers have been
+  // released.
+  ScopedVector<ui::TouchEvent> all_events;
+  all_events.push_back(

[aboxhall, 2014/06/27 18:08:02]

This could be a for-loop over touch_id - it'd also solve the "what's that third
argument again" mystery (I had to look it up).

[evy, 2014/06/27 21:00:03]

Done. Great idea.

+      new TouchEvent(ui::ET_TOUCH_PRESSED, gfx::Point(11, 12), 0, Now()));
+  all_events.push_back(
+      new TouchEvent(ui::ET_TOUCH_MOVED, gfx::Point(13, 14), 0, Now()));
+  all_events.push_back(
+      new TouchEvent(ui::ET_TOUCH_RELEASED, gfx::Point(15, 16), 0, Now()));
+  all_events.push_back(
+      new TouchEvent(ui::ET_TOUCH_PRESSED, gfx::Point(21, 22), 1, Now()));
+  all_events.push_back(
+      new TouchEvent(ui::ET_TOUCH_MOVED, gfx::Point(23, 24), 1, Now()));
+  all_events.push_back(
+      new TouchEvent(ui::ET_TOUCH_RELEASED, gfx::Point(25, 26), 1, Now()));
+  all_events.push_back(
+      new TouchEvent(ui::ET_TOUCH_PRESSED, gfx::Point(31, 32), 2, Now()));
+  all_events.push_back(
+      new TouchEvent(ui::ET_TOUCH_MOVED, gfx::Point(33, 34), 2, Now()));
+  all_events.push_back(
+      new TouchEvent(ui::ET_TOUCH_RELEASED, gfx::Point(35, 36), 2, Now()));
+
+  const int num_events = all_events.size();
+  const int num_permutations = Factorial(num_events);
+
+  for (int i = 0; i < num_permutations; i++) {

[aboxhall, 2014/06/27 18:08:02]

Since this is not used as a simple index on the next line, perhaps name it 'p'
or something more descriptive as a reminder of what it represents. (Then 'j'
could become 'i' - since it doesn't really represent something straightforward I
couldn't think of a more readable name for it.)

(In emacs, in case you haven't come across this before: 
M-< 
M-x replace-regexp
\bi\b
p
- or whatever you want the new variable to be called)

[evy, 2014/06/27 21:00:03]

Done.

+    std::vector<ui::TouchEvent*> queued_events = all_events.get();
+    std::vector<bool> fingers_pressed(3, false);

[aboxhall, 2014/06/27 18:08:01]

My favourite vector constructor!

[evy, 2014/06/27 21:00:03]

:D

+    // current_factorial starts at factorial(num_events - 1)
+    // and decreases each iteration
+    int current_factorial = num_permutations/num_events;
+    for (int j = num_events - 1; j >= 0; j--) {

[aboxhall, 2014/06/27 18:08:02]

I can't fully understand this code (just the bit about calculating |index|), so
I can't work through whether it's correct or not. Could you write an explanation
of what it's doing?

[evy, 2014/06/27 21:00:03]

I renamed some variables and added tons of comments - let me know what you
think!

+      int index;
+      if (j == num_events - 1) {

[aboxhall, 2014/06/27 18:08:02]

This could be a switch statement (and you could pull num_events - 1 out into a
variable named something like last_event to make it easier to visually parse).

[evy, 2014/06/27 21:00:03]

I'm not sure if this comment applies - can you read over my new explanations and
if you still want a switch statement let me know what you mean?

+        index = i / current_factorial;
+        current_factorial /= j;
+      } else if (j == 0) {
+        index = 0;
+      } else {
+        index = (i % (current_factorial * (j + 1)) / current_factorial);
+        current_factorial /= j;
+      }
+      ui::TouchEvent* next_dispatch = queued_events[index];
+      ASSERT_TRUE(next_dispatch != NULL);
+      EventTestApi test_dispatch(next_dispatch);
+      test_dispatch.set_time_stamp(Now());
+      generator_->Dispatch(next_dispatch);
+      queued_events.erase(queued_events.begin() + index);
+      // Note: it is possible to send a touched move event in the state
+      // SINGLE_TAP_RELEASED or TOUCH_EXPLORE_RELEASED
+      // because the events are not always generated in a sensical
+      // order. If there is a NOTREACHED() for touch moved hit in

[aboxhall, 2014/06/27 18:08:01]

Will NOTREACHED() cause the test to crash in debug mode?

[evy, 2014/06/27 21:00:03]

Yup - I just fixed that problem, but forgot to change this comment. Thanks!

+      // InSingleTapOrTouchExploreReleased, that is fine here.
+
+      // Keep track of what fingers have been pressed, to release
+      // only those fingers at the end, so the check for being in
+      // no fingers down can be accurate.
+      if (next_dispatch->type() == ET_TOUCH_PRESSED) {
+        fingers_pressed[next_dispatch->touch_id()] = true;
+      } else if (next_dispatch->type() == ET_TOUCH_RELEASED) {
+        fingers_pressed[next_dispatch->touch_id()] = false;
+      }
+    }
+    ASSERT_EQ(queued_events.size(), 0u);
+
+    // Release fingers recorded as pressed.
+    for(int j = 0; j < int(fingers_pressed.size()); j++){
+      if (fingers_pressed[j] == true) {
+        generator_->ReleaseTouchId(j);
+        fingers_pressed[j] = false;
+      }
+    }
+    AdvanceSimulatedTimePastTapDelay();
+    EXPECT_TRUE(IsInNoFingersDownState());
+    ClearCapturedEvents();
+  }
+}
+
 }  // namespace ui