MacViews: Fix sending mouse exit event and releasing capture on D&D.

ui/views/cocoa/drag_drop_client_mac_unittest.mm

Index: ui/views/cocoa/drag_drop_client_mac_unittest.mm
diff --git a/ui/views/cocoa/drag_drop_client_mac_unittest.mm b/ui/views/cocoa/drag_drop_client_mac_unittest.mm
index 0f9341305eb607ed359b72a4bf82188650123c9e..48875734c549ce54f476246d29c614bed7e34f3f 100644
--- a/ui/views/cocoa/drag_drop_client_mac_unittest.mm
+++ b/ui/views/cocoa/drag_drop_client_mac_unittest.mm
@@ -6,8 +6,11 @@
 
 #import <Cocoa/Cocoa.h>
 
+#import "base/mac/scoped_objc_class_swizzler.h"
 #include "base/mac/sdk_forward_declarations.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "ui/events/test/event_generator.h"
 #import "ui/views/cocoa/bridged_native_widget.h"
 #include "ui/views/test/widget_test.h"
 #include "ui/views/view.h"
@@ -16,6 +19,18 @@
 
 using base::ASCIIToUTF16;
 
+@interface NSView (DragSessionTestingDonor)
+@end
+
+@implementation NSView (DragSessionTestingDonor)
+- (NSDraggingSession*)cr_beginDraggingSessionWithItems:(NSArray*)items
+                                                 event:(NSEvent*)event
+                                                source:(id<NSDraggingSource>)
+                                                           source {
+  return nil;
+}
+@end
+
 // Mocks the NSDraggingInfo sent to the DragDropClientMac's DragUpdate() and
 // Drop() methods. Out of the required methods of the protocol, only
 // draggingLocation and draggingPasteboard are used.
@@ -209,6 +224,45 @@ TEST_F(DragDropClientMacTest, BasicDragDrop) {
   EXPECT_EQ(Drop(), NSDragOperationMove);
 }
 
+// Tests that widget releases mouse capture when drag'n'drop is started.

[tapted, 2016/09/21 10:07:05]

Since StartDragAndDrop() spins the runloop, the test is actually testing that
capture is released by the time the drag ends - but that's what we want :). E.g.
this should say

// Ensure that capture is released before the end of a drag and drop operation.

[snake, 2016/09/21 12:29:52]

Done.

+TEST_F(DragDropClientMacTest, ReleaseCapture) {
+  ui::test::EventGenerator event_generator(GetContext(),
+                                           widget_->GetNativeWindow());
+  // Generate mouse press to toggle dragging_ flag in BaseView.

[tapted, 2016/09/21 10:07:05]

this comment is out of date

[snake, 2016/09/21 12:29:52]

Done.

+  // StartDragAndDrop() should disable it.
+  event_generator.MoveMouseTo(gfx::Point(50, 50));
+  event_generator.PressLeftButton();
+
+  // DragDropView doesn't actually capture the mouse, so explicitly acquire it
+  // to test that StartDragAndDrop() actually releases it.
+  bridge_->AcquireCapture();

[tapted, 2016/09/21 10:07:05]

Be aware that capture on Windows typically can't be tested in non-interactive
tests - the problem otherwise is that other tests may be running in parallel,
posting their own mouse events that will be captured. For Mac.. I suppose this
is OK since the drag should exit before any events could get captured. But
that's worth a comment here. E.g.

// Although this is not an interactive UI test, acquiring capture should be OK
// since the runloop will exit before the system has any opportunity to capture
anything.

[snake, 2016/09/21 12:29:52]

Done.

+  EXPECT_TRUE(bridge_->HasCapture());
+
+  // Create the drop data
+  OSExchangeData data;
+  const base::string16& text = ASCIIToUTF16("text");
+  data.SetString(text);
+  SetData(data);
+
+  // There's no way to cleanly stop NSDraggingSession inside unit tests, so just
+  // don't start it at all.
+  base::mac::ScopedObjCClassSwizzler swizzle(
+      [NSView class], @selector(beginDraggingSessionWithItems:event:source:),
+      @selector(cr_beginDraggingSessionWithItems:event:source:));
+
+  // Immediately quit drag'n'drop, or we'll hang.
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(&DragDropClientMac::EndDrag,
+                            base::Unretained(drag_drop_client())));
+
+  // It will call ReleaseCapture(), and BaseView will no longer think it's

[tapted, 2016/09/21 10:07:05]

update comment.

[snake, 2016/09/21 12:29:52]

Done.

+  // dragging.
+  drag_drop_client()->StartDragAndDrop(
+      target_, data, 0, ui::DragDropTypes::DRAG_EVENT_SOURCE_MOUSE);
+
+  EXPECT_FALSE(bridge_->HasCapture());
+}
+
 // Tests if the drag and drop target rejects the dropped data with the
 // incorrect format.
 TEST_F(DragDropClientMacTest, InvalidFormatDragDrop) {