const scrollableSize = 100.0;
final offsetManual = Offset(180, 400);
final offset = Offset(0.0, -scrollableSize); // page turns blank
await tester.dragFrom(offsetManual, offset);

I was trying this in Flutter test. With this dragFrom, move upwards (0, 100), left (-100, 0), and right (100, 0) are all working. But whenever I try to move down (0, -100), the screen would simply turn blank. I can drag up to move down without any problem when I run flutter run to test myself.

Can someone let me know what can be the reason of this? The same test file had been tried in another repo and it works perfectly there.