[Scheduler] Add tests for isInputPending (#22140)
[Scheduler] Add tests for isInputPending (#22140)

This feature was already implemented but we didn't have any tests. So
I wrote some.
camsong/react,camsong/react,camsong/react,yungsters/react,facebook/react,facebook/react,facebook/react,camsong/react,yungsters/react,camsong/react,facebook/react,yungsters/react,yungsters/react,camsong/react,yungsters/react,facebook/react,yungsters/react,facebook/react,facebook/react,yungsters/react,camsong/react