Unfortunately, I have to defer implementation of this due to triage, but I have the rough concept for a unit test for #9802 in mind.

Ideal TWo-caps prevention test:

Within gesture-recognizer's headless-testing section...

Setup

• configuration's itemIdentifier function:
  • if state token 'default', output lowercase
  • if state token 'shift', output uppercase
  • first touch's coordinates => 'a' / 'A', depending on state token (as above)
  • second touch's coordinates => 'b' / 'B', depending on state token
• the gesture-recognizer instance should start with the state token set as 'default'

Test

• emulate LITERALLY simultaneous touches
  • two contact points; ensure both last around 40 ms and then release.
    • The coordinates should match those expected by itemIdentifier as mentioned above.
  • The InputSequenceSimulator unit test resource should already be well-positioned for simulating this in a unit test.
• listen for sequences (recognizedGesture event)
  • first one:
    • verify expected output (lowercase) (either 'a' or 'b')
    • have handler for first sequence's 'stage' event set the recognizer's state token to 'shift'
  • second one:
    • verify expected output (uppercase) (either 'A' or 'B')