run routine f with a keyboard channel containing #\a and a fake screen
check that fake screen contains 'a' at (5, 5)
---
; At its core, an editor is a 2D array of characters and a cursor.
given [
editor 5 5
]
Cursor should be at (0 0)
now [
type "abc"
]
Cursor should be at (0 3)
"abc" should be at (0 0)
Trace should contain [
typed "a"
typed "b"
typed "c"
]