Tests for undo tree.
Since this script is sourced we need to explicitly break changes up in
undo-able pieces.  Do that by setting 'undolevels'.

STARTTEST
:" Delete three characters and undo
Gx:set ul=100
x:set ul=100
x:.w! test.out
g-:.w >>test.out
g-:.w >>test.out
g-:.w >>test.out
g-:.w >>test.out
:"
:/^111/w >>test.out
:" Delete three other characters and go back in time step by step
$x:set ul=100
x:set ul=100
x:.w >>test.out
:sleep 1
g-:.w >>test.out
g-:.w >>test.out
g-:.w >>test.out
g-:.w >>test.out
g-:.w >>test.out
g-:.w >>test.out
g-:.w >>test.out
g-:.w >>test.out
10g+:.w >>test.out
:"
:/^222/w >>test.out
:" Delay for three seconds and go some seconds forward and backward
:sleep 3
Aa:set ul=100
Ab:set ul=100
Ac:set ul=100
:.w >>test.out
:ear 1s
:.w >>test.out
:ear 3s
:.w >>test.out
:later 1s
:.w >>test.out
:later 1h
:.w >>test.out
:qa!
ENDTEST

1111 -----
2222 -----

123456789