It is perfectly fine and expected to detach from the screen just by
the UI disconnecting from nvim or exiting nvim. Just keep detach() in
screen_basic_spec, to get some coverage of the detach method itself.
This avoids hang on failure in many situations (though one could argue
that detach() should be "fast", or at least "as fast as resize",
which works in press-return already).
Never use detach() just to change the size of the screen, try_resize()
method exists for that specifically.
Hope this will make people using feed_command less likely: this hides bugs.
Already found at least two:
1. msgpackparse() will show internal error: hash_add() in case of duplicate
keys, though it will still work correctly. Currently silenced.
2. ttimeoutlen was spelled incorrectly, resulting in option not being set when
expected. Test was still functioning somehow though. Currently fixed.
It is otherwise impossible to determine which test failed sanitizer/valgrind
check. test/functional/helpers.lua module return was changed so that tests which
do not provide after_each function to get new check will automatically fail.
