We add a padded div to our container for the buddy
list to give scrolling the illusion that we've
rendered every list item, while still letting
the browser do the heavy lifting instead of trying
to fake it out too much.
This new div allows us to split out two concerns:
semantic list of items - remains in #user_presences
widget real estate - controlled by new #buddy_list_wrapper
We will use this for progressive rendering. We want to add
padding to the buddy list without messing with the integrity
of the actual HTML '<ul>' list. (One ugly alternative would
have been to add a dummy list item, which be a pitfall for
any code traversing the list.)
Basically, all the code relating to click handlers and similar
things was left alone. We only change js/css related to
scrolling, resizing, and overflow.
This version of progressive scrolling lazily
renders buddy list items, but it doesn't
provide the browser with any notion of upcoming
list items, so as you scroll down and the size
of the rendered list grows, the scrollbar shows
you being too close to the bottom.
This maintains 100% coverage on buddy_list.js.
We were passing this in before, but having it as
a data member reinforces the idea that we'll want
this to be a first-class concept in the list, since
we depend on ordering for various things.
This run_test helper sets up a convention that allows
us to give really short tracebacks for errors, and
eventually we can have more control over running
individual tests. (The latter goal has some
complications, since we often intentionally leak
setup in tests.)
Steve Howell