This reduces the complexity of our dependency graph.
It also makes sub_store.get parallel to message_store.get.
For both you pass in the relevant id to get the
full validated object.
We extract compose_fade_users and compose_fade_helper.
This is a pretty verbatim extraction of code, apart from adding a few
exports and changing the callers.
This change makes the buddy_data module no longer sit "above" these
files in the dependency graph (at least not via compose_fade):
* jquery
* lodash (not a big deal)
* compose_state
* floating_recipient_bar
* message_viewport
* rows
The new moules have dependencies that buddy_data already
had directly for other reasons:
* people
* util
And then buddy_data still depends on stream_data indirectly through
the compose-fade logic for stream_data. Even without compose-fade, it
would depend indirectly on stream_data via hash_util.
Note that we could have lifted the calls to compose_fade out of
buddy_data to move some dependencies around, but it's useful to have
buddy_data fully encapsulate what goes into the buddy list without
spreading responsibilities to things like activity.js and
buddy_list.js. We can now unit-test the logic at the level of
buddy_data, which is a lot easier than trying to do it via modules
that delegate drawing or do drawing (such as activity.js and
buddy_list.js).
Note that we still don't have 100% line coverage on the
compose_fade.js module, but all the code that we extracted now is
covered, mostly via buddy_data tests.