This patch should ideally be split into multiple smaller ones, but life
is life.
This main purpose of this patch is to fix and to test
`SlidingSyncListRequestGenerator`. This quest has led me to rename
mutiple fields in `SlidingSyncList` and `SlidingSyncListBuilder`, like:
* `rooms_count` becomes `maximum_number_of_rooms`, it's not something
the _client_ counts, but it's a maximum number given by the server,
* `batch_size` becomes `full_sync_batch_size`, so that now, it
emphasizes that it's about full-sync only,
* `limit` becomes `full_sync_maximum_number_of_rooms_to_fetch`, so that
now, it also emphasizes that it's about ful-sync only _and_ what the
limit is about!
This quest has continued with the renaming of the `SlidingSyncMode`
variants. After a discussion with the ElementX team, we've agreed on the
following renamings:
* `Cold` becomes `NotLoaded`,
* `Preload` becomes `Preloaded`,
* `CatchingUp` becomes `PartiallyLoaded`,
* `Live` becomes `FullyLoaded`.
Finally, _le plat de résistance_.
In `SlidingSyncListRequestGenerator`, the `make_request_for_ranges`
has been renamed to `build_request` and no longer takes a `&mut self`
but a simpler `&self`! It didn't make sense to me that something
that make/build a request was modifying `Self`. Because the type of
`SlidingSyncListRequestGenerator::ranges` has changed, all ranges now
have a consistent type (within this module at least). Consequently, this
method no longer need to do a type conversion.
Still on the same type, the `update_state` method is much more
documented, and errors on range bounds (offset by 1) are now all fixed.
The creation of new ranges happens in a new dedicated pure function,
`create_range`. It returns an `Option` because it's possible to not be
able to compute a range (previously, invalid ranges were considered
valid). It's used in the `Iterator` implementation. This `Iterator`
implementation contains a liiiittle bit more code, but at least now
we understand what it does, and it's clear what `range_start` and
`desired_size` we calculate. By the way, the `prefetch_request` method
has been removed: it's not a prefetch, it's a regular request; it was
calculating the range. But now there is `create_range`, and since it's
pure, we can unit test it!
_Pour le dessert_, this patch adds multiple tests. It is now
possible because of the previous refactoring. First off, we test the
`create_range` in many configurations. It's pretty clear to understand,
and since it's core to `SlidingSyncListRequestGenerator`, I'm pretty
happy with how it ends. Second, we test paging-, growing- and selective-
mode with a new macro: `assert_request_and_response`, which allows to
“send” requests, and to “receive” responses. The design of `SlidingSync`
allows to mimic requests and responses, that's great. We don't really
care about the responses here, but we care about the requests' `ranges`,
and the `SlidingSyncList.state` after a response is received. It also
helps to see how ranges behaves when the state is `PartiallyLoaded`
or `FullyLoaded`.
So far, the `SlidingSync.pos` field was public to the crate. In order to avoid
breaking the internal state of this type, its visibility is now private.
However, we need to be able to change the value when testing the
`SlidingSync` type itself. To achieve that, this patch removes the old
`force_sliding_sync_pos` function, and implements 2 new functions: `set_pos`
and `pos` directly on `SlidingSync` only when `#[cfg(any(test, feature ="testing"))]`.
