In `RoomList::entries_with_dynamic_adapters`, we were using the
`Limit::dynamic` constructor. It builds a `Limit` stream adapter where
the limits come from a `Stream`. The immediate impact is that this
constructor does only return a new `Stream`, but it cannot return
the initial items of the vector. Thus, it wasn't possible to reset
the final `Stream` with a `VectorDiff::Reset { values }`. Instead, we
were emitting a `Clear` (from this code) then a `Append` (from the
`Limit` stream). Sadly, for some client apps, like Element X iOS, these
2 diffs (`Clear` and `Append`) result in a “rendering blink”.
Hopefully for us, now there is new constructors for `Limit`! One of them
is `Limit::dynamic_with_initial_limit`, which returns the initial items
along with the new `Stream`. That's perfect, we can reset the final
`Stream` with `Reset { values }` again, thus removing the “UI blinking”
effect in Element X iOS.
This patch switches `Limit::dynamic` to
`Limit::dynamic_with_initial_limit`, and updates/simplifies the tests
accordingly.
Ivan Enderlin
0f7e5ba4b0