Some files already were using `noop` in place of `() => {}`.
It's both clearer what it means and is easier to type.
This updates all test files to fully use `noop`, and
adds a shared import from the test lib file.
Since is_visible was refactored to use a variable, these mocks
are not required.
Also, since is_visible return `false` by default, mocking it
to return false is not required.
This should cause no functional changes.
This is part of a multi-step effort to move away
from using stream names to reference streams, now
that it's impossible for a user to write a message
with an invalid stream name (since switching to
the dropdown).
This function will allow us to adjust the codebase to write what it
means semantically -- whether a check is for the message list being
visibly empty, or completely empty.
In this commit, we leave the .empty() method incorrect, because
several other adjustments need to be made atomically with fixing it.
This lets us simplify the long-ish ‘../../static/js’ paths, and will
remove the need for the ‘zrequire’ wrapper.
Signed-off-by: Anders Kaseorg <anders@zulip.com>