When visiting a user profile, and then opening the search, there's an option to filter down by posts made by that user.
When clicking that option, it used to pre-fill the "search bar" with "@<username>" to filter down the search.
This restore this behaviour and add a system spec to ensure it doesn't regress.
Context - https://meta.discourse.org/t/in-posts-by-search-option-does-not-work-when-clicked/312916
What is the problem?
We are relying on RSpec custom matchers in system tests by defining
predicates in page objects. The problem is that this can result in a
system test unnecessarily waiting up till the full duration of
Capybara's default wait time when the RSpec custom matcher is used with
`not_to`. Considering this topic page object where we have a `has_post?`
predicate defined.
```
class Topic < PageObject
def has_post?
has_css?('something')
end
end
```
The assertion `expect(Topic.new).not_to have_post` will end up waiting
the full Capybara's default wait time since the RSpec custom matcher is
calling Capybara's `has_css?` method which will wait until the selector
appear. If the selector has already disappeared by the time the
assertion is called, we end up waiting for something that will never
exists.
This commit fixes such cases by introducing new predicates that uses
the `has_no_*` versions of Capybara's node matchers.
For future reference, `to have_css` and `not_to have_css` is safe to sue
because the RSpec matcher defined by Capbyara is smart enough to call
`has_css?` or `has_no_css?` based on the expectation of the assertion.
Fixes an issue on mobile where navigating away from search and returning
results in confusing UI where there are no results but headings says "N
results found".
