Catch argumentless matchers in RSpec/ExpectActual

[cvx]

Flags e.g. expect(".foo").to be_present and expect(1).to be.

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Before submitting the PR make sure the following are checked:

• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Updated documentation.
• Added an entry to the CHANGELOG.md if the new code introduces user-observable changes.
• The build (bundle exec rake) passes (be sure to run this locally, since it may produce updated documentation that you will need to commit).

[cvx]

This case wasn't supported only to simplify implementation afaict (see #858)

[bquorning]

Thank you for the PR, I think it will be a useful addition. I have added a few comments.

Also, I would prefer if the first commit was extracting the method #register_offense (without next if expected.nil?) so that the 2nd commit clearly shows what the actual change is.

[cvx]

All done!

[bquorning]

@cvx Could I ask you to rebase on top of the latest master branch please?

[cvx]

Done!

[pirj]

Are there real life examples of this?
How those offences would be handled by the user?

[bquorning]

My guess is that offenses would reveal typos, where people are testing literals instead of variables. E.g. they would change expect(5).to be_odd to expect(foo).to be_odd.