be with a block is deceptive

[pirj]

Subject of the issue

    expect([-1,2,3]).to all be(&:positive?)

Found in rubocop/rubocop-rspec#919

Expected behavior

A warning or an error makes it obvious that be doesn't accept a block.

Actual behavior

  is expected to all be

1 example, 0 failures
```

[JonRowe]

There are a lot of places where we don't check for a block and issue a warning, we've generally not subscribed to the philosophy of warning about Rubyisms, in Ruby you can give a block to almost any method and it'll be ignored if its not expected...

[JonRowe]

e.g.

"1".to_i { |x| raise x }
# => 1

[pirj]

Agree, there are a lot more cases than just be. rubocop/rubocop#7798

I guess it's a good job for RuboCop RSpec.