$ rubocop
Inspecting 2 files
.C

Offenses:

    test.rb:5:7: C: [Correctable] Style/HashSyntax: Explicit the hash value.
    { foo:, bar: }
      ^^^
test.rb:5:13: C: [Correctable] Style/HashSyntax: Explicit the hash value.
    { foo:, bar: }
            ^^^

2 files inspected, 2 offenses detected, 2 offenses autocorrectable