be false vs be_falsey in rspec [duplicate]

Question

I know be false will just return true if the expected value is a pure false value, wherease be_falsey will return true if the expected value is either false or nil.

However, I fail to understand when would I use one or the other. I fail to see an example where be_falsey would be more useful than be false.

Answer 1

There are lots of situations in Ruby where you get a nil result and want to treat it like false. For example, suppose we have a method that handles an options hash, and we want the absence of an option to be the same as the option set to false:

def verbose?(opts)
  opts[:verbose]  
end

opts = { verbose: false }
expect(verbose?(opts)).to be_falsey # => PASS

opts = { verbose: true }
expect(verbose?(opts)).to be_falsey # => FAIL

opts = {}
expect(verbose?(opts)).to be_falsey # => PASS

Obviously this is a simplistic example (you could argue that verbose? should always return true or false), but similar scenarios are common in Ruby.