How to test monkey-patch methods?

I won't explain what's Monkey-patch, many developers knew about it.

In Ruby, we can create and test monkey-patch methods like the code below:

    module StringExtensions
      # Number of words in a string
      def word_count
        self.split.size
      end
    end
  
    describe String do
      before do
        String.include StringExtensions
      end
  
      describe "#word_count" do
        it "returns number of words in a string" do
          expect("Hell yeah".word_count).to eq 2
          expect("Hello world! I'm Vincent".word_count).to eq 4
        end
  
        it "returns zero if a string is empty" do
          expect("".word_count).to eq 4
        end
      end
    end
  

Personally, I don't like monkey-patch, we can create a Word class for methods relate to words in a string. But you know, sometimes we have to monkey-path so this is one way we can apply.

Thanks for reading!