Question

I have a markdown helper that looks like this in application_helper.rb.

How would you go about writing a test for something like this? Also, is this the best way to generate simple HTML from markdown?

Thanks!

def markdown(text)
  Redcarpet::Markdown.new(Redcarpet::Render::HTML, :autolink => true, :space_after_headers => true).render(text).html_safe
end

Answer 1

Two options come to mind:

1. Stub out Redcarpet::Markdown and create an expectation of what it should receive:

   expect(Redcarpet::Markdown).to receive(:new).with(...) # `with` args omitted for brevity
   markdown(text)
   

   The problem here is that the coupling between the method and the test is very high. It’s very difficult to refactor the method without breaking the test, even though the method actually functions the same.

2. Assert the correctness of the output text directly:

   expect(markdown(text)).to eq 'This is markdownified'
   

   This allows you to refactor better, but it seems more like an integration test, not a unit test, and is almost testing Redcarpet more than your own method. Unit tests should usually assume that the external methods they call work correctly.

This is one of those cases where testing feels redundant to me since the method is just a thin wrapper around another, and I would not be against not unit testing it, and rather ensuring that you have an integration test—if this is by having your spec be an integration test, then that’s probably okay.

It’s ultimately all up to you and your TDD workflow and overall testing principles though.