In Rails, how do you functional test a Javascript response format?

Question

If your controller action looks like this:

respond_to do |format|
  format.html { raise \'Unsupported\' }
  format.js # index.js.erb
end

and yo

Answer 1

I had similar problem:

# controller
def create
  respond_to do |format|
    format.js
  end
end

# test

test "call format js" do
  record = promos(:one)
  post some_url(record)
  assert true
end

and the result was this:

> rails test
Error:
ActionController::UnknownFormat: ActionController::UnknownFormat

I fixed it with this adjusting to the test(adding headers):

test "call format js" do
  record = promos(:one)
  headers = { "accept" => "text/javascript" }
  post some_url(record), headers: headers
  assert true
end

rails (6.0.0.beta3)