How do you test an AJAX request with RSpec/RoR?

If you're talking about testing it inside your controller specs, where you normally call

get :index

to make an HTTP request to the index action, you would instead call

xhr :get, :index

to make an XmlHttpRequest (AJAX) request to the index action using GET.

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Rails 5 / 6

Since Rails 5.0 (with RSpec 3.X), try setting xhr: true like this:

get :index, xhr: true

Background

Here's the relevant code in the ActionController::TestCase. Setting the xhr flag ends up adding the following headers:

if xhr
  @request.set_header "HTTP_X_REQUESTED_WITH", "XMLHttpRequest"
  @request.fetch_header("HTTP_ACCEPT") do |k|
    @request.set_header k, [Mime[:js], Mime[:html], Mime[:xml], "text/xml", "*/*"].join(", ")
  end
end

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Syntax changed a bit for Rails 5 and rspec > 3.1(i believe)

for POST requests:

post :create, xhr: true, params: { polls: { question: 'some' } }

you now need explicitely set params

for GET requests:

get :action, xhr: true, params: { id: 10 }

for rails 4 and rspec <= 3.1

xhr post :create, { polls: { question: 'some' } }

GET requests:

xhr get :show, id: 10

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Here is a full example:

get "/events", xhr: true, params: { direction: "past" }

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