How to set request headers in rspec request spec?

You should be able to specify HTTP headers as the third argument to your get() method as described here:

http://api.rubyonrails.org/classes/ActionDispatch/Integration/RequestHelpers.html#method-i-get

and here

http://api.rubyonrails.org/classes/ActionDispatch/Integration/Session.html#method-i-process

So, you can try something like this:

get '/my/path', nil, {'HTTP_ACCEPT' => "application/json"}

I used this in Test::Unit:

@request.env['HTTP_ACCEPT'] = "*/*, application/youtube-client"
get :index

I'm adding this here, as I got majorly stuck trying to do this in Rails 5.1.rc1

The get method signature is slightly different now.

You need to specify the options after the path as keyword arguments, i.e.

get /some/path, headers: {'ACCEPT' => 'application/json'}

FYI, the full set of keywords arguments are:

params: {}, headers: {}, env: {}, xhr: false, as: :symbol

This is working for controller specs, not request specs:

request.headers["My Header"] = "something"

Using rspec with Rack::Test::Methods

header 'X_YOUR_HEADER_VAR', 'val'
get '/path'

The header var will come through as X-Your-Header-Var

I have to set up headers separately

request.headers["Accept"] = "application/json"

Trying sending it via get/delete/.... is complete garbage in rails4 and causing pain in my head because it is never send as header but as parameter.

{"Accept" => "application/json"}

With RSpec 3 you can use the following syntax

get my_resource_path, params: {}, headers: { 'HTTP_ACCEPT' => "application/json" }

As described in the official Rspec documentation (the link points to v3.7)

To send both xhr: true and headers, I had to do e.g.:

my_headers = { "HTTP_ACCEPT": "application/json" }
get my_path, xhr: true, headers: my_headers

Your question was already answered but in case you want to POST something to another action you have to do this:

post :save, {format: :json, application: {param1: "test", param2: "test"}}

Try something like:

get :index, :format => 'json'