Testing JSON API in Rails 3.2 using rspec using exact PUT/POST bodies as Backbone would send

Question

I'm trying to write a set of rspec tests for a JSON API written in Rails 3.2 with Backbone as the front end. The tests I'm writing are specifically for the Rails controllers.

Now, the application itself is working fine. When a client issues a PUT request with the body:

{
  "id":1,
  "name":"updated product set",
  ...
}

Everything is great. In the background Rails will take that body, then transform it into:

{
  "id":1,
  "name":"updated product set",
  ...
  "model_name" => { ... }
}

where the hash "model_name" points to contains the attribute values it can automatically figure out from the input. All is well.

When I try the same exact request from the testing environment, all is not well. If I create a hash that is exactly the same PUT body hash as above, but in rspec:

@update_json = {
  "id":1,
  "name":"updated product set",
  ...
}
header "Accept","application/json"
header "Content-type","application/json"
put :update, @update_json

Things do not work out at all. In the controller, if I inspect the params variable I get:

{ "model_name" => {} }

If I omit the "Content-type" header line, I get instead @update_json, but without the Rails manipulation that creates the "model_name" mapping which I require in my controller.

The only way I've gotten a successful test to run is the following:

@update_json = {
  :format => "json",
  "id":1,
  "model_name" => {
      "id":1,
      "name":"updated product set",
      ...
  }
}
header "Accept","application/json"
put :update, @update_json

However, this is not a real-world test since it's not testing the exact PUT body that would be sent by my backbone front-end.

Any ideas?

UPDATE: From looking around it looks like you can't actually do a real HTTP request from rspec; it's just mocked up. For example, you can't get the system to respond with a 404 since Rails throws an Exception that would normally be caught by Rails network stack and turned into a 404 but which isn't with Rspec. So the problem looks deeper than what's above...

Franck Verrot · Answer 1 · 2012-11-11T08:34:55.320

1

Can you try this?

@update_json = {
  "id":1,
  "model_name" => {
      "id":1,
      "name":"updated product set",
      ...
  }
}
put :update, @update_json, :format => :json

Edit (11/11/12):

Have you tried to instantiate the request manually and see what happens?

Weird. Have you tried to go the "plain Ruby way"?

env = Rack::MockRequest.env_for('/posts/1', :method => 'PUT', <some other params>)
status, headers, body = PostsController.action(:update).call(env)
...

edited Nov 11 '12 at 08:34

answered Nov 03 '12 at 07:02

Franck Verrot

1,041
7
9

Cesario: yeah. Same problem as above. I believe the fundamental issue is that this style of integration testing is impossible from within rspec since it doesn't go through Rack the same way an external request does. – Rob Gonzalez Nov 03 '12 at 16:55
Updating the answer, putting inline code in here is a PITA :) – Franck Verrot Nov 11 '12 at 08:30
Cesario: I have not tried that, but it's a good thought. However, doesn't the put/get/etc. rspec vocabulary use the MockRequest underneath? I suspect that it's the same problem, which is to say that the Rack::MockRequest avoids the network stack. Will give it a shot and see if I see anything different. – Rob Gonzalez Nov 11 '12 at 14:34

toadjamb · Accepted Answer · 2013-01-25T06:30:51.867

I was having the same problem. No matter what I did, or which ways I specified the content type as 'application/json', it just wouldn't work. If there was a suggestion on the internet for setting the content type to json, I tried it. I even tried them all together at the same time.

Ultimately, I traced it to ActionController::ParamsWrapper, where _wrapper_enabled? was always returning false (due to request.content_mime_type being nil). This solution works for me. I was looking for the 'magical' params key to get added as well and this does it.

mime_type = mock
mime_type.stub :ref => :json
request.stub :content_mime_type => mime_type
request.accept = 'application/json'
post :create, widget.as_json

The values are:

widget.as_json #=> {
  "created_at"=>nil,
  "description"=>"Description 1 - Quidem nihil quae aliquid sed qui.",
  "id"=>nil,
  "order"=>1,
  "title"=>"Title 1 - ut",
  "updated_at"=>nil
}

# params hash in the controller.
params #=> {
  "created_at"=>nil,
  "description"=>"Description 1 - Quidem nihil quae aliquid sed qui.",
  "id"=>nil,
  "order"=>"1",
  "title"=>"Title 1 - ut",
  "updated_at"=>nil,
  "controller"=>"api/widgets",
  "action"=>"create",
  "widget"=>{
    "title"=>"Title 1 - ut",
    "order"=>"1",
    "description"=>"Description 1 - Quidem nihil quae aliquid sed qui."
  }
}

This is exactly what I wanted. Only title, order, and description are set as attr_accessible, hence the only attributes that appear in the magically created :widget hash.

I am also using active_model_serializers, so the as_json is running through that, in case anyone thinks it matters.

This is part of a public example app I'm building, so this code will be able to be seen in use, if anyone thinks it might be useful.

This works, and is MUCH better than the hacked up wrap_params test method that we created :) Thanks!! — Rob Gonzalez, Feb 04 '13 at 14:49

score 1 · Answer 3 · answered Feb 13 '14 at 16:36

Looks like the ability to do post :update, '{"some": "json"}' was added to the internal ActionPack test_case.rb used by rspec in this commit: https://github.com/rails/rails/commit/5b9708840f4cc1d5414c64be43c5fc6b51d4ecbf

So, other options could be to upgrade to Rails 4 and things will work as expected, or to integrate the above commit.

Testing JSON API in Rails 3.2 using rspec using exact PUT/POST bodies as Backbone would send

3 Answers3

Linked