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Sending JSON in functional tests does not populate the params hash #13135

haihappen opened this Issue · 28 comments
test 'sending raw JSON does not populate the params hash' do
  @request.headers['Content-Type'] = 'application/json'
  post :create, { key: "value" }.to_json

  assert_equal "value", params['key'] # => Will fail!

will result in following params hash:

{"controller"=>"posts", "action"=>"create"} # Hence the missing key-value pair.

However sending the corresponding request with curl or other apps, it works like intended. I even asked on StackOverflow, however no answer yet. Looks like a bug for me.

Ruby on Rails member

Hi @haihappen, you specified the Content-Type: application/json header in your curl command but you don't have this in your test, so that's might be why it's not working.


I did it with @request.headers['Content-Type'] = 'application/json'and by passing the format: :json option, both didn't work. Btw updated the issue and added the header.

Ruby on Rails member

In a functional test there's no middleware stack - everything is mocked and the controller action is called directly. Just pass the parameters hash you want to test without converting it to JSON first.

@pixeltrix pixeltrix closed this

Ok, the only problem is:

I have a before_filter which checks for a Signature based on the raw request body, much like the same technique used by AWS. What is the best way to test this before_filter, just rely on integration tests and skip it in functional tests or populating the params hash on my own (like I'm already doing).

Ruby on Rails member

This is a bit of a hack but if you pass a string like you were doing then this is set to the raw request, however you still need to pass the parameters, e.g

form = { post: { title: 'A post title', body: 'Some text' } }
post :create, form.to_json, form.merge(format: 'json')

The format: 'json' ensures that the request is set to the correct format and before filters should still run even in functional tests. I need to check whether this broke during the Rails 2.3 -> 3.0 upgrade - we switched to parsing parameters using rack middleware and it may have not been tested properly.

@pixeltrix pixeltrix reopened this
@pixeltrix pixeltrix was assigned
Ruby on Rails member

So it appears that passing a body as a string was added in 5b97088 but the documentation is poor since the example has no assertions and the tests don't check for the request body being parsed. I'll take a look to see if it can be made to work - it's a little tricky as it needs to merge with anything passed afterwards.


The problem here is a fundamental design flaw, @pixeltrix.

If we'd actually invoke the Rails stack from top to bottom, we could make sure the environment is the same as in production. Also, this would save hundreds of LOCs in AC::TestCase where we manually set up an error-prone fake environment for the test.

Currently, this would imply creating a real HTTP request and invoking the stack.


By "invoking the stack" I mean running the entire thing including Rack middlewares - which would automatically parse the request body into params.

Also, we've had severe problems in Roar where the API (!) for TestRequest would differ from a "real" Rack::Request instance (e.g. body.string).

Things would be easier and closer to real life by running the stack. What do you think?

Ruby on Rails member

@apotonick yeah, I know about the full stack thing - I'm always having to explain that to people. The reason for the mock environment is speed - currently running a simple controller test using AC::TestCase is 25% quicker than using AD::IntegrationTest. My not-so secret plan is to make integration tests at least 25% quicker, make AC::TestCase inherit from AD::IntegrationTest, add a legacy DSL module to handle the test API and then nuke the current functionals code. Not going to happen for 4.1 but I'm definitely planning on it for 4.2.

Can you make this work using the currently flawed code? :smile:


Awesome, @pixeltrix, I'm all up for the secret battle plan. In the mean-time I can fix this bug. I look into it tomorrow!

How do you measure speed for functional/integration test?

Ruby on Rails member

How do you measure speed for functional/integration test?

Just implement the equivalent test in a functional test and integration test and then benchmark it in the normal way, e.g:

require 'benchmark/ips'
require "action_controller/railtie"

class BlogApplication < Rails::Application
  config.eager_load = false
  config.root = File.dirname(__FILE__)
  config.session_store :cookie_store, key: 'session'
  config.secret_key_base = 'secret'


BlogApplication.routes.draw do
  resources :posts, only: %w[index]

require 'rails/test_help'

class PostsController < ActionController::Base
  def index
    render text: 'Hello, World!'

class FunctionalTest < ActionController::TestCase
  tests PostsController

  def test_posts_index
    get :index
    assert_equal 'Hello, World!', response.body

class IntegrationTest < ActionDispatch::IntegrationTest
  def test_posts_index
    get '/posts'
    assert_equal 'Hello, World!', response.body

Benchmark.ips do |x|
  runner =
  functional ='test_posts_index')
  integration ='test_posts_index')'Functional Test') do
  end'Integration Test') do

Which when I run it on my MacBook Air gives:

$ ruby test_comparison.rb 
Calculating -------------------------------------
     Functional Test        97 i/100ms
    Integration Test        62 i/100ms
     Functional Test     1000.4 (±6.4%) i/s -       5044 in   5.062338s
    Integration Test      624.5 (±4.2%) i/s -       3162 in   5.072164s
Run options: --seed 56593

# Running tests:


Finished tests in 0.017042s, 117.3571 tests/s, 234.7142 assertions/s.

2 tests, 4 assertions, 0 failures, 0 errors, 0 skips

Looking at it again it's more like 33% slower (or functionals are 50% quicker, if you prefer).

@apotonick apotonick added a commit to apotonick/rails that referenced this issue
@apotonick apotonick In AC::TestCase#process, parse the request body to params as it is do…
…ne in the ParamsParser middleware. fixes #13135.

this is another work-around to make AC::TestCase behave the way a real integration test works. as stated here rails#13135 we are planning to replace AC::TestCase logic with a faster IntegrationTest. instead of mocking all the environment variables, this will invoke the Rails stack and provide an environment that's identical to one in production.

@pixeltrix I fixed it in apotonick@1c38716 but this only works for format: :json environments (which should be ok for now).

@haihappen Could you test if that works for you?

Next step: speeding up IntegrationTest - this AC::TestCase is just messy.


@haihappen Hey brother, any news? Is that working for you?

@pixeltrix I can rebase and PR.


@apotonick I changed the particular tests to descend from ActionDispatch::IntegrationTest which fixed the problem for me :)


@haihappen And, is it "slower"? Haha

@pixeltrix Should we merge this anyway? I will focus on making the integration tests faster over xmas.

@apotonick apotonick referenced this issue in apotonick/roar-rails

Sending JSON data in rspec #36

Ruby on Rails member

I'm going to push this to 4.2 - it's going to be hard enough to make sure we don't break people's existing tests without adding more hacks on top so I think it should be done as part of the refactoring

@rafaelfranca rafaelfranca modified the milestone: 4.2.0, 5.0.0

Hey folks. I've spent four hours or so today figuring out what was going on with my controller test, until I reached this page and learnt it was a Rails bug… I don't know how the process works, but maybe it'd be appropiate to add a note at the docs about this? Passing params as JSON is quite common, and unless you dig a lot it's not obvious to learn that in Integration tests you can pass JSON with no problem, but not in Functional tests… Well, this is just an idea to help future folks like me :-)


We also had this problem. If it can be highlighted somewhere in the docs that would've been great

@rails-bot rails-bot added the stale label

This issue has been automatically marked as stale because it has not been commented on for at least
three months.

The resources of the Rails team are limited, and so we are asking for your help.

If you can still reproduce this error on the 4-2-stable, 4-1-stable branches or on master,
please reply with all of the information you have about it in order to keep the issue open.

Thank you for all your contributions.


Can still reproduce on rails 4.2

@rafaelfranca rafaelfranca added pinned and removed stale labels

Yep still present, no easy way to work with raw body in 4.2

Ruby on Rails member

It was fixed on the master branch. Unfortunately it is not easy to backport so it will not be fixed on Rails 4


I've spent about 16 hours trying to figure out why my test wasn't working, and now I'm finally finding this thread and it all makes sense.

In our case, we're using rails-api. Rather than inherit from IntegrationTest, we're just passing a non-JSON hash, and it seems to work.

It's a hideous workaround for an API, but it's faster and we can't wait until Rails 5.

For google purposes so others can find this thread:

strong parameters
rails 4
top level nested key
json minitest
empty parameters
empty params


I started to test with Rack-test. It is a million times faster, no magic and does exactly what you would think it does.


Nice. :+1: Personally, I want to move to RSpec. I miss it. :smile:

Ruby on Rails member

@apotonick yes, you're right - if only it'd been around when integration tests were implemented in Rail 1.1 :wink:


Haha I hear ya @pixeltrix but I still wonder why it never got cleaned up? It's so much code to do a very simple thing. What's the plan with this?

Ruby on Rails member

It is already being done in master branch

@rafaelfranca rafaelfranca modified the milestone: 5.0.0 [temp], 5.0.0
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