JSON Test Serialization on DELETE endpoints Regression in 5.1.4

[brandonhilkert]

Steps to reproduce

We tried to update to 5.1.4 and 2 tests broke because of the following...

Test app: https://github.com/brandonhilkert/bulk-destroy-test

Delete endpoints with supplied a supplied JSON payload are double serialized when using as: :json in the test.

I added a bulk endpoint here: brandonhilkert/bulk-destroy-test@4cfb003

Expected behavior

Test should pass

Actual behavior

Test:

  test "deletes all posts with ID" do
    assert_difference('Post.count', -1) do
      delete bulk_posts_url,
        params: { ids: [posts(:one).id, posts(:two).id] },
        as:     :json
    end
  end

(byebug) params
<ActionController::Parameters {"{\"ids\":"=>{"980190962,298486374"=>{"}"=>nil}}, "format"=>:json, "controller"=>"posts", "action"=>"bulk", "post"=>{}} permitted: false>

Removing as: :json causes the params to be properly serialized and test passes:

  test "deletes all posts with ID" do
    assert_difference('Post.count', -1) do
      delete bulk_posts_url,
        params: { ids: [posts(:one).id, posts(:two).id] }
    end
  end

(byebug) params
<ActionController::Parameters {"ids"=>["980190962", "298486374"], "format"=>:json, "controller"=>"posts", "action"=>"bulk"} permitted: false>

System configuration

Rails version: 5.1.4

Ruby version: 2.4.1p111

[phedkvist]

I believe you meant to put -2 in assert_difference. If I remove as: :json I get an error using destroy_all, I use posts.each(&:destroy) which passes the test. Regardless I get the same behaviour using as: :json.

[brandonhilkert]

destroy vs. destroy_all should make no different. You're right, it should be -2. I've changed it per your suggestions and the test still fails with as: :json and passes when as: :json is removed.

ref: brandonhilkert/bulk-destroy-test@edf9aaa

[morgoth]

We have the same problem with 5.1.4.
We're not using as: :json, but set custom request headers like:

{
  "CONTENT_TYPE" => "application/json",
  "HTTP_ACCEPT" => "application/json"
}

[morgoth]

@brandonhilkert I found that this is caused by a change in rack-test rack/rack-test#200 which was released in 0.7.0. You can verify it by using Rails 5.1.4 and rack-test 0.6.3

Rails allows 0.7.0 since #29859

[rails-bot]

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 5-1-stable branch 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.

[morgoth]

The issue is still present in the rack-test gem, that's still causing a regression in Rails

[y-yagi]

Perhaps this issue will be solved with rack/rack-test#223.

[perlun]

@y-yagi @morgoth I just released rack-test 1.0.0 (yeah, 🎉) - please let me know if the problem persists.

[y-yagi]

Awesome 🎉
I have confirmed that original issue fixed with rack-test 1.0.0.
So I close this. But if anyone still has problem, please reopen it freely. Thanks!