test: add polymorphic lookup tests

they pass on v-11-dev

I'm going to look into the existing lookup warnings

now
```
[POLYMORPHIC TYPE NOT FOUND] No polymorphic types found for fileable
[POLYMORPHIC TYPE] No polymorphic types found for FilePropertiesResource fileable
[POLYMORPHIC TYPE NOT FOUND] No polymorphic types found for respondent
[POLYMORPHIC TYPE] No polymorphic types found for QuestionResource respondent
[POLYMORPHIC TYPE NOT FOUND] No polymorphic types found for respondent
[POLYMORPHIC TYPE] No polymorphic types found for AnswerResource respondent
[POLYMORPHIC TYPE NOT FOUND] No polymorphic types found for keepable
[POLYMORPHIC TYPE] No polymorphic types found for KeeperResource keepable
```

Author: bf4

test/fixtures/active_record.rb

@@ -429,6 +429,18 @@
     t.integer :version
     t.timestamps null: false
   end
+  create_table :contact_media do |t|
+    t.string :name
+    t.references :party, polymorphic: true, index: true
+  end
+
+  create_table :individuals do |t|
+    t.string :name
+  end
+
+  create_table :organizations do |t|
+    t.string :name
+  end
 end
 
 ### MODELS
@@ -624,6 +636,24 @@ class Fact < ActiveRecord::Base
 class Like < ActiveRecord::Base
 end
 
+class TestApplicationRecord < ActiveRecord::Base
+  self.abstract_class = true
+end
+
+class ContactMedium < TestApplicationRecord
+  belongs_to :party, polymorphic: true, inverse_of: :contact_media
+  belongs_to :individual, -> { where( contact_media: { party_type: 'Individual' } ).eager_load( :contact_media ) }, foreign_key: 'party_id'
+  belongs_to :organization, -> { where( contact_media: { party_type: 'Organization' } ).eager_load( :contact_media ) }, foreign_key: 'party_id'
+end
+
+class Individual < TestApplicationRecord
+  has_many :contact_media, as: :party
+end
+
+class Organization < TestApplicationRecord
+  has_many :contact_media, as: :party
+end
+
 class Breed
   include ActiveModel::Model
 
@@ -1227,6 +1257,18 @@ class IndicatorsController < JSONAPI::ResourceController
 class RobotsController < JSONAPI::ResourceController
 end
 
+class IndividualsController < BaseController
+end
+
+class OrganizationsController < BaseController
+end
+
+class ContactMediaController < BaseController
+end
+
+class PartiesController < BaseController
+end
+
 ### RESOURCES
 class BaseResource < JSONAPI::Resource
   abstract
@@ -2685,6 +2727,24 @@ class RobotResource < ::JSONAPI::Resource
   end
 end
 
+class ContactMediumResource < JSONAPI::Resource
+  attribute :name
+  has_one :party, polymorphic: true
+end
+
+class IndividualResource < JSONAPI::Resource
+  attribute :name
+  has_many :contact_media
+end
+
+class OrganizationResource < JSONAPI::Resource
+  attribute :name
+  has_many :contact_media
+end
+
+class PartyResource < JSONAPI::Resource
+end
+
 ### PORO Data - don't do this in a production app
 $breed_data = BreedData.new
 $breed_data.add(Breed.new(0, 'persian'))

test/integration/requests/polymorphic_test.rb

@@ -0,0 +1,83 @@
+require File.expand_path('../../../test_helper', __FILE__)
+
+# copied from https://github.com/cerebris/jsonapi-resources/blob/e60dc7dd2c7fdc85834163a7e706a10a8940a62b/test/integration/requests/polymorphic_test.rb
+# https://github.com/cerebris/jsonapi-resources/compare/bf4_fix_polymorphic_relations_lookup?expand=1
+class PolymorphicTest < ActionDispatch::IntegrationTest
+
+  def json_api_headers
+    {'Accept' => JSONAPI::MEDIA_TYPE, 'CONTENT_TYPE' => JSONAPI::MEDIA_TYPE}
+  end
+
+  def test_find_party_via_contact_medium
+    individual = Individual.create(name: 'test')
+    contact_medium = ContactMedium.create(party: individual, name: 'test contact medium')
+    fetched_party = contact_medium.party
+    assert_same individual, fetched_party, "Expect an individual to have been found via contact medium model's relationship 'party'"
+  end
+
+  def test_get_individual
+    individual = Individual.create(name: 'test')
+    ContactMedium.create(party: individual, name: 'test contact medium')
+    get "/individuals/#{individual.id}"
+    assert_jsonapi_response 200
+  end
+
+  def test_get_party_via_contact_medium
+    individual = Individual.create(name: 'test')
+    contact_medium = ContactMedium.create(party: individual, name: 'test contact medium')
+    get "/contact_media/#{contact_medium.id}/party"
+    assert_jsonapi_response 200, "Expect an individual to have been found via contact medium resource's relationship 'party'"
+  end
+end
+
+# copied from https://github.com/cerebris/jsonapi-resources/pull/1349/files
+# require File.expand_path('../test_helper', __FILE__)
+#
+# Replace this with the code necessary to make your test fail.
+# class BugTest < Minitest::Test
+#   include Rack::Test::Methods
+#
+#   def json_api_headers
+#     {'Accept' => JSONAPI::MEDIA_TYPE, 'CONTENT_TYPE' => JSONAPI::MEDIA_TYPE}
+#   end
+#
+#   def teardown
+#     Individual.delete_all
+#     ContactMedium.delete_all
+#   end
+#
+#   def test_find_party_via_contact_medium
+#     individual = Individual.create(name: 'test')
+#     contact_medium = ContactMedium.create(party: individual, name: 'test contact medium')
+#     fetched_party = contact_medium.party
+#     assert_same individual, fetched_party, "Expect an individual to have been found via contact medium model's relationship 'party'"
+#   end
+#
+#   def test_get_individual
+#     individual = Individual.create(name: 'test')
+#     ContactMedium.create(party: individual, name: 'test contact medium')
+#     get "/individuals/#{individual.id}"
+#     assert_last_response_status 200
+#   end
+#
+#   def test_get_party_via_contact_medium
+#     individual = Individual.create(name: 'test')
+#     contact_medium = ContactMedium.create(party: individual, name: 'test contact medium')
+#     get "/contact_media/#{contact_medium.id}/party"
+#     assert_last_response_status 200, "Expect an individual to have been found via contact medium resource's relationship 'party'"
+#   end
+#
+#   private
+#
+#   def assert_last_response_status(status, failure_reason=nil)
+#     if last_response.status != status
+#       json_response = JSON.parse(last_response.body) rescue last_response.body
+#       pp json_response
+#     end
+#     assert_equal status, last_response.status, failure_reason
+#   end
+#
+#   def app
+#     Rails.application
+#   end
+# end

test/test_helper.rb

@@ -414,6 +414,9 @@ class CatResource < JSONAPI::Resource
   jsonapi_resources :widgets, only: [:index]
   jsonapi_resources :indicators, only: [:index]
   jsonapi_resources :robots, only: [:index]
+  jsonapi_resources :contact_media
+  jsonapi_resources :individuals
+  jsonapi_resources :organizations
 
   mount MyEngine::Engine => "/boomshaka", as: :my_engine
   mount ApiV2Engine::Engine => "/api_v2", as: :api_v2_engine