Set up GitHub actions CI (#2403)

* Set up GitHub actions CI
* Remove simplecov entirely for now
* Fix deprecations
* Relax dev deps
* Address Rails 6.0 blocking hosts
* Rails 6.1 content type changed to application/json; charset=utf-8
* Test a few more rubies and rails
* Stop testing grape. We should drop grape support

```
/home/runner/work/active_model_serializers/active_model_serializers/vendor/bundle/ruby/2.6.0/gems/grape-0.19.0/lib/grape/error_formatter.rb:16: warning: in `formatters': the last argument was passed as a single Hash
/home/runner/work/active_model_serializers/active_model_serializers/vendor/bundle/ruby/2.6.0/gems/grape-0.19.0/lib/grape/error_formatter.rb:21: warning: although a splat keyword arguments here
Run options: --seed 23470

..........................................................................................................................................................................................................................................................................................................................................................................................................................................E

ActiveModelSerializers::GrapeTest#test_render_helper_passes_through_options_correctly:
NoMethodError: undefined method `[]' for nil:NilClass

bin/rails test /home/runner/work/active_model_serializers/active_model_serializers/test/grape_test.rb:126

W, [2020-12-29T02:27:48.991413 #2790]  WARN -- : You are setting a key that conflicts with a built-in method Hashie::Mash#size defined in Hash. This can cause unexpected behavior when accessing the key as a property. You can still access the key via the #[] method.
W, [2020-12-29T02:27:48.991505 #2790]  WARN -- : You are setting a key that conflicts with a built-in method Hashie::Mash#size defined in Hash. This can cause unexpected behavior when accessing the key as a property. You can still access the key via the #[] method.
W, [2020-12-29T02:27:48.991581 #2790]  WARN -- : You are setting a key that conflicts with a built-in method Hashie::Mash#size defined in Hash. This can cause unexpected behavior when accessing the key as a property. You can still access the key via the #[] method.
W, [2020-12-29T02:27:48.991625 #2790]  WARN -- : You are setting a key that conflicts with a built-in method Hashie::Mash#size defined in Hash. This can cause unexpected behavior when accessing the key as a property. You can still access the key via the #[] method.
E

Error:
ActiveModelSerializers::GrapeTest#test_implicit_formatter_handles_collections:
NoMethodError: undefined method `[]' for nil:NilClass

bin/rails test /home/runner/work/active_model_serializers/active_model_serializers/test/grape_test.rb:185

...............................................................................................................................................

Finished in 2.052241s, 280.6688 runs/s, 473.6285 assertions/s.
576 runs, 972 assertions, 0 failures, 7 errors, 0 skips
rake aborted!
Command failed with status (1): [ruby -w -I"lib:lib:test" -r./test/test_helper.rb  -w -I"/home/runner/work/active_model_serializers/active_model_serializers/vendor/bundle/ruby/2.6.0/gems/rake-12.3.3/lib" "/home/runner/work/active_model_serializers/active_model_serializers/vendor/bundle/ruby/2.6.0/gems/rake-12.3.3/lib/rake/rake_test_loader.rb" "test/action_controller/adapter_selector_test.rb" "test/action_controller/explicit_serializer_test.rb" "test/action_controller/json/include_test.rb" "test/action_controller/json_api/deserialization_test.rb" "test/action_controller/json_api/errors_test.rb" "test/action_controller/json_api/fields_test.rb" "test/action_controller/json_api/linked_test.rb" "test/action_controller/json_api/pagination_test.rb" "test/action_controller/json_api/transform_test.rb" "test/action_controller/lookup_proc_test.rb" "test/action_controller/namespace_lookup_test.rb" "test/action_controller/serialization_scope_name_test.rb" "test/action_controller/serialization_test.rb" "test/active_model_serializers/adapter_for_test.rb" "test/active_model_serializers/json_pointer_test.rb" "test/active_model_serializers/logging_test.rb" "test/active_model_serializers/model_test.rb" "test/active_model_serializers/test/schema_test.rb" "test/active_model_serializers/test/serializer_test.rb" "test/active_record_test.rb" "test/adapter/attributes_test.rb" "test/adapter/deprecation_test.rb" "test/adapter/json/belongs_to_test.rb" "test/adapter/json/collection_test.rb" "test/adapter/json/fields_test.rb" "test/adapter/json/has_many_test.rb" "test/adapter/json/transform_test.rb" "test/adapter/json_api/belongs_to_test.rb" "test/adapter/json_api/collection_test.rb" "test/adapter/json_api/errors_test.rb" "test/adapter/json_api/fields_test.rb" "test/adapter/json_api/has_many_explicit_serializer_test.rb" "test/adapter/json_api/has_many_test.rb" "test/adapter/json_api/has_one_test.rb" "test/adapter/json_api/include_data_if_sideloaded_test.rb" "test/adapter/json_api/json_api_test.rb" "test/adapter/json_api/linked_test.rb" "test/adapter/json_api/links_test.rb" "test/adapter/json_api/pagination_links_test.rb" "test/adapter/json_api/parse_test.rb" "test/adapter/json_api/relationship_test.rb" "test/adapter/json_api/resource_meta_test.rb" "test/adapter/json_api/toplevel_jsonapi_test.rb" "test/adapter/json_api/transform_test.rb" "test/adapter/json_api/type_test.rb" "test/adapter/json_test.rb" "test/adapter/null_test.rb" "test/adapter/polymorphic_test.rb" "test/adapter_test.rb" "test/array_serializer_test.rb" "test/cache_test.rb" "test/collection_serializer_test.rb" "test/generators/scaffold_controller_generator_test.rb" "test/generators/serializer_generator_test.rb" "test/grape_test.rb" "test/lint_test.rb" "test/logger_test.rb" "test/poro_test.rb" "test/serializable_resource_test.rb" "test/serializers/association_macros_test.rb" "test/serializers/associations_test.rb" "test/serializers/attribute_test.rb" "test/serializers/attributes_test.rb" "test/serializers/configuration_test.rb" "test/serializers/fieldset_test.rb" "test/serializers/meta_test.rb" "test/serializers/options_test.rb" "test/serializers/read_attribute_for_serialization_test.rb" "test/serializers/reflection_test.rb" "test/serializers/root_test.rb" "test/serializers/serialization_test.rb" "test/serializers/serializer_for_test.rb" "test/serializers/serializer_for_with_namespace_test.rb" ]
/home/runner/work/active_model_serializers/active_model_serializers/vendor/bundle/ruby/2.6.0/gems/rake-12.3.3/exe/rake:27:in `<top (required)>'
/opt/hostedtoolcache/Ruby/2.6.6/x64/bin/bundle:23:in `load'
/opt/hostedtoolcache/Ruby/2.6.6/x64/bin/bundle:23:in `<main>'
Tasks: TOP => default => test
(See full trace by running task with --trace)
Error: Process completed with exit code 1.
```

Author: bf4

.github/workflows/ci.yml

@@ -0,0 +1,69 @@
+---
+
+name: CI
+
+on:
+  - "push"
+
+jobs:
+  test:
+    name: "Testing"
+    runs-on: ubuntu-18.04
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          # Recent Rubies and Rails
+          - ruby-version: '2.6'
+            rails-version: '6.1'
+          - ruby-version: '2.6'
+            rails-version: '6.0'
+          - ruby-version: '2.7'
+            rails-version: '6.0'
+          - ruby-version: '2.6'
+            rails-version: '5.2'
+          # Old Rubies and Rails
+          - ruby-version: '2.5'
+            rails-version: '5.1'
+            bundler: '1'
+          - ruby-version: '2.4'
+            rails-version: '5.0'
+            bundler: '1'
+          - ruby-version: '2.4'
+            rails-version: '4.2'
+            bundler: '1'
+          # Failing with a stack trace in active support
+          # - ruby-version: '2.4'
+          #   rails-version: '4.1'
+          #   bundler: '1'
+
+    continue-on-error: "${{ endsWith(matrix.ruby-version, 'head') }}"
+
+    env:
+      CI: "1"
+
+    steps:
+      - name:                     "Checkout Code"
+        uses:                     "actions/checkout@v2"
+        timeout-minutes:          5
+        with:
+          fetch-depth:            0
+
+      - name: Install required libs
+        run: |
+          sudo apt-get -yqq install libsqlite3-dev
+
+      - name: "Build Ruby"
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version:   "${{ matrix.ruby-version }}"
+          bundler:        "${{ matrix.bundler || 2 }}"
+          bundler-cache:  true
+        env:
+          RAILS_VERSION: ${{ matrix.rails-version }}
+
+      - name: "Run tests"
+        run: |
+          bundle exec rake
+        env:
+          RAILS_VERSION: ${{ matrix.rails-version }}

.simplecov

@@ -13,7 +13,6 @@
     <td>
       <a href="https://codeclimate.com/github/rails-api/active_model_serializers"><img src="https://codeclimate.com/github/rails-api/active_model_serializers/badges/gpa.svg" alt="Code Quality"></a>
       <a href="https://codebeat.co/projects/github-com-rails-api-active_model_serializers"><img src="https://codebeat.co/badges/a9ab35fa-8b5a-4680-9d4e-a81f9a55ebcd" alt="codebeat" ></a>
-      <a href="https://codeclimate.com/github/rails-api/active_model_serializers/coverage"><img src="https://codeclimate.com/github/rails-api/active_model_serializers/badges/coverage.svg" alt="Test Coverage"></a>
     </td>
   </tr>
   <tr>

README.md

@@ -5,10 +5,6 @@ begin
 rescue LoadError
   puts 'You must `gem install bundler` and `bundle install` to run rake tasks'
 end
-begin
-  require 'simplecov'
-rescue LoadError # rubocop:disable Lint/HandleExceptions
-end
 import('lib/tasks/rubocop.rake')
 
 Bundler::GemHelper.install_tasks
@@ -56,13 +52,20 @@ namespace :test do
     # https://github.com/rails/rails/blob/3d590add45/railties/lib/rails/generators/app_base.rb#L345-L363
     _bundle_command = Gem.bin_path('bundler', 'bundle')
     require 'bundler'
-    Bundler.with_clean_env do
+    with_clean_env = proc do
       isolated_test_files.all? do |test_file|
         command = "-w -I#{dir}/lib -I#{dir}/test #{Shellwords.shellescape(test_file)}"
         full_command = %("#{Gem.ruby}" #{command})
         system(full_command)
       end or fail 'Failures' # rubocop:disable Style/AndOr
     end
+    bundler_method =
+      if Bundler.method_defined?(:with_unbundled_env)
+        :with_unbundled_env
+      else
+        :with_clean_env
+      end
+    Bundler.public_send(bundler_method, &with_clean_env)
   end
 end
 

Rakefile

@@ -55,9 +55,8 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'will_paginate', '~> 3.0', '>= 3.0.7'
 
   spec.add_development_dependency 'bundler'
-  spec.add_development_dependency 'simplecov', '>= 0.11'
   spec.add_development_dependency 'timecop', '~> 0.7'
-  spec.add_development_dependency 'grape', ['>= 0.13', '< 0.19.1']
+  spec.add_development_dependency 'grape', '>= 0.13'
   spec.add_development_dependency 'json_schema'
-  spec.add_development_dependency 'rake', ['>= 10.0', '< 13.0']
+  spec.add_development_dependency 'rake', '>= 10.0'
 end

active_model_serializers.gemspec

@@ -18,8 +18,6 @@
 
 - [Improve code quality](https://codeclimate.com/github/rails-api/active_model_serializers/code?sort=smell_count&sort_direction=desc).
 
-- [Improve amount of code exercised by tests](https://codeclimate.com/github/rails-api/active_model_serializers/coverage?sort=covered_percent&sort_direction=asc).
-
 - [Fix RuboCop (Style) TODOS](https://github.com/rails-api/active_model_serializers/blob/master/.rubocop_todo.yml).
   - Delete and offsense, run `rake rubocop` (or possibly `rake rubocop:auto_correct`),
     and [submit a PR](CONTRIBUTING.md#submitting-a-pull-request-pr).

docs/STYLE.md

@@ -71,13 +71,13 @@ def render_using_explicit_each_serializer
       def test_render_using_explicit_serializer
         get :render_using_explicit_serializer
 
-        assert_equal 'application/json', @response.content_type
+        assert_match(%r{\Aapplication/json}, @response.content_type)
         assert_equal '{"name":"Name 1"}', @response.body
       end
 
       def test_render_array_using_explicit_serializer
         get :render_array_using_explicit_serializer
-        assert_equal 'application/json', @response.content_type
+        assert_match(%r{\Aapplication/json}, @response.content_type)
 
         expected = [
           { 'name' => 'Name 1' },
@@ -89,7 +89,7 @@ def test_render_array_using_explicit_serializer
 
       def test_render_array_using_implicit_serializer
         get :render_array_using_implicit_serializer
-        assert_equal 'application/json', @response.content_type
+        assert_match(%r{\Aapplication/json}, @response.content_type)
 
         expected = [
           { 'name' => 'Name 1' },