Add Docker support for multi-version Rails testing

.dockerignore

@@ -0,0 +1,35 @@
+# Git
+.git
+.gitignore
+.github
+
+# Claude/AI configuration
+.claude
+.serena
+CLAUDE.md
+
+# Documentation
+*.md
+!README.md
+
+# Test artifacts
+coverage/
+test_db
+*.sqlite3
+.last_run.json
+.resultset.json
+
+# Ruby/bundler
+.bundle
+vendor/bundle
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# Editor files
+.vscode
+.idea
+*.swp
+*.swo
+*~

.gitignore

@@ -8,7 +8,7 @@
 Gemfile.lock
 InstalledFiles
 _yardoc
-coverage
+coverage/
 doc/
 lib/bundler/man
 pkg
@@ -17,10 +17,11 @@ spec/reports
 test/tmp
 test/version_tmp
 tmp
-coverage
 test/log
 log/*.log
 test_db
 test_db-journal
+test/test_db-shm
+test/test_db-wal
 .idea
 *.iml

Dockerfile

@@ -0,0 +1,22 @@
+# Dockerfile for testing jsonapi-resources with multiple Rails versions
+
+FROM ruby:3.2
+
+# Install dependencies
+RUN apt-get update -qq && \
+    apt-get install -y build-essential libpq-dev nodejs && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+# Set working directory
+WORKDIR /app
+
+# Copy Gemfile and gemspec
+COPY Gemfile jsonapi-resources.gemspec ./
+COPY lib/jsonapi/resources/version.rb ./lib/jsonapi/resources/
+
+# Install bundler
+RUN gem install bundler
+
+# Note: bundle install will happen at runtime with specific RAILS_VERSION
+# This allows testing multiple Rails versions without rebuilding the image

Dockerfile.ruby2.7

@@ -0,0 +1,22 @@
+# Dockerfile for testing jsonapi-resources with Rails 5.1-7.0 (Ruby 2.7)
+
+FROM ruby:2.7
+
+# Install dependencies
+RUN apt-get update -qq && \
+    apt-get install -y build-essential libpq-dev nodejs && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+# Set working directory
+WORKDIR /app
+
+# Copy Gemfile and gemspec
+COPY Gemfile jsonapi-resources.gemspec ./
+COPY lib/jsonapi/resources/version.rb ./lib/jsonapi/resources/
+
+# Install bundler (Ruby 2.7 requires bundler < 2.5)
+RUN gem install bundler -v 2.4.22
+
+# Note: bundle install will happen at runtime with specific RAILS_VERSION
+# This allows testing multiple Rails versions without rebuilding the image

Dockerfile.ruby3.1

@@ -0,0 +1,24 @@
+# Dockerfile for testing jsonapi-resources with Rails 6.1-8.1 (Ruby 3.1.5)
+
+FROM ruby:3.1.5
+
+# Install dependencies
+RUN apt-get update -qq && \
+    apt-get install -y build-essential libpq-dev nodejs && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+# Set working directory
+WORKDIR /app
+
+# Copy Gemfile and gemspec
+COPY Gemfile jsonapi-resources.gemspec ./
+COPY lib/jsonapi/resources/version.rb ./lib/jsonapi/resources/
+
+# Install specific bundler version for compatibility
+RUN gem install bundler -v 2.4.14 --no-document && \
+    gem install bundler -v 2.4.14 --install-dir /usr/local/bundle --no-document && \
+    bundle --version
+
+# Note: bundle install will happen at runtime with specific RAILS_VERSION
+# This allows testing multiple Rails versions without rebuilding the image

Dockerfile.ruby3.4

@@ -0,0 +1,24 @@
+# Dockerfile for testing jsonapi-resources with Rails 8.0-8.1 (Ruby 3.4)
+
+FROM ruby:3.4
+
+# Install dependencies
+RUN apt-get update -qq && \
+    apt-get install -y build-essential libpq-dev nodejs && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+# Set working directory
+WORKDIR /app
+
+# Copy Gemfile and gemspec
+COPY Gemfile jsonapi-resources.gemspec ./
+COPY lib/jsonapi/resources/version.rb ./lib/jsonapi/resources/
+
+# Install specific bundler version for compatibility
+RUN gem install bundler -v 2.4.14 --no-document && \
+    gem install bundler -v 2.4.14 --install-dir /usr/local/bundle --no-document && \
+    bundle --version
+
+# Note: bundle install will happen at runtime with specific RAILS_VERSION
+# This allows testing multiple Rails versions without rebuilding the image

docker-compose.yml

@@ -0,0 +1,121 @@
+services:
+  # Base service definition for Ruby 3.1.5 (Rails 6.1-8.1)
+  test-base: &test-base
+    build:
+      context: .
+      dockerfile: Dockerfile.ruby3.1
+    volumes:
+      - .:/app
+      - bundle-cache-ruby31:/usr/local/bundle
+    working_dir: /app
+    stdin_open: true
+    tty: true
+
+  # Base service definition for Ruby 2.7 (Rails 5.1-6.0)
+  test-base-ruby27: &test-base-ruby27
+    build:
+      context: .
+      dockerfile: Dockerfile.ruby2.7
+    volumes:
+      - .:/app
+      - bundle-cache-ruby27:/usr/local/bundle
+    working_dir: /app
+    stdin_open: true
+    tty: true
+
+  # Base service definition for Ruby 3.4 (Rails 8.0-8.1)
+  test-base-ruby34: &test-base-ruby34
+    build:
+      context: .
+      dockerfile: Dockerfile.ruby3.4
+    volumes:
+      - .:/app
+      - bundle-cache-ruby34:/usr/local/bundle
+    working_dir: /app
+    stdin_open: true
+    tty: true
+
+  # Rails 5.1.7
+  rails-5.1:
+    <<: *test-base-ruby27
+    container_name: jsonapi-rails-5.1
+    environment:
+      - RAILS_VERSION=5.1.7
+    command: bash -c "rm -f Gemfile.lock && bundle install && bundle exec rake test"
+
+  # Rails 5.2.8.1
+  rails-5.2:
+    <<: *test-base-ruby27
+    container_name: jsonapi-rails-5.2
+    environment:
+      - RAILS_VERSION=5.2.8.1
+    command: bash -c "rm -f Gemfile.lock && bundle install && bundle exec rake test"
+
+  # Rails 6.0.6
+  rails-6.0:
+    <<: *test-base-ruby27
+    container_name: jsonapi-rails-6.0
+    environment:
+      - RAILS_VERSION=6.0.6
+    command: bash -c "rm -f Gemfile.lock && bundle install && bundle exec rake test"
+
+  # Rails 6.1.7.10
+  rails-6.1:
+    <<: *test-base
+    container_name: jsonapi-rails-6.1
+    environment:
+      - RAILS_VERSION=6.1.7.10
+    command: bash -c "rm -f Gemfile.lock && /usr/local/bin/bundler _2.4.14_ install && /usr/local/bin/bundler _2.4.14_ exec rake test"
+
+  # Rails 7.0.10
+  rails-7.0:
+    <<: *test-base
+    container_name: jsonapi-rails-7.0
+    environment:
+      - RAILS_VERSION=7.0.10
+    command: bash -c "rm -f Gemfile.lock && /usr/local/bin/bundler _2.4.14_ install && /usr/local/bin/bundler _2.4.14_ exec rake test"
+
+  # Rails 7.1.6
+  rails-7.1:
+    <<: *test-base
+    container_name: jsonapi-rails-7.1
+    environment:
+      - RAILS_VERSION=7.1.6
+    command: bash -c "rm -f Gemfile.lock && /usr/local/bin/bundler _2.4.14_ install && /usr/local/bin/bundler _2.4.14_ exec rake test"
+
+  # Rails 7.2.3
+  rails-7.2:
+    <<: *test-base
+    container_name: jsonapi-rails-7.2
+    environment:
+      - RAILS_VERSION=7.2.3
+    command: bash -c "rm -f Gemfile.lock && /usr/local/bin/bundler _2.4.14_ install && /usr/local/bin/bundler _2.4.14_ exec rake test"
+
+  # Rails 8.0.4 (Ruby 3.4 required)
+  rails-8.0:
+    <<: *test-base-ruby34
+    container_name: jsonapi-rails-8.0
+    environment:
+      - RAILS_VERSION=8.0.4
+    command: bash -c "rm -f Gemfile.lock && /usr/local/bin/bundler _2.4.14_ install && /usr/local/bin/bundler _2.4.14_ exec rake test"
+
+  # Rails 8.1.2 (Ruby 3.4 required)
+  rails-8.1:
+    <<: *test-base-ruby34
+    container_name: jsonapi-rails-8.1
+    environment:
+      - RAILS_VERSION=8.1.2
+    command: bash -c "rm -f Gemfile.lock && /usr/local/bin/bundler _2.4.14_ install && /usr/local/bin/bundler _2.4.14_ exec rake test"
+
+  # Interactive shell for debugging (defaults to Rails 8.1)
+  shell:
+    <<: *test-base
+    container_name: jsonapi-shell
+    environment:
+      - RAILS_VERSION=${RAILS_VERSION:-8.1.2}
+    command: /bin/bash
+
+volumes:
+  bundle-cache-ruby31:
+  bundle-cache-ruby27:
+  bundle-cache-ruby34:

test/test_helper.rb

@@ -78,6 +78,25 @@ class TestApp < Rails::Application
 require 'jsonapi-resources'
 require 'pry'
 
+# Fix Psych::DisallowedClass error for Rails 6.0 with Ruby 2.7+
+# In test environment, allow all classes from YAML (safe for test fixtures)
+if defined?(Psych::VERSION) && Psych::VERSION.to_f >= 3.1 && Rails::VERSION::MAJOR == 6 && Rails::VERSION::MINOR == 0
+  require 'psych'
+
+  # Patch Psych.load to use unsafe_load in test environment
+  # This is safe because we're only loading trusted test fixtures
+  module Psych
+    class << self
+      alias_method :safe_load_original, :load
+
+      def load(yaml, *args, **kwargs)
+        # Use unsafe_load to allow Date, Time, DateTime from YAML
+        unsafe_load(yaml)
+      end
+    end
+  end
+end
+
 require File.expand_path('../helpers/value_matchers', __FILE__)
 require File.expand_path('../helpers/assertions', __FILE__)
 require File.expand_path('../helpers/functional_helpers', __FILE__)