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Testing PaperTrail Installation Generator Implementation in paper_trail

This test suite validates the PaperTrail installation generator functionality, ensuring proper database migration creation and configuration options. It covers various generator scenarios including default installation, versioning with changes tracking, and UUID support.

Test Coverage Overview

The test suite provides comprehensive coverage of the PaperTrail install generator’s capabilities.

Key areas tested include:

Default migration generation for versions table
Optional object changes column addition
UUID support for item tracking
Database adapter-specific configurations

Implementation Analysis

The testing approach uses RSpec’s generator testing utilities with GeneratorSpec::TestCase integration. It implements isolated test environments through temporary directory manipulation and uses structured expectations to verify generated migration files and their contents.

Technical patterns include:

Dynamic version-specific migration class generation
Database adapter-aware table options
Conditional schema configurations

Technical Details

Testing tools and configuration:

RSpec framework with generator_spec extension
Temporary directory management for isolation
Migration file structure validation
Dynamic ActiveRecord version detection
MySQL adapter-specific handling

Best Practices Demonstrated

The test suite exemplifies high-quality testing practices through thorough isolation and comprehensive verification.

Notable practices include:

Clean test environment management
Granular feature testing
Dynamic adaptation to different database configurations
Explicit test case organization
Clear separation of concerns between test scenarios

paper-trail-gem/paper_trail

spec/generators/paper_trail/install_generator_spec.rb

            
# frozen_string_literal: true

require "spec_helper"
require "generator_spec/test_case"
require "generators/paper_trail/install/install_generator"

RSpec.describe PaperTrail::InstallGenerator, type: :generator do
  include GeneratorSpec::TestCase
  destination File.expand_path("tmp", __dir__)

  after do
    prepare_destination # cleanup the tmp directory
  end

  describe "no options" do
    before do
      prepare_destination
      run_generator
    end

    it "generates a migration for creating the 'versions' table" do
      expected_parent_class = lambda {
        old_school = "ActiveRecord::Migration"
        ar_version = ActiveRecord::VERSION
        format("%s[%d.%d]", old_school, ar_version::MAJOR, ar_version::MINOR)
      }.call
      expected_create_table_options = lambda {
        if described_class::MYSQL_ADAPTERS.include?(ActiveRecord::Base.connection.class.name)
          ', options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci"'
        else
          ""
        end
      }.call
      expected_item_type_options = lambda {
        if described_class::MYSQL_ADAPTERS.include?(ActiveRecord::Base.connection.class.name)
          ", null: false, limit: 191"
        else
          ", null: false"
        end
      }.call
      expect(destination_root).to(
        have_structure {
          directory("db") {
            directory("migrate") {
              migration("create_versions") {
                contains("class CreateVersions < " + expected_parent_class)
                contains "def change"
                contains "create_table :versions#{expected_create_table_options}"
                contains "  t.string   :item_type#{expected_item_type_options}"
              }
            }
          }
        }
      )
      expect(destination_root).not_to(
        have_structure {
          directory("db") {
            directory("migrate") {
              migration("add_object_changes_to_versions")
            }
          }
        }
      )
    end
  end

  describe "`--with-changes` option set to `true`" do
    before do
      prepare_destination
      run_generator %w[--with-changes]
    end

    it "generates a migration for creating the 'versions' table" do
      expect(destination_root).to(
        have_structure {
          directory("db") {
            directory("migrate") {
              migration("create_versions") {
                contains "class CreateVersions"
                contains "def change"
                contains "create_table :versions"
              }
            }
          }
        }
      )
    end

    it "generates a migration for adding the 'object_changes' column to the 'versions' table" do
      expect(destination_root).to(
        have_structure {
          directory("db") {
            directory("migrate") {
              migration("add_object_changes_to_versions") {
                contains "class AddObjectChangesToVersions"
                contains "def change"
                contains "add_column :versions, :object_changes, :text"
              }
            }
          }
        }
      )
    end
  end

  describe "`--uuid` option set to `true`" do
    before do
      prepare_destination
      run_generator %w[--uuid]
    end

    it "generates a migration for creating the 'versions' table with item_id type string" do
      expected_item_id_type = "string"
      expect(destination_root).to(
        have_structure {
          directory("db") {
            directory("migrate") {
              migration("create_versions") {
                contains "t.#{expected_item_id_type}   :item_id,   null: false"
              }
            }
          }
        }
      )
    end

    it "generates a migration for creating the 'versions' table with primary key as uuid type" do
      expected_primary_key_type = "uuid"
      expect(destination_root).to(
        have_structure {
          directory("db") {
            directory("migrate") {
              migration("create_versions") {
                contains ", id: :#{expected_primary_key_type}"
              }
            }
          }
        }
      )
    end
  end
end