Warn and prompt when generating duplicate migrations

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    s3_multipart (0.0.10.5)
+    s3_multipart (0.0.10.6)
       uuid (>= 2.3.6)
       xml-simple (>= 1.1.2)
 
@@ -70,6 +70,9 @@ GEM
       multi_json (~> 1.0)
     ffi (1.2.0)
     fssm (0.2.9)
+    generator_spec (0.9.3)
+      activesupport (>= 3.0.0)
+      railties (>= 3.0.0)
     hike (1.2.1)
     i18n (0.6.1)
     journey (1.0.4)
@@ -147,17 +150,17 @@ GEM
       rack (~> 1.0)
       tilt (~> 1.1, != 1.3.0)
     sqlite3 (1.3.6)
-    systemu (2.6.4)
+    systemu (2.6.5)
     thor (0.16.0)
     tilt (1.3.3)
     treetop (1.4.12)
       polyglot
       polyglot (>= 0.3.1)
     tzinfo (0.3.35)
-    uuid (2.3.7)
+    uuid (2.3.8)
       macaddr (~> 1.0)
     websocket (1.0.6)
-    xml-simple (1.1.3)
+    xml-simple (1.1.5)
     xpath (1.0.0)
       nokogiri (~> 1.3)
 
@@ -171,6 +174,7 @@ DEPENDENCIES
   coffee-rails (~> 3.2.1)
   combustion (~> 0.3.3)
   compass-rails
+  generator_spec
   jquery-ui-rails
   rails
   rspec-rails (~> 2.14, >= 2.14.2)

lib/generators/s3_multipart/install_generator.rb

@@ -1,13 +1,18 @@
+require_relative 'migration_existence_validation_helper.rb'
 require 'rails/generators'
 
 module S3Multipart
   class InstallGenerator < Rails::Generators::Base
+    include MigrationExistenceValidationHelper
+
     desc "Generates all the necessary setup for integration with the S3 Multipart gem"
 
     source_root File.expand_path("../templates", __FILE__)
 
     def create_migrations
-      copy_file "uploads_table_migration.rb", "db/migrate/#{migration_time}_create_s3_multipart_uploads.rb"
+      prompt_if_exists for_file: migration_name, to_execute: ->{
+        copy_file "uploads_table_migration.rb", "db/migrate/#{migration_time}_#{migration_name}.rb"
+      }
     end
 
     def create_configuration_files
@@ -18,13 +23,16 @@ def create_configuration_files
 
     private
 
+      def migration_name
+        'create_s3_multipart_uploads'
+      end
+
       def migration_time
         Time.now.strftime("%Y%m%d%H%M%S")
       end
 
       def model_constant
         model.split("_").map(&:capitalize).join()
       end
-
   end
 end

lib/generators/s3_multipart/install_new_migrations_generator.rb

@@ -1,14 +1,22 @@
+require_relative 'migration_existence_validation_helper.rb'
 require 'rails/generators'
 
 module S3Multipart
   class InstallNewMigrationsGenerator < Rails::Generators::Base
+    include MigrationExistenceValidationHelper
+
     desc "Generates the migrations necessary when updating the gem to the latest version"
 
     source_root File.expand_path("../templates", __FILE__)
 
     def create_latest_migrations
-      copy_file "add_size_column_to_s3_multipart_uploads.rb", "db/migrate/#{migration_time}_add_size_to_s3_multipart_uploads.rb"
-      copy_file "add_context_column_to_s3_multipart_uploads.rb", "db/migrate/#{migration_time}_add_context_to_s3_multipart_uploads.rb"
+      prompt_if_exists for_file: size_column_migration_name, to_execute: ->{
+        copy_file "#{size_column_migration_name}.rb", "db/migrate/#{migration_time}_#{size_column_migration_name}.rb"
+      }
+
+      prompt_if_exists for_file: context_column_migration_name, to_execute: ->{
+        copy_file "#{context_column_migration_name}.rb", "db/migrate/#{migration_time}_#{context_column_migration_name}.rb"
+      }
     end
 
     private
@@ -17,5 +25,12 @@ def migration_time
         Time.now.strftime("%Y%m%d%H%M%S")
       end
 
+      def size_column_migration_name
+        'add_size_to_s3_multipart_uploads'
+      end
+
+      def context_column_migration_name
+        'add_context_to_s3_multipart_uploads'
+      end
   end
 end

lib/generators/s3_multipart/migration_existence_validation_helper.rb

@@ -0,0 +1,29 @@
+module MigrationExistenceValidationHelper
+  attr_reader :migration_name
+
+  def prompt_if_exists(for_file:, to_execute:)
+    @migration_name = for_file
+
+    if matching_migrations.length > 0
+      say_status('conflict', matching_migrations.join(', '), :red)
+      to_execute.call if agree_to_create_file
+    else
+      to_execute.call
+    end
+  end
+
+  private
+
+  def agree_to_create_file
+    yes? "#{matching_migrations.length > 1 ? 'Migrations exist' : 'Migration exists'}, "\
+      "creating a new migration may cause a migration error. Do you want to create the file? (y/n)"
+  end
+
+  def migration_file_path
+    "db/migrate/*_#{migration_name}.rb"
+  end
+
+  def matching_migrations
+    Dir[migration_file_path]
+  end
+end

lib/generators/s3_multipart/uploader_generator.rb

@@ -1,7 +1,10 @@
+require_relative 'migration_existence_validation_helper.rb'
 require 'rails/generators'
 
 module S3Multipart
   class UploaderGenerator < Rails::Generators::Base
+    include MigrationExistenceValidationHelper
+
     desc "Generates an uploader for use with the S3 Multipart gem"
 
     source_root File.expand_path("../templates", __FILE__)
@@ -16,11 +19,17 @@ def create_uploader
 
     def create_migrations
       # return unless options.migrations?
-      template "add_uploader_column_to_model.rb", "db/migrate/#{migration_time}_add_uploader_to_#{model}.rb"
+      prompt_if_exists for_file: migration_name, to_execute: ->{
+        template "add_uploader_column_to_model.rb", "db/migrate/#{migration_time}_#{migration_name}.rb"
+      }
     end
 
     private
 
+      def migration_name
+        "add_uploader_to_#{model}"
+      end
+
       def migration_time
         Time.now.strftime("%Y%m%d%H%M%S")
       end
@@ -30,4 +39,4 @@ def model_constant
       end
 
   end
-end
+end

s3_multipart.gemspec

@@ -25,5 +25,6 @@ Gem::Specification.new do |s|
   s.add_development_dependency "rails"
   s.add_development_dependency "sqlite3"
   s.add_development_dependency 'rspec-rails', '~> 2.14', '>= 2.14.2'
+  s.add_development_dependency 'generator_spec'
   s.add_development_dependency 'capybara'
 end

spec/generators/install_generator_spec.rb

@@ -0,0 +1,25 @@
+require 'spec_helper.rb'
+require_relative '../../lib/generators/s3_multipart/install_generator.rb'
+
+describe S3Multipart::InstallGenerator, type: :generator do
+  destination File.expand_path('../../../tmp', __FILE__)
+
+  before(:all) do
+    prepare_destination
+    mkdir "#{destination_root}/config"
+    touch "#{destination_root}/config/routes.rb"
+    run_generator
+  end
+
+  it 'creates a migration for an S3 uploads table' do
+    assert_migration "#{destination_root}/db/migrate/create_s3_multipart_uploads.rb"
+  end
+
+  it 'creates an AWS credential YAML configuration file' do
+    assert_file 'config/aws.yml'
+  end
+
+  it 'mounts the gem engine in the app routes' do
+    expect(run_generator).to match 'mount S3Multipart::Engine => "/s3_multipart"'
+  end
+end

spec/generators/install_new_migrations_generator_spec.rb

@@ -0,0 +1,21 @@
+require 'spec_helper.rb'
+require_relative '../../lib/generators/s3_multipart/install_new_migrations_generator.rb'
+
+describe S3Multipart::InstallNewMigrationsGenerator, type: :generator do
+  destination File.expand_path('../../../tmp', __FILE__)
+
+  before(:all) do
+    prepare_destination
+    run_generator
+  end
+
+  it 'creates a migration to add a size column to the S3 uploads table' do
+    migration_exists = !!Dir["#{destination_root}/db/migrate/*_add_size_to_s3_multipart_uploads.rb"].length
+    expect(migration_exists).to be_true
+  end
+
+  it 'creates a migration to add a context column to the S3 uploads table' do
+    migration_exists = !!Dir["#{destination_root}/db/migrate/*_add_context_to_s3_multipart_uploads.rb"].length
+    expect(migration_exists).to be_true
+  end
+end

spec/generators/uploader_generator_spec.rb

@@ -0,0 +1,29 @@
+require 'spec_helper.rb'
+require_relative '../../lib/generators/s3_multipart/uploader_generator.rb'
+
+describe S3Multipart::UploaderGenerator, type: :generator do
+  destination File.expand_path('../../../tmp', __FILE__)
+  arguments %w(foo)
+
+  before(:all) do
+    prepare_destination
+    mkdir "#{destination_root}/app"
+    run_generator
+  end
+
+  it 'creates a migration to add an uploader column to the specified model table' do
+    assert_migration "#{destination_root}/db/migrate/add_uploader_to_foo.rb"
+  end
+
+  it 'creates an uploaders folder' do
+    assert_directory "#{destination_root}/app/uploaders"
+  end
+
+  it 'creates a multipart folder in the uploaders folder' do
+    assert_directory "#{destination_root}/app/uploaders/multipart"
+  end
+
+  it 'adds an uploader for the specified model in the uploaders multipart folder' do
+    assert_file "#{destination_root}/app/uploaders/multipart/foo_uploader.rb"
+  end
+end

spec/spec_helper.rb

@@ -10,6 +10,8 @@
 require 'rspec/rails'
 require 'capybara/rails'
 
+require 'generator_spec'
+
 RSpec.configure do |config|
   #config.use_transactional_fixtures = true
 end