Use data_source_exists? in generators and add column backend spec

lib/generators/rails/mobility/backend_generators/base.rb

@@ -31,8 +31,14 @@ def attributes_with_index
 
       private
 
-      def table_exists?
-        connection.table_exists?(table_name)
+      def check_data_source!
+        unless data_source_exists?
+          raise NoTableDefined, "The table #{table_name} does not exist. Create it first before generating translated columns."
+        end
+      end
+
+      def data_source_exists?
+        connection.data_source_exists?(table_name)
       end
 
       delegate :connection, to: ::ActiveRecord::Base
@@ -57,5 +63,7 @@ def migration_file
         "create_#{file_name}_#{attributes.map(&:name).join('_and_')}_translations_for_mobility_#{backend}_backend".freeze
       end
     end
+
+    class NoTableDefined < StandardError; end
   end
 end

lib/generators/rails/mobility/backend_generators/column_backend.rb

@@ -8,16 +8,8 @@ class ColumnBackend < Mobility::BackendGenerators::Base
 
       def initialize(*args)
         super
-        unless table_exists?
-          raise NoTableDefined, "The table #{table_name} does not exist. Create it first before generating translated columns."
-        end
-        unless I18n.available_locales.present?
-          raise NoAvailableLocales, "You must set I18n.available_locales to use the column backend generator."
-        end
+        check_data_source!
       end
     end
-
-    class NoTableDefined < StandardError; end
-    class NoAvailableLocales < StandardError; end
   end
 end

lib/generators/rails/mobility/backend_generators/table_backend.rb

@@ -7,7 +7,7 @@ class TableBackend < Mobility::BackendGenerators::Base
       source_root File.expand_path("../../templates", __FILE__)
 
       def create_migration_file
-        if table_exists? && !self.class.migration_exists?(migration_dir, migration_file)
+        if data_source_exists? && !self.class.migration_exists?(migration_dir, migration_file)
           migration_template "#{backend}_migration.rb", "db/migrate/#{migration_file}.rb"
         else
           super

spec/generators/rails/mobility/translations_generator_spec.rb

@@ -0,0 +1,103 @@
+require "spec_helper"
+
+describe Mobility::TranslationsGenerator, type: :generator, orm: :active_record do
+  require "generator_spec/test_case"
+  include GeneratorSpec::TestCase
+  require "generators/rails/mobility/translations_generator"
+
+  destination File.expand_path("../tmp", __FILE__)
+
+  after(:all) { prepare_destination }
+
+  describe "--backend=table" do
+    before(:all) do
+      prepare_destination
+      run_generator %w(Post title:string:index content:text --backend=table)
+    end
+
+    context "translations table does not yet exist" do
+      it "generates table translations migration creating translations table" do
+        expect(destination_root).to have_structure do
+          directory "db" do
+            directory "migrate" do
+              migration "create_post_title_and_content_translations_for_mobility_table_backend" do
+                contains "class CreatePostTitleAndContentTranslationsForMobilityTableBackend < ActiveRecord::Migration[5.0]"
+                contains "def change"
+                contains "create_table :post_translations"
+                contains "t.string :title"
+                contains "t.text :content"
+                contains "t.string  :locale, null: false"
+                contains "t.integer :post_id, null: false"
+                contains "t.timestamps null: false"
+                contains "add_index :post_translations, :post_id, name: :index_post_translations_on_post_id"
+                contains "add_index :post_translations, :locale, name: :index_post_translations_on_locale"
+                contains "add_index :post_translations, [:post_id, :locale], name: :index_post_translations_on_post_id_and_locale, unique: true"
+                contains "add_index :post_translations, :title"
+              end
+            end
+          end
+        end
+      end
+    end
+
+    context "translation table already exists" do
+      before { ActiveRecord::Base.connection.create_table :post_translations }
+
+      it "generates table translations migration adding columns to existing translations table" do
+        expect(destination_root).to have_structure do
+          directory "db" do
+            directory "migrate" do
+              migration "create_post_title_and_content_translations_for_mobility_table_backend" do
+                contains "class CreatePostTitleAndContentTranslationsForMobilityTableBackend < ActiveRecord::Migration[5.0]"
+                contains "add_column :post_translations, :title, :string"
+                contains "add_index :post_translations, :title"
+                contains "add_column :post_translations, :content, :text"
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+
+  describe "--backend=column" do
+    before { prepare_destination }
+
+    context "model table does not exist" do
+      it "raises NoTableDefined error" do
+        expect { run_generator %w(Foo title:string:index content:text --backend=column) }.to raise_error(Mobility::BackendGenerators::NoTableDefined)
+      end
+    end
+
+    context "model table exists" do
+      before do
+        ActiveRecord::Base.connection.create_table :foos
+        available_locales = I18n.available_locales
+        I18n.available_locales = [:en, :ja, :de]
+        run_generator %w(Foo title:string:index content:text --backend=column)
+        I18n.available_locales = available_locales
+      end
+
+      it "generates column translations migration adding columns for each locale to model table" do
+        expect(destination_root).to have_structure do
+          directory "db" do
+            directory "migrate" do
+              migration "create_foo_title_and_content_translations_for_mobility_column_backend" do
+                contains "class CreateFooTitleAndContentTranslationsForMobilityColumnBackend < ActiveRecord::Migration[5.0]"
+                contains "add_column :foos, :title_en, :string"
+                contains "add_index :foos, :title_en"
+                contains "add_column :foos, :title_ja, :string"
+                contains "add_index :foos, :title_ja"
+                contains "add_column :foos, :title_de, :string"
+                contains "add_index :foos, :title_de"
+                contains "add_column :foos, :content_en, :text"
+                contains "add_column :foos, :content_ja, :text"
+                contains "add_column :foos, :content_de, :text"
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end if Mobility::Loaded::Rails