CSVダウンロード機能を実装

app/service/download_csv_service.rb

@@ -0,0 +1,23 @@
+require 'csv'
+
+class DownloadCsvService
+  # スプレッドシートからのダウンロードを大前提とする
+  def initialize(spreadsheet_id:, worksheet_name:)
+    @fetcher = FetchDataTableService::FromSpreadsheet.new(
+      spreadsheet_id:,
+      worksheet_name:
+    )
+  end
+
+  def execute(filepath)
+    csv_contents = CSV.generate do |csv|
+      csv << @fetcher.headers
+      @fetcher.rows.each do |row|
+        csv << row
+      end
+    end
+
+    file_service = FileService.new(filepath)
+    file_service.write(csv_contents)
+  end
+end

app/service/fetch_data_table_service/from_spreadsheet.rb

@@ -1,6 +1,6 @@
 module FetchDataTableService
   class FromSpreadsheet < Base
-    def initialize(spreadsheet_id, worksheet_name)
+    def initialize(spreadsheet_id:, worksheet_name:)
       super
 
       sheets_api = SpreadsheetService::SheetsApi.create

app/service/file_service.rb

@@ -1,5 +1,11 @@
 class FileService
-  def initialize
-    # TODO: 書く
+  def initialize(filepath)
+    @filepath = filepath
+  end
+
+  def write(text)
+    File.open(@filepath, 'w') do |file|
+      file.puts text
+    end
   end
 end

app/service/import_service/base.rb

@@ -36,9 +36,9 @@ def data_table_from_csv(csv_filepath:)
     end
 
     def data_table_from_spreadsheet(spreadsheet_title:, worksheet_name:)
-      spreadsheet_id = SpreadsheetService::SheetId.retrieve(spreadsheet_title)
+      spreadsheet_id = SpreadsheetService::SheetId.title_to_id(spreadsheet_title)
 
-      FetchDataTableService::FromSpreadsheet.new(spreadsheet_id, worksheet_name)
+      FetchDataTableService::FromSpreadsheet.new(spreadsheet_id:, worksheet_name:)
     end
   end
 end

app/service/spreadsheet_service/sheet_id.rb

@@ -1,16 +1,12 @@
 module SpreadsheetService
   class SheetId
     class << self
-      def retrieve(spreadsheet_title)
-        title_to_id[spreadsheet_title]
-      end
-
       # 新規追加時はシートへの権限の付与も忘れないこと
-      def title_to_id
+      def title_to_id(title)
         {
           'basic_attributes' => ENV.fetch('SPREADSHEET_ID_BASIC_ATTRIBUTES'),
           'products' => ENV.fetch('SPREADSHEET_ID_PRODUCTS')
-        }
+        }.fetch(title)
       end
     end
   end

spec/service/download_csv_service_spec.rb

@@ -0,0 +1,34 @@
+require 'rails_helper'
+
+describe DownloadCsvService do
+  let(:service) do
+    DownloadCsvService.new(
+      spreadsheet_id: SpreadsheetService::SheetId.title_to_id('basic_attributes'),
+      worksheet_name: 'stars'
+    )
+  end
+
+  describe 'CSVファイル' do
+    it '期待どおりにダウンロード（＝生成）されていること' do
+      service.execute('tmp/vault_test.csv')
+
+      expect(File.exist?('tmp/vault_test.csv')).to be_truthy
+    end
+
+    it '一行目（ヘッダ）の内容が期待どおりであること' do
+      service.execute('tmp/vault_test_check_first_row.csv')
+
+      expect(
+        File.open('tmp/vault_test_check_first_row.csv').readline.chomp
+      ).to eq 'id,seating_order,name,name_en'
+    end
+
+    it '二行目（内容の行の一行目）の内容が期待どおりであること' do
+      service.execute('tmp/vault_test_check_second_row.csv')
+
+      expect(
+        File.open('tmp/vault_test_check_first_row.csv').readlines[1].chomp
+      ).to eq '1,1,天魁星,Leader Star'
+    end
+  end
+end

spec/service/import_service/star_spec.rb

@@ -1,13 +1,6 @@
 require 'rails_helper'
 
 describe ImportService::Star do
-  let(:service) do
-    ImportService::Star.new(
-      spreadsheet_title: 'basic_attributes',
-      worksheet_name: 'stars'
-    )
-  end
-
   it 'ソースをもとにしたサービスのオブジェクトが生成されること' do
     expect(
       ImportService::Star.new(