Save Gemfiles Use Case

.gitignore

@@ -1 +1,3 @@
 public/cache/*.html
+tmp/*
+!tmp/.keep

lib/loader.rb

@@ -13,6 +13,7 @@
 require_relative './use_cases/slack/schedulers/every_day'
 require_relative './use_cases/slack/schedulers/weekday'
 require_relative './use_cases/fetch_gemfiles'
+require_relative './use_cases/save_gemfiles'
 require_relative './gateways/pull_request'
 require_relative './gateways/pull_request_count'
 require_relative './gateways/slack_message'

lib/use_cases/save_gemfiles.rb

@@ -0,0 +1,24 @@
+module UseCases
+  class SaveGemfiles
+    def initialize(fetch_gemfiles:, file: File)
+      @fetch_gemfiles = fetch_gemfiles
+      @file = file
+    end
+
+    def execute
+      results = fetch_gemfiles.execute
+      results.each do |result|
+        save_gemfile(result.fetch(:application_name), result.fetch(:gemfile_contents))
+      end
+    end
+
+    private
+
+    attr_reader :fetch_gemfiles, :file
+
+    def save_gemfile(application_name, file_contents)
+      gemfile_path = "tmp/#{application_name}_gemfile.lock"
+      file.open(gemfile_path, 'w') { |f| f.write(file_contents) }
+    end
+  end
+end

spec/use_cases/save_gemfiles_spec.rb

@@ -0,0 +1,35 @@
+describe UseCases::SaveGemfiles do
+  context 'Given FetchGemfiles' do
+    it 'calls execute' do
+      fetch_gemfiles = spy
+      described_class.new(fetch_gemfiles: fetch_gemfiles).execute
+
+      expect(fetch_gemfiles).to have_received(:execute)
+    end
+  end
+
+  context 'Given no Gemfiles' do
+    it 'does not save them' do
+      fetch_gemfiles = double(execute: [])
+      file_gateway = spy
+      described_class.new(fetch_gemfiles: fetch_gemfiles, file: file_gateway).execute
+
+      expect(file_gateway).to_not have_received(:execute)
+    end
+  end
+
+  context 'Given one Gemfile' do
+    it 'saves it' do
+      fetch_gemfiles = double(execute: [
+        {
+          application_name: 'foo-app',
+          gemfile_contents: 'some contents'
+        }
+      ])
+      file_gateway = spy
+      described_class.new(fetch_gemfiles: fetch_gemfiles, file: file_gateway).execute
+
+      expect(file_gateway).to have_received(:open).with('tmp/foo-app_gemfile.lock', 'w')
+    end
+  end
+end