Clean up database configs for railties

I need to add a sharded config and while making that test realized that
this would be a lot easier to read as individualized methods. This
change is a small refactoring to make the railtie tests database
configurations easier to use and read.

railties/test/isolation/abstract_unit.rb

@@ -123,9 +123,49 @@ module TestHelpers
         end
       end
 
-      if options[:multi_db]
       File.open("#{app_path}/config/database.yml", "w") do |f|
-          f.puts <<-YAML
+        if options[:multi_db]
+          f.puts multi_db_database_configs
+        else
+          f.puts default_database_configs
+        end
+      end
+
+      add_to_config <<-RUBY
+        config.hosts << proc { true }
+        config.eager_load = false
+        config.session_store :cookie_store, key: "_myapp_session"
+        config.cache_store = :mem_cache_store
+        config.active_support.deprecation = :log
+        config.action_controller.allow_forgery_protection = false
+      RUBY
+    end
+
+    def teardown_app
+      ENV["RAILS_ENV"] = @prev_rails_env if @prev_rails_env
+      FileUtils.rm_rf(tmp_path)
+    end
+
+    def default_database_configs
+      <<-YAML
+        default: &default
+          adapter: sqlite3
+          pool: 5
+          timeout: 5000
+        development:
+          <<: *default
+          database: db/development.sqlite3
+        test:
+          <<: *default
+          database: db/test.sqlite3
+        production:
+          <<: *default
+          database: db/production.sqlite3
+      YAML
+    end
+
+    def multi_db_database_configs
+      <<-YAML
         default: &default
           adapter: sqlite3
           pool: 5
@@ -185,40 +225,6 @@ module TestHelpers
             replica: true
       YAML
     end
-      else
-        File.open("#{app_path}/config/database.yml", "w") do |f|
-          f.puts <<-YAML
-          default: &default
-            adapter: sqlite3
-            pool: 5
-            timeout: 5000
-          development:
-            <<: *default
-            database: db/development.sqlite3
-          test:
-            <<: *default
-            database: db/test.sqlite3
-          production:
-            <<: *default
-            database: db/production.sqlite3
-          YAML
-        end
-      end
-
-      add_to_config <<-RUBY
-        config.hosts << proc { true }
-        config.eager_load = false
-        config.session_store :cookie_store, key: "_myapp_session"
-        config.cache_store = :mem_cache_store
-        config.active_support.deprecation = :log
-        config.action_controller.allow_forgery_protection = false
-      RUBY
-    end
-
-    def teardown_app
-      ENV["RAILS_ENV"] = @prev_rails_env if @prev_rails_env
-      FileUtils.rm_rf(tmp_path)
-    end
 
     # Make a very basic app, without creating the whole directory structure.
     # This is faster and simpler than the method above.