Implement method that returns environment's folder

`Environment#folder_name` method returns a folder name that holds the
environment. If it is a top-level environment it will return environment
name, folder name otherwise.

app/models/environment.rb

@@ -82,12 +82,7 @@ class Environment < ActiveRecord::Base
   def set_environment_type
     names = name.split('/')
 
-    self.environment_type =
-      if names.many?
-        names.first
-      else
-        nil
-      end
+    self.environment_type = names.many? ? names.first : nil
   end
 
   def includes_commit?(commit)
@@ -101,7 +96,7 @@ class Environment < ActiveRecord::Base
   end
 
   def update_merge_request_metrics?
-    (environment_type || name) == "production"
+    folder_name == "production"
   end
 
   def first_deployment_for(commit)
@@ -223,6 +218,10 @@ class Environment < ActiveRecord::Base
       format: :json)
   end
 
+  def folder_name
+    self.environment_type || self.name
+  end
+
   private
 
   # Slugifying a name may remove the uniqueness guarantee afforded by it being

app/serializers/environment_entity.rb

@@ -27,7 +27,7 @@ class EnvironmentEntity < Grape::Entity
   end
 
   expose :folder_path do |environment|
-    folder_project_environments_path(environment.project, environment.environment_type || environment.name)
+    folder_project_environments_path(environment.project, environment.folder_name)
   end
 
   expose :created_at, :updated_at

app/serializers/environment_serializer.rb

@@ -36,9 +36,9 @@ class EnvironmentSerializer < BaseSerializer
   private
 
   def itemize(resource)
-    items = resource.order('folder_name ASC')
+    items = resource.order('folder ASC')
       .group('COALESCE(environment_type, name)')
-      .select('COALESCE(environment_type, name) AS folder_name',
+      .select('COALESCE(environment_type, name) AS folder',
               'COUNT(*) AS size', 'MAX(id) AS last_id')
 
     # It makes a difference when you call `paginate` method, because
@@ -49,7 +49,7 @@ class EnvironmentSerializer < BaseSerializer
     environments = resource.where(id: items.map(&:last_id)).index_by(&:id)
 
     items.map do |item|
-      Item.new(item.folder_name, item.size, environments[item.last_id])
+      Item.new(item.folder, item.size, environments[item.last_id])
     end
   end
 end

spec/models/environment_spec.rb

@@ -54,6 +54,28 @@ describe Environment do
     end
   end
 
+  describe '#folder_name' do
+    context 'when it is inside a folder' do
+      subject(:environment) do
+        create(:environment, name: 'staging/review-1')
+      end
+
+      it 'returns a top-level folder name' do
+        expect(environment.folder_name).to eq 'staging'
+      end
+    end
+
+    context 'when the environment if a top-level item itself' do
+      subject(:environment) do
+        create(:environment, name: 'production')
+      end
+
+      it 'returns an environment name' do
+        expect(environment.folder_name).to eq 'production'
+      end
+    end
+  end
+
   describe '#nullify_external_url' do
     it 'replaces a blank url with nil' do
       env = build(:environment, external_url: "")