add file_extension validation for file_type

app/models/file_type.rb

@@ -26,6 +26,7 @@ class FileType < ApplicationRecord
   validates :indent_size, presence: true, unless: :binary?
   validates :name, presence: true
   validates :renderable, inclusion: [true, false]
+  validates :file_extension, length: { minimum:0, allow_nil: false}
 
   %i[audio compressed csv excel image pdf powerpoint video word].each do |type|
     define_method("#{type}?") do

spec/factories/file_type.rb

@@ -186,6 +186,7 @@ FactoryBot.define do
   factory :makefile, class: 'FileType' do
     created_by_admin
     editor_mode { 'ace/mode/makefile' }
+    file_extension { '' }
     executable
     indent_size { 2 }
     name { 'Makefile' }

spec/models/file_type_spec.rb

@@ -54,4 +54,10 @@ describe FileType do
   it 'validates the presence of a user' do
     expect(file_type.errors[:user]).to be_present
   end
+
+  it 'validates the presence of the file_extension' do
+    expect(file_type.errors[:file_extension]).to be_present
+    file_type.update(file_extension: '')
+    expect(file_type.errors[:file_extension]).to be_blank
+  end
 end