Add presence of problem to translation

app/controllers/translations_controller.rb

@@ -69,6 +69,6 @@ class TranslationsController < ApplicationController
 
     # Never trust parameters from the scary internet, only allow the white list through.
     def translation_params
-      params.require(:translation).permit(:title, :content)
+      params.require(:translation).permit(:title, :content, :problem_id)
     end
 end

app/models/translation.rb

@@ -1,7 +1,7 @@
 class Translation < ActiveRecord::Base
   belongs_to :problem, inverse_of: :translations
 
-  validates :title, :content, presence: true
+  validates :title, :content, :problem, presence: true
   validates :title, uniqueness: true
 
   self.per_page = 50

test/controllers/translations_controller_test.rb

@@ -5,7 +5,8 @@ class TranslationsControllerTest < ActionController::TestCase
     @translation = translations(:one)
     @update = {
         title: 'New title',
-        content: 'This is the new content'
+        content: 'This is the new content',
+        problem_id: Problem.first
     }
   end
 

test/fixtures/translations.yml

@@ -1,9 +1,11 @@
 # Read about fixtures at http://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
 
 one:
+  problem: one
   title: First title
   content: The content of the translation
 
 two:
+  problem: two
   title: Second title
   content: The content of the second translation

test/models/translation_test.rb

@@ -22,7 +22,8 @@ class TranslationTest < ActiveSupport::TestCase
   test "should save correct translation" do
     translation = Translation.new(
         title: 'A unique title',
-        content: 'Some content'
+        content: 'Some content',
+        problem: Problem.first
     )
     assert translation.save
   end