ror_id should be unique.

add some tests

app/models/institution.rb

@@ -6,6 +6,7 @@ class Institution < ApplicationRecord
   auto_strip_attributes :web_page
 
   validates :title, uniqueness: true
+  validates :ror_id, uniqueness: true, allow_blank: true
   validates :web_page, url: { allow_nil: true, allow_blank: true }
   validates :country, country: true
 

test/functional/institutions_controller_test.rb

@@ -50,6 +50,22 @@ def test_can_not_create_institution_with_invalid_ror_id
       assert_equal assigns(:institution).errors[:ror_id].first, 'is invalid.'
   end
 
+
+  def test_can_not_create_institution_with_the_title_or_ror_id_that_already_exists
+    FactoryBot.create(:institution, title: 'my Institution', ror_id:'01f7bcy98')
+
+    assert_no_difference('Institution.count') do
+      post :create, params: { institution: { title: 'my Institution'} }
+    end
+    assert_equal assigns(:institution).errors[:title].first, 'has already been taken'
+
+    assert_no_difference('Institution.count') do
+      post :create, params: { institution: { title: 'my Institution new', ror_id:'01f7bcy98'} }
+    end
+    assert_equal assigns(:institution).errors[:ror_id].first, 'has already been taken'
+
+  end
+
   def test_should_show_institution
     get :show, params: { id: institutions(:one).id }
     assert_response :success

test/unit/institution_test.rb

@@ -114,11 +114,19 @@ def test_can_be_edited_by
     i.ror_id='01f7bcy98'
     assert i.valid?
 
+    i.ror_id = ''
+    assert i.valid?
+
     i.ror_id = '1121'
     assert !i.valid?
 
     i.ror_id = '1121-1121-1121'
     assert !i.valid?
+
+    #duplicate ror_id
+    existing_institution = FactoryBot.create(:institution, ror_id: '01f7bcy98')
+    new_institution = FactoryBot.build(:institution, ror_id: existing_institution.ror_id)
+    assert_not new_institution.valid?
   end
 
   test 'test uuid generated' do