Change domains.delete_at database column type to date, rename to

`delete_date`

Closes #1125

test/tasks/data_migrations/convert_domain_delete_date_test.rb

@@ -0,0 +1,61 @@
+require 'test_helper'
+
+class ConvertDomainDeleteDateTaskTest < ActiveSupport::TestCase
+  setup do
+    @domain = domains(:shop)
+  end
+
+  def test_moves_domain_delete_date_one_day_ahead
+    @domain.update!(delete_date: '2010-07-05')
+
+    capture_io do
+      run_task
+    end
+    @domain.reload
+
+    assert_equal Date.parse('2010-07-06'), @domain.delete_date
+  end
+
+  def test_processes_invalid_domains
+    @domain = domains(:invalid)
+    @domain.update_columns(delete_date: '2010-07-05')
+
+    capture_io do
+      run_task
+    end
+    @domain.reload
+
+    assert_equal Date.parse('2010-07-06'), @domain.delete_date
+  end
+
+  def test_skips_non_expired_domains
+    @domain.update!(delete_date: nil)
+
+    assert_nothing_raised do
+      capture_io do
+        run_task
+      end
+    end
+  end
+
+  def test_output
+    eliminate_effect_of_all_domains_except(@domain)
+    @domain.update!(delete_date: '2010-07-05')
+
+    assert_output "Domains processed: 1\n" do
+      run_task
+    end
+  end
+
+  private
+
+  def eliminate_effect_of_all_domains_except(domain)
+    Domain.connection.disable_referential_integrity do
+      Domain.delete_all("id != #{domain.id}")
+    end
+  end
+
+  def run_task
+    Rake::Task['data_migrations:convert_domain_delete_date'].execute
+  end
+end