remove default empty value in drop_down_list

app/models/type_de_champ.rb

@@ -496,10 +496,8 @@ class TypeDeChamp < ApplicationRecord
     end
   end
 
-  DEFAULT_EMPTY = ['']
   def drop_down_list_value=(value)
-    split = value.to_s.lines.map(&:strip).reject(&:empty?)
-    self.drop_down_options = split.blank? ? [] : DEFAULT_EMPTY + split
+    self.drop_down_options = value.to_s.lines.map(&:strip).reject(&:empty?)
   end
 
   def header_section_level_value

app/models/types_de_champ/linked_drop_down_list_type_de_champ.rb

@@ -89,8 +89,10 @@ class TypesDeChamp::LinkedDropDownListTypeDeChamp < TypesDeChamp::TypeDeChampBas
   end
 
   def unpack_options
-    _, *options = drop_down_options
-    chunked = options.slice_before(PRIMARY_PATTERN)
+    chunked = drop_down_options
+      .reject(&:empty?) # TODO: remove after removing empty options
+      .slice_before(PRIMARY_PATTERN)
+
     chunked.map do |chunk|
       primary, *secondary = chunk
       secondary = add_blank_option_when_not_mandatory(secondary)
@@ -99,7 +101,8 @@ class TypesDeChamp::LinkedDropDownListTypeDeChamp < TypesDeChamp::TypeDeChampBas
   end
 
   def check_presence_of_primary_options
-    if !PRIMARY_PATTERN.match?(drop_down_options.second)
+    # TODO: replace by `drop_down_options.first` when the empty options are removed
+    if !PRIMARY_PATTERN.match?(drop_down_options.find(&:present?))
       errors.add(libelle.presence || "La liste", "doit commencer par une entrée de menu primaire de la forme <code style='white-space: pre-wrap;'>--texte--</code>")
     end
   end

spec/factories/type_de_champ.rb

@@ -96,7 +96,7 @@ FactoryBot.define do
     end
     factory :type_de_champ_linked_drop_down_list do
       type_champ { TypeDeChamp.type_champs.fetch(:linked_drop_down_list) }
-      drop_down_list_value { "--primary--\nsecondary\n" }
+      drop_down_list_value { "--primary--\r\nsecondary\n" }
     end
     factory :type_de_champ_expression_reguliere do
       type_champ { TypeDeChamp.type_champs.fetch(:expression_reguliere) }

spec/models/champs/linked_drop_down_list_champ_spec.rb

@@ -78,7 +78,7 @@ describe Champs::LinkedDropDownListChamp do
   end
 
   describe '#mandatory_and_blank' do
-    let(:value) { "--Primary--\nSecondary" }
+    let(:value) { "--Primary--\r\nSecondary" }
 
     subject { described_class.new }
     before { allow(subject).to receive(:type_de_champ).and_return(type_de_champ) }

spec/models/type_de_champ_spec.rb

@@ -203,7 +203,7 @@ describe TypeDeChamp do
       expect(type_de_champ.drop_down_options).to eq([])
 
       type_de_champ.drop_down_list_value = " 1 / 2 \r\n 3"
-      expect(type_de_champ.drop_down_options).to eq(['', '1 / 2', '3'])
+      expect(type_de_champ.drop_down_options).to eq(['1 / 2', '3'])
     end
   end
 

spec/system/administrateurs/types_de_champ_spec.rb

@@ -162,7 +162,7 @@ describe 'As an administrateur I can edit types de champ', js: true do
     fill_in 'Options de la liste', with: 'Un menu', fill_options: { clear: :backspace }
     check "Proposer une option « autre » avec un texte libre"
 
-    wait_until { procedure.active_revision.types_de_champ_public.first.drop_down_options == ['', 'Un menu'] }
+    wait_until { procedure.active_revision.types_de_champ_public.first.drop_down_options == ['Un menu'] }
     wait_until { procedure.active_revision.types_de_champ_public.first.drop_down_other == "1" }
     expect(page).to have_content('Formulaire enregistré')