form: add number to section headers

app/models/champs/header_section_champ.rb

@@ -2,4 +2,11 @@ class Champs::HeaderSectionChamp < Champ
   def search_terms
     # The user cannot enter any information here so it doesn’t make much sense to search
   end
+
+  def section_index
+    dossier
+      .champs
+      .filter { |c| c.type_champ == TypeDeChamp.type_champs.fetch(:header_section) }
+      .index(self) + 1
+  end
 end

app/views/shared/dossiers/editable_champs/_header_section.html.haml

@@ -1,2 +1,6 @@
+- section_index = champ.section_index
+
 %h2.header-section
+  - if section_index
+    = "#{section_index}."
   = champ.libelle

spec/models/champs/header_section_champ_spec.rb

@@ -0,0 +1,26 @@
+require 'spec_helper'
+
+describe Champs::CheckboxChamp do
+  let(:types_de_champ) do
+    [
+      create(:type_de_champ_header_section),
+      create(:type_de_champ_civilite),
+      create(:type_de_champ_text),
+      create(:type_de_champ_header_section),
+      create(:type_de_champ_email)
+    ]
+  end
+
+  let(:procedure) { create(:procedure, types_de_champ: types_de_champ) }
+  let(:dossier) { create(:dossier, procedure: procedure) }
+
+  describe '#section_index' do
+    let(:first_header)  { dossier.champs[0] }
+    let(:second_header) { dossier.champs[3] }
+
+    it 'returns the index of the section (starting from 1)' do
+      expect(first_header.section_index).to eq 1
+      expect(second_header.section_index).to eq 2
+    end
+  end
+end