fix(dossier.export): should not use default value when types_de_champ changed to a similar one

app/models/type_de_champ.rb

@@ -744,11 +744,27 @@ class TypeDeChamp < ApplicationRecord
       # no champ
       return true if champ.nil?
       # type de champ on the revision changed
-      return true if type_champ_to_champ_class_name(type_champ) != champ.type
+      if type_champ != champ.type_champ
+        return !castable_on_change?(type_champ, champ.type_champ)
+      end
       # special case for linked drop down champ – it's blank implementation is not what you think
       return champ.value.blank? if type_champ == TypeDeChamp.type_champs.fetch(:linked_drop_down_list)
       champ.blank?
     end
+
+    def castable_on_change?(from_type, to_type)
+      case [from_type, to_type]
+      when ['integer_number', 'decimal_number'], # recast numbers automatically
+        ['decimal_number', 'integer_number'], # may lose some data, but who cares ?
+        ['text', 'textarea'], # allow short text to long text
+        ['drop_down_list', 'multiple_drop_down_list'], # single list can become multi
+        ['date', 'datetime'], # date <=> datetime
+        ['datetime', 'date'] # may lose some data, but who cares ?
+        true
+      else
+        false
+      end
+    end
   end
 
   private

spec/models/champ_spec.rb

@@ -241,7 +241,10 @@ describe Champ do
       let(:value) { :noop }
       let(:champ_yes_no) { Champs::YesNoChamp.new(value: 'true') }
       let(:champ_text) { Champs::TextChamp.new(value: 'hello') }
-
+      before do
+        allow(champ_yes_no).to receive(:type_de_champ).and_return(build(:type_de_champ_yes_no))
+        allow(champ_text).to receive(:type_de_champ).and_return(build(:type_de_champ_text))
+      end
       it { expect(TypeDeChamp.champ_value_for_export('text', champ_yes_no)).to eq(nil) }
       it { expect(TypeDeChamp.champ_value_for_export('yes_no', champ_text)).to eq('Non') }
     end

spec/models/dossier_spec.rb

@@ -1996,18 +1996,17 @@ describe Dossier, type: :model do
 
   describe "champs_for_export" do
     context 'with integer_number' do
-      let(:procedure) { create(:procedure, types_de_champ_public: [{ type: :integer_number, libelle: 'c1' }]) }
+      let(:procedure) { create(:procedure, :published, types_de_champ_public: [{ type: :integer_number, libelle: 'c1' }]) }
       let(:dossier) { create(:dossier, :with_populated_champs, procedure:) }
       let(:integer_number_type_de_champ) { procedure.active_revision.types_de_champ_public.find { |type_de_champ| type_de_champ.type_champ == TypeDeChamp.type_champs.fetch(:integer_number) } }
 
       it 'give me back my decimal number' do
-        procedure.publish!
         dossier
-        integer_number_type_de_champ.update(type_champ: :decimal_number)
-        procedure.update(published_revision: procedure.draft_revision, draft_revision: procedure.create_new_revision)
-        dossier.reload
-
-        expect(dossier.champs_for_export(procedure.types_de_champ_for_procedure_presentation.not_repetition.to_a)).to eq([['c1', 42]])
+        expect {
+          integer_number_type_de_champ.update(type_champ: :decimal_number)
+          procedure.update(published_revision: procedure.draft_revision, draft_revision: procedure.create_new_revision)
+        }.to change { dossier.reload.champs_for_export(procedure.types_de_champ_for_procedure_presentation.not_repetition.to_a) }
+          .from([["c1", 42]]).to([["c1", 42.0]])
       end
     end
     context 'with a unconditionnal procedure' do