Champ: add before save logic to serialize datetime and dropdownlist fields

spec/models/champ_spec.rb

@@ -4,4 +4,63 @@ describe Champ do
   require 'models/champ_shared_example.rb'
 
   it_should_behave_like "champ_spec"
+
+  describe '#serialize_datetime_if_needed' do
+    let(:type_de_champ) { TypeDeChamp.new(type_champ: 'datetime') }
+    let(:champ) { Champ.new(type_de_champ: type_de_champ, value: value) }
+
+    before { champ.save }
+
+    # when using the old form, and the ChampsService Class
+    # TODO: to remove
+    context 'when the value is already serialized' do
+      let(:value) { '12/01/2017 10:23' }
+
+      it { expect(champ.value).to eq(value) }
+    end
+
+    context 'when the value is not already serialized' do
+      let(:value) { '{ 1=>2017, 2=>01, 3=>12, 4=>10, 5=>23  }' }
+
+      it { expect(champ.value).to eq('12/01/2017 10:23') }
+    end
+  end
+
+  describe '#multiple_select_to_string' do
+    let(:type_de_champ) { TypeDeChamp.new(type_champ: 'multiple_drop_down_list') }
+    let(:champ) { Champ.new(type_de_champ: type_de_champ, value: value) }
+
+    before { champ.save }
+
+    # when using the old form, and the ChampsService Class
+    # TODO: to remove
+    context 'when the value is already deserialized' do
+      let(:value) { '["1", "2"]' }
+
+      it { expect(champ.value).to eq(value) }
+
+      context 'when the value is nil' do
+        let(:value) { nil }
+
+        it { expect(champ.value).to eq(value) }
+      end
+    end
+
+    # for explanation for the "" entry, see
+    # https://apidock.com/rails/ActionView/Helpers/FormOptionsHelper/select
+    # GOTCHA
+    context 'when the value is not already deserialized' do
+      context 'when a choice is selected' do
+        let(:value) { '["", "1", "2"]' }
+
+        it { expect(champ.value).to eq('["1", "2"]') }
+      end
+
+      context 'when all choices are removed' do
+        let(:value) { '[""]' }
+
+        it { expect(champ.value).to eq(nil) }
+      end
+    end
+  end
 end