add spec for count dossiers termines by month

spec/models/traitement_spec.rb

@@ -0,0 +1,37 @@
+describe Traitement do
+  describe '#count_dossiers_termines_by_month' do
+    let(:procedure) { create(:procedure, :published, groupe_instructeurs: [groupe_instructeurs]) }
+    let(:groupe_instructeurs) { create(:groupe_instructeur) }
+    let(:result) { Traitement.count_dossiers_termines_by_month(groupe_instructeurs) }
+
+    before do
+      create_dossier_for_month(procedure, 2021, 3)
+      create_dossier_for_month(procedure, 2021, 3)
+      create_dossier_for_month(procedure, 2021, 2)
+      Timecop.freeze(Time.zone.local(2021, 3, 5))
+    end
+
+    it 'count dossiers_termines by month' do
+      expect(count_for_month(result, 3)).to eq 2
+      expect(count_for_month(result, 2)).to eq 1
+    end
+
+    it 'returns descending order by month' do
+      expect(result[0]["month"].to_date.month).to eq 3
+      expect(result[1]["month"].to_date.month).to eq 2
+    end
+  end
+
+  private
+
+  def count_for_month(count_dossiers_termines_by_month, month)
+    count_dossiers_termines_by_month.find do |count_by_month|
+      count_by_month["month"].to_date.month == month
+    end["count"]
+  end
+
+  def create_dossier_for_month(procedure, year, month)
+    Timecop.freeze(Time.zone.local(year, month, 5))
+    create(:dossier, :accepte, :with_attestation, procedure: procedure)
+  end
+end