filter out locale from stored query params

As 'locale' isn't a param we want to prefill a dossier, we ignore it
and remove it from the stored query params.

app/controllers/concerns/query_params_store_concern.rb

@@ -8,9 +8,9 @@ module QueryParamsStoreConcern
   def store_query_params
     # Don't override already stored params, because we could do goings and comings with authentication, and
     # lost previously stored params
-    return if stored_query_params? || request.query_parameters.empty?
+    return if stored_query_params? || filtered_query_params.empty?
 
-    session[:stored_params] = request.query_parameters.to_json
+    session[:stored_params] = filtered_query_params.to_json
   end
 
   def retrieve_and_delete_stored_query_params
@@ -22,4 +22,10 @@ module QueryParamsStoreConcern
   def stored_query_params?
     session[:stored_params].present?
   end
+
+  private
+
+  def filtered_query_params
+    request.query_parameters.except(:locale, "locale")
+  end
 end

spec/controllers/concerns/query_params_store_concern_spec.rb

@@ -36,6 +36,14 @@ RSpec.describe QueryParamsStoreConcern, type: :controller do
         expect { store_query_params }.to change { session[:stored_params] }.from(nil).to(params.to_json)
       end
     end
+
+    context 'when params contain a locale' do
+      let(:params) { { locale: "fr", param2: "param2" } }
+
+      it "does not store the locale" do
+        expect { store_query_params }.to change { session[:stored_params] }.from(nil).to({ param2: "param2" }.to_json)
+      end
+    end
   end
 
   describe '#retrieve_and_delete_stored_query_params' do