Document collection search options alerts the user

If no radio button is selected, then set an alert

app/controllers/admin/document_collection_group_document_search_controller.rb

@@ -7,6 +7,10 @@ class Admin::DocumentCollectionGroupDocumentSearchController < Admin::BaseContro
   def search_options; end
 
   def search
+    unless params[:search_option].present?
+      flash.now[:alert] = "Please select a search option"
+      render :search_options
+    end
     redirect_to(action: :search_title_slug, document_collection_id: @collection, group_id: @group) if params[:search_option] == "title-or-slug"
   end
 

test/functional/admin/document_collection_group_document_search_controller_test.rb

@@ -15,6 +15,19 @@ class Admin::DocumentCollectionGroupDocumentSearchControllerTest < ActionControl
     assert_template "document_collection_group_document_search/search_options"
   end
 
+  view_test "POST #search with an empty option shows an alert flash" do
+    @request_params[:search_option] = ""
+    post :search, params: @request_params
+    assert_template "document_collection_group_document_search/search_options"
+    assert_select ".gem-c-error-alert__message", text: /Please select a search option/
+  end
+
+  view_test "POST #search with no search options shows an alert flash" do
+    post :search, params: @request_params
+    assert_template "document_collection_group_document_search/search_options"
+    assert_select ".gem-c-error-alert__message", text: /Please select a search option/
+  end
+
   test "POST #search is a noop when passed param is unrecognised" do
     @request_params[:search_option] = "non-existant"
     post :search, params: @request_params