Avoid generating invalid root route when there's no model

lib/generators/administrate/routes/routes_generator.rb

@@ -63,7 +63,8 @@ def unnamed_constants
       end
 
       def dashboard_routes
-        ERB.new(File.read(routes_file_path)).result(binding)
+        erb = ERB.new(File.read(routes_file_path), nil, "-")
+        erb.result(binding)
       end
 
       def rails_routes_file_path

lib/generators/administrate/routes/templates/routes.rb.erb

@@ -1,5 +1,7 @@
 namespace :admin do
-    <% dashboard_resources.each do |resource| %>resources :<%= resource %>
-<% end %>
+<% dashboard_resources.each do |resource| %>    resources :<%= resource %>
+<% end -%>
+<% unless dashboard_resources.empty? -%>
     root to: "<%= dashboard_resources.first %>#index"
+<% end -%>
   end

spec/generators/routes_generator_spec.rb

@@ -64,4 +64,14 @@ def self.table_name
 
     expect(routes).to contain('root to: "customers#index')
   end
+
+  it "does not create a invalid root route when there's no model" do
+    allow(ActiveRecord::Base).to receive(:descendants).and_return([])
+    stub_generator_dependencies
+    routes = file("config/routes.rb")
+
+    run_generator
+
+    expect(routes).not_to contain('root to: "#index"')
+  end
 end