Try to add specs

spec/integration/cli/server_spec.rb

@@ -364,4 +364,17 @@ def listing
       end
     end
   end
+
+  context "without email" do
+    it "returns page" do
+      with_project do
+        replace "config/environment.rb", "delivery :test", ""
+
+        server do
+          visit "/"
+          expect(page).to have_title("Hanami | The web, with simplicity")
+        end
+      end
+    end
+  end
 end

spec/isolation/components/mailer_configuration/without_hanami_mailer_spec.rb

@@ -0,0 +1,15 @@
+RSpec.describe "Components: mailer.configuration", type: :cli do
+  context "without hanami-mailer" do
+    it "resolves mailer configuration" do
+      with_project do
+        environment_file = Pathname.new(Dir.pwd).join("config", "environment")
+        peplace "#{environment_file}.rb", "delivery :test", ""
+
+        require environment_file
+        Hanami::Components.resolve('mailer.configuration')
+
+        expect(Hanami::Components['mailer.configuration']).to be nil
+      end
+    end
+  end
+end