Add System test example

Author: skryukov

spec/system/inertia_examples_spec.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe "InertiaExample", type: :system do
+  it "renders the text and increments the counter" do
+    visit inertia_example_path(name: "TestUser")
+
+    expect(page).to have_content("Hello TestUser!")
+    expect(page).to have_content("count is 0")
+
+    find("button", text: "count is 0").click
+
+    expect(page).to have_content("count is 1")
+  end
+end