From https://once.com/writebook

test/controllers/sections_controller_test.rb

@@ -0,0 +1,37 @@
+require "test_helper"
+
+class SectionsControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    sign_in :kevin
+  end
+
+  test "create" do
+    post book_sections_path(books(:handbook), format: :turbo_stream)
+    assert_response :success
+
+    new_section = Section.last
+    assert_equal "Section", new_section.title
+    assert_equal books(:handbook), new_section.leaf.book
+  end
+
+  test "update" do
+    put leafable_path(leaves(:welcome_section)), params: {
+      leaf: { title: "Title" },
+      section: { body: "Section body" }
+    }
+    assert_response :success
+
+    section = leaves(:welcome_section).reload.leafable
+    assert_equal "Title", section.title
+    assert_equal "Section body", section.body
+  end
+
+  test "update with no body supplied" do
+    put leafable_path(leaves(:welcome_section)), params: { leaf: { title: "New title" } }
+    assert_response :success
+
+    section = leaves(:welcome_section).reload.leafable
+    assert_equal "New title", section.title
+    assert_equal "New title", section.body
+  end
+end