From https://once.com/writebook

test/models/book_test.rb

@@ -0,0 +1,16 @@
+require "test_helper"
+
+class BookTest < ActiveSupport::TestCase
+  test "slug is generated from title" do
+    book = Book.create!(title: "Hello, World!")
+    assert_equal "hello-world", book.slug
+  end
+
+  test "press a leafable" do
+    leaf = books(:manual).press Page.new(body: "Important words"), title: "Introduction"
+
+    assert leaf.page?
+    assert_equal "Important words", leaf.page.body.content.to_s
+    assert_equal "Introduction", leaf.title
+  end
+end