From https://once.com/writebook

test/test_helpers/session_test_helper.rb

@@ -0,0 +1,16 @@
+module SessionTestHelper
+  def parsed_cookies
+    ActionDispatch::Cookies::CookieJar.build(request, cookies.to_hash)
+  end
+
+  def sign_in(user)
+    user = users(user) unless user.is_a? User
+    post session_url, params: { email_address: user.email_address, password: "secret123456" }
+    assert cookies[:session_token].present?
+  end
+
+  def sign_out
+    delete session_url
+    assert_not cookies[:session_token].present?
+  end
+end

test/test_helpers/system_test_helper.rb

@@ -0,0 +1,20 @@
+module SystemTestHelper
+  include ActionView::Helpers::JavaScriptHelper
+
+  def sign_in(email_address, password = "secret123456")
+    visit new_session_url
+
+    fill_in "email_address", with: email_address
+    fill_in "password", with: password
+
+    click_on "log_in"
+    assert_selector "h2", text: "Handbook"
+  end
+
+  def fill_house_editor(name, content)
+    execute_script <<~JS
+      const editor = document.querySelector("[name='#{name}']")
+      editor.value = "#{escape_javascript(content)}"
+    JS
+  end
+end